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Shoulder Instability: A Comprehensive Approach E-Book

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1088 pages
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Description

Shoulder Instability, by Drs. Mark Provencher and Anthony Romeo, is the first comprehensive resource that helps you apply emerging research to effectively manage this condition using today’s best surgical and non-surgical approaches. Detailed illustrations and surgical and rehabilitation videos clearly demonstrate key techniques like bone loss treatment, non-operative rehabilitation methods, multidirectional instability, and more. You’ll also have access to the full contents online at www.expertconsult.com.

  • Watch surgical and rehabilitation videos online and access the fully searchable text at www.expertconsult.com.
  • Stay current on hot topics including instability with bone loss treatment, non-operative rehabilitation methods, multidirectional instability, and more.
  • Gain a clear visual understanding of the treatment of shoulder instability from more than 850 images and illustrations.
  • Find information quickly and easily with a consistent format that features pearls and pitfalls, bulleted key points, and color-coded side tabs.
  • Explore shoulder instability further with annotated suggested readings that include level of evidence.

State-of-the-art, comprehensive resource for the surgical and non-surgical treatment of shoulder instability


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Publié par
Date de parution 11 octobre 2011
Nombre de lectures 0
EAN13 9781455728213
Langue English
Poids de l'ouvrage 17 Mo

Informations légales : prix de location à la page 0,0894€. Cette information est donnée uniquement à titre indicatif conformément à la législation en vigueur.

Exrait

Shoulder Instability: A Comprehensive Approach

Matthew T. Provencher, MD, CDR, MC, USN
Associate Professor of Surgery, Orthopaedics, Uniformed Services University of the Health Sciences (USUHS) Bethesda, Maryland; Director, Orthopaedic Shoulder, Knee, and Sports Surgery, Department of Orthopaedic Surgery, Naval Medical Center San Diego, San Diego, California

Anthony A. Romeo, MD
Professor, Department of Orthopaedics, Rush University Medical Center; Head, Section of Shoulder and Elbow Surgery, Division of Sports Medicine, Chicago, Illinois
Saunders
Front matter

Shoulder instability
A Comprehensive Approach
Matthew T. Provencher, MD, CDR, MC, USN
Associate Professor of Surgery, OrthopaedicsUniformed Services University of the Health Sciences (USUHS)Bethesda, Maryland;
Director, Orthopaedic Shoulder, Knee, and Sports Surgery
Department of Orthopaedic Surgery
Naval Medical Center San Diego
San Diego, California
Anthony A. Romeo, MD
Associate Professor of Orthopaedics
Director, Section of Shoulder and Elbow Surgery
Department of Orthopaedic Surgery
Rush University Medical Center
Chicago, Illinois
Copyright

1600 John F. Kennedy Blvd.
Ste 1800
Philadelphia, PA 19103-2899
Shoulder Instability: A Comprehensive Approach ISBN: 978-1-4377-0922-3
Copyright © 2012 by Saunders, an imprint of Elsevier Inc.
No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Details on how to seek permission, further information about the Publisher’s permissions policies and our arrangements with organizations such as the Copyright Clearance Center and the Copyright Licensing Agency, can be found at our website: www.elsevier.com/permissions .
This book and the individual contributions contained in it are protected under copyright by the Publisher (other than as may be noted herein).


Notices
Knowledge and best practice in this field are constantly changing. As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary.
Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein. In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility.
With respect to any drug or pharmaceutical products identified, readers are advised to check the most current information provided (i) on procedures featured or (ii) by the manufacturer of each product to be administered, to verify the recommended dose or formula, the method and duration of administration, and contraindications. It is the responsibility of practitioners, relying on their own experience and knowledge of their patients, to make diagnoses, to determine dosages and the best treatment for each individual patient, and to take all appropriate safety precautions.
To the fullest extent of the law, neither the Publisher nor the authors, contributors, or editors, assume any liability for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein.
Library of Congress Cataloging-in-Publication Data
Shoulder instability : a comprehensive approach / [edited by] Matthew T.
Provencher, Anthony A. Romeo. -- 1st ed.
p. ; cm.
Includes bibliographical references and index.
ISBN 978-1-4377-0922-3 (hardcover : alk. paper)
I. Provencher, Matthew T. II. Romeo, Anthony A.
[DNLM: 1. Joint Instability--therapy. 2. Shoulder Joint--physiopathology. 3. Joint Instability--diagnosis. 4. Shoulder--physiopathology. WE 810]
LC classification not assigned
617.5"7059--dc23
2011031536
Acquisitions Editor: Daniel Pepper
Developmental Editor: Virginia Wilson
Editorial Assistant: Lee Hood
Publishing Services Manager: Jeff Patterson
Project Manager: Bill Drone
Designer: Ellen Zanolle
Printed in China
Last digit is the print number: 9 8 7 6 5 4 3 2 1
Dedication
This book is dedicated to my family, including my wife, Melissa, and four children, Connor, Brody, Caroline, and Catherine, as well as my loving and supportive parents who taught me the value of hard work and perseverance.

Matthew T. Provencher, MD, CDR, MC, USN
This book is dedicated to Brianna, Alyssa, Danielle, Christin, and Sabrina, as well as my parents, for their love and support.

Anthony A. Romeo, MD
Contributors

Robert A. Arciero, MD, Clinical Professor, University of Connecticut, Farmington, Connecticut

COL, Edward D. Arrington, MD, Program Director, Orthopedic Surgery, Madigan Army Medical Center, Joint Base Lewis-McChord, WA;, Assistant Professor of Surgery, Uniformed Services University of the Health Sciences, Bethesda, Maryland

F. Alan Barber, MD, FACS, Sutures and Glenoid Anchors for Instability, Fellowship Director, Plano Orthopedic, Sports Medicine, and Spine Center, Plano, Texas

Joseph U. Barker, MD, Orthopaedic Surgeon, Raleigh Orthopaedic Clinic, Raleigh, North Carolina

Paolo Baudi, MD, Rush University, Department of Orthopaedic Surgery, Chicago, Illinois;, Resident, Orthopaedic Department - Modena, Ramazzini Hospital, Carpi (Modena), Italy

Eric D. Bava, MD, Fellow, W.B. Carrell Memorial Clinic, Dallas, Texas

Violaine Beauthier, MD, Orthopaedic Surgeon, Orthopaedic Surgery Unit, Ambroise Pare Hospital, Boulogne-Billancourt, France

Andrew S. Bernhardson, MD, LT MC USN, 1 st Marine Logistics Group, 1 st Marine Expeditionary Force, Camp Pendleton, Oceanside, California

Sanjeev Bhatia, MD, Resident, Department of Orthopaedic Surgery, Rush University Medical Center, Chicago, Illinois

Pascal Boileau, MD, Chairman, Orthopaedic Surgery and Sports Traumatology, L’Archet 2 Hospital, University of Nice-Sophia-Antipolis, Nice, France

Ron Boucher, MD, Chairman, Radiology, Naval Medical Center San Diego, San Diego, California

James P. Bradley, MD, Head Team Physician, Pittsburgh Steelers, Clinical Professor, University of Pittsburgh Medical Center, Department of Orthopaedic Surgery, Pittsburgh, Pennsylvania

John J. Brems, MD, Shoulder Fellowship Director, Orthopaedic Surgery, Cleveland Clinic Foundation, Cleveland, Ohio

Wayne Z. Burkhead, Jr., MD, Clinical Professor of Orthopaedics, University of Texas Southwestern Medical School, The Carrell Clinic, Dallas, Texas

Travis C. Burns, MD, Fellow, John A. Feagin, Jr. Sports Medicine Fellowship, Keller Army Hospital, West Point, New York

Daniel D. Buss, MD, Orthopaedic Surgeon, Sports and Orthopaedic Specialists, Edina, Minnesota

Fabrizio Campi, MD, Surgeon, Unit of Shoulder and Elbow Surgery, “D. Cervesi” Hospital, Cattolica, Italy

Alberto Costantini, MD, Arthroscopic Surgery Department, Concordia Hospital for Special Surgery, Rome, Italy

Dana C. Covey, MD, MSc, FACS, Captain, Medical Corps, US Navy, Department of Orthopaedic Surgery, Naval Medical Center San Diego, Clinical Professor of Othopaedic Surgery, University of California San Diego, San Diego, California

Adnan Cutuk, MD, Sports Medicine Fellow, University of Michigan, MedSport - Department of Orthopaedic Surgery, Ann Arbor, Michigan

Leah T. Cyran, MD, Shoulder Fellow, The Carrell Clinic, Dallas, Texas

Tal S. David, MD, SportsMed Surgery Associates, Clinical Instructor, Department of Orthopedics, University of California, San Diego;, Director of Orthopedic Surgery, Surgical Center of San Diego, San Diego, California

Thomas M. DeBerardino, MD, Associate Professor, Department of Orthopaedic Surgery, New England Musculoskeletal Institute, University of Connecticut Health Science Center, Farmington, Connecticut

Nicola De Gasperis, MD, Arthroscopic Surgery Department, Concordia Hospital for Special Surgery, Rome, Italy

Andrea De Vita, MD, Arthroscopic Surgery Department, Concordia Hospital for Special Surgery, Rome, Italy

Christopher B. Dewing, MD, LCDR MC USN, Director of Sports and Shoulder Surgery, Department of Orthopaedic Surgery, Naval Medical Center San Diego, San Diego, California

Giovanni Di Giacomo, MD, Arthroscopic Surgery Department, Concordia Hospital for Special Surgery, Rome, Italy

Francesco Fauci, MD, Surgeon, Unit of Shoulder and Elbow Surgery, “D. Cervesi” Hospital, Cattolica, Italy

Rachel M. Frank, MD, Resident, Department of Orthopaedic Surgery, Rush University Medical Center, Chicago, Illinois

Juan Garzon-Muvdi, MD, Research Fellow, Division of Shoulder Surgery, Department of Orthopedic Surgery, The Johns Hopkins University, Baltimore, Maryland

Neil S. Ghodadra, MD, Attending Physician, Southern California Orthopedic Institute, Van Nuys, California

Michael C. Glanzmann, MD, Orthopedic Surgeon, Upper Extremity, Schulthessclinic Zürich, Zürich, Switzerland

R. Michael Greiwe, MD, Clinical Fellow, Center for Shoulder, Elbow, and Sports Medicine, Columbia University Medical Center, New York, New York

Lawrence V. Gulotta, MD, Fellow, Sports Medicine and Shoulder Service, Hospital for Special Surgery, New York, New York

Peter Habermeyer, MD, Professor, Department of Shoulder and Elbow Surgery, ATOS Clinic Heidelberg, Heidelberg, Germany

Philipe Hardy, MD, PhD, Professor, Orthopaedic Surgery Unit, Ambroise Pare Hospital, West Paris University, Boulogne-Billancourt, France

Scott A. Hrnack, MD, Action Orthopaedics and Sports Medicine, Director of Sports Medicine for Wise Regional Medical Center, Decatur, Texas

Kellie Huxel Bliven, PhD, ATC, Associate Professor, Interdisciplinary Health Sciences, A.T. Still University, Mesa, Arizona

Andreas B. Imhoff, MD, Professor of Orthopaedic Surgery and Traumatology, Director, Department of Orthopaedic Sports Medicine, Hospital Rechts der Isar, University of Munich, Munich, Germany

Eiji Itoi, MD, PhD, Professor and Chairman, Department of Orthopedic Surgery, Tohoku University School of Medicine, Sendai, Japan

Edward J. Kane, PT, PhD, ECS, SCS, ATC, Associate Professor, University of St. Augustine at San Diego, San Diego, California

W. Ben Kibler, MD, Medical Director, Shoulder Center of Kentucky, Lexington Clinic, Lexington, Kentucky

Seung-Ho Kim, MD, Director, Madi Hospital, Clinical Professor, Department of Orthopaedic Surgery, Sungkyunkwan University School of Medicine, Seoul, Korea

Erick J. Kozlowski, MS, ATC, PES, CES, Staff Athletic Trainer, Football and Wrestling, United States Air Force Academy, USAF Academy, Colorado

Sumant G. Krishnan, MD, Clinical Assistant Professor, University of Texas Southwestern Medical Center, Shoulder and Elbow Service, The Carrell Clinic, Dallas, Texas

Lance E. LeClere, MD, LT MC USN, Resident, Department of Orthopaedic Surgery, Naval Medical Center San Diego, San Diego, California

Thay Q. Lee, PhD, Senior Research Career Scientist - VA Long Beach Healthcare System, Professor and Vice Chairman for Research - Department of Orthopaedic Surgery, Professor - Department of Biomedical Engineering, University of California Irvine, Orthopaedic Biomechanics Laboratory, VA Long Beach Healthcare System (09/151), Long Beach, California

William N. Levine, MD, Vice Chairman and Professor, Department of Orthopaedic Surgery, Co-Director of the Center for Shoulder, Elbow, and Sports Medicine, New York Presbyterian Hospital, Columbia University Medical Center, New York, New York

Bernard K.H. Lin, MD, Shoulder, Sport Medicine, and Arthroscopy Fellow, Concordia Hospital for Special Surgery, Rome, Italy

Ian Lo, MD, FRCSC, Assistant Professor of Surgery, University of Calgary, Calgary, Alberta, Canada

Leonard C. Macrina, MSPT, SCS, CSCS, Physical Therapist, Champion Sports Medicine, American Sports Medicine Institute, Birmingham, Alabama

LTC Bryant G. Marchant, MD, Chief, Sports Medicine, Madigan Army Medical Center, Joint Base Lewis-McChord, Washington

Augustus D. Mazzocca, MS, MD, Associate Professor, Shoulder and Elbow Surgery, University of Connecticut Health Center, Department of Orthopaedic Surgery, Farmington, Connecticut

L. Pearce McCarty, III, MD, Shoulder and Elbow Surgery, Cartilage Restoration, Orthopaedic Sports Medicine, Sports and Orthopaedic Specialists, Minneapolis, Minnesota

Edward G. McFarland, MD, Wayne H. Lewis Chair of Orthopaedics and Shoulder Surgery, Co-Director, Division of Shoulder Surgery, Vice-Chairman, Department of Orthopaedic Surgery, The Johns Hopkins University, Baltimore, Maryland

Kevin C. McGill, MD, MPH, Department of General Surgery, William Beaumont Hospital, Royal Oak, Michigan

Paul Metzger, MD, LT MC USN, Resident, Department of Orthopaedic Surgery, Naval Medical Center San Diego, San Diego, California

Peter J. Millett, MD, MSc, Shoulder and Sports Medicine, The Steadman Clinic, Vail, Colorado

Michael J. O’Brien, MD, Assistant Professor of Orthopaedics, Tulane University Medical Center, New Orleans, Louisiana

Jason Old, MD, Assistant Professor, Section of Orthopaedic Surgery, University of Manitoba, Pan Am Clinic, Winnipeg, Manitoba, Canada

Kieran O’Shea, MB FRCS Orth, Department of Orthopaedic Surgery, St. James Hospital, Dublin, Ireland

Brett D. Owens, MD, Associate Professor, John A. Feagin, Jr. Sports Medicine Fellowship, Keller Army Hospital, West Point, New York

Michael J. Pagnani, MD, Director, Nashville Knee & Shoulder Center, Nashville, Tennessee

Paolo Paladini, MD, Unit of Shoulder and Elbow Surgery, “D. Cervesi” Hospital, Cattolica, Italy

CPT(P) Stephen A. Parada, MD, Chief Resident, Orthopaedic Surgery, Madigan Army Medical Center, Joint Base Lewis-McChord, Washington

Maxwell C. Park, MD, Partner Physician, Southern California Permanente Medical Group, Clinical Faculty, Orthopaedic Biomechanics Laboratory, VA Long Beach Healthcare System, University of California, Irvine, Department of Orthopaedic Surgery, Kaiser Foundation Hospital—Woodland Hills Medical Center, Los Angeles, California

Steve A. Petersen, MD, Associate Professor, Co-Director, Division of Shoulder Surgery, Department of Orthopaedic Surgery, The Johns Hopkins University, Baltimore, Maryland

Giuseppe Porcellini, MD, Orthopaedic Surgeon, Chief of Unit of Shoulder and Elbow Surgery, “D. Cervesi” Hospital, Cattolica, Italy

Matthew T. Provencher, MD, CDR, MC, USN, Associate Professor of Surgery, Orthopaedics, Uniformed Services University of the Health Sciences (USUHS), Bethesda, Maryland;, Director, Orthopaedic Shoulder, Knee, and Sports Surgery, Department of Orthopaedic Surgery, Naval Medical Center San Diego, San Diego, California

Brian Puskas, MD, Orthopaedic Surgery, Boston University, Boston Medical Center, Boston, Massachusetts

Michael M. Reinold, PT, DPT, SCS, ATC, CSCS, Head Athletic Trainer, Boston Red Sox, Boston, Massachusetts

Anthony A. Romeo, MD, Professor, Department of Orthopaedics, Rush University Medical Center, Head, Section of Shoulder and Elbow Surgery, Division of Sports Medicine, Chicago, Illinois

Michael D. Rosenthal, PT, DSc, SCS, ECS, ATC, CSCS, Director of Physical and Occupational Therapy, Naval Medical Center, San Diego, California

Sanjay Sanghavi, MS (Ortho), MBBS, Hospital Ambroise Pare, West Paris University, Boulogne, France

Hirotaka Sano, MD, PhD, Department of Orthopaedic Surgery, Tohoku University School of Medicine, Sendai, Miyagi Prefecture, Japan

Felix H. Savoie, MD, Lee C. Schlesinger Professor of Orthopaedic Surgery, Tulane University School of Medicine, Director, Tulane Institute of Sports Medicine, New Orleans, Louisiana

Anthony Schepsis, MD, Professor of Orthopedic Surgery, Director of Sports Medicine, Boston University Medical Center, Boston, Massachusetts

Aaron Sciascia, MS, ATC, NASM-PES, Coordinator, Shoulder Center of Kentucky, Lexington, Kentucky

Jon K. Sekiya, MD, Associate Professor, University of Michigan, MedSport - Department of Orthopaedic Surgery, Ann Arbor, Michigan

Anup A. Shah, MD, Harvard Medical School, Massachusetts General Hospital, Boston, Massachusetts

Alexander Y. Shin, MD, Professor and Consultant, Department of Orthopedic Surgery, Division of Hand Surgery, Mayo Clinic, Rochester, Minnesota

Daniel J. Solomon, MD, Partner, Marin Orthopedics and Sports Medicine, Novato, California

Jeffrey Spang, MD, Assistant Professor, Department of Orthopaedics, University of North Carolina, Chapel Hill, North Carolina

John W. Sperling, MD, MBA, Professor of Orthopedic Surgery, Mayo Clinic, Rochester, Minnesota

Mark Stanley, MD, Staff Radiologist, Department of Radiology, Naval Medical Center San Diego, San Diego, California

Eric J. Strauss, MD, Assistant Professor, Division of Sports Medicine, New York University Hospital for Joint Diseases, New York, New York

Hiroyuki Sugaya, MD, Director, Shoulder & Elbow Service, Funabashi Orthopaedic Sports Medicine Center, Funabashi, Chiba, Japan

Sam G. Tejwani, MD, Orthopaedic Sports Surgeon, Partner, Southern California Permanente Medical Group, Kaiser Permanente Hospital, Department of Orthopaedic Surgery, Division of Sports Medicine, Fontana, California

James E. Tibone, MD, Clinical Professor, Department of Orthopaedic Surgery, University of Southern California, Associate, Kerlan-Jobe Orthopaedic Clinic, Los Angeles, California

John M. Tokish, MD, Lt. Col. USAF MC, Residency Program Director, Tripler Army Medical Center, Honolulu, Hawaii

Suketu Vaishnav, MD, Fellow, The Steadman Clinic, Vail, Colorado

Geoffrey S. Van Thiel, MD, MBA, Sports Medicine Fellow, Department of Sports Medicine, Orthopaedic Surgery, Rush University Medical Center, Chicago, Illinois

Nikhil M. Verma, MD, Assistant Professor, Department of Orthopaedic Surgery, Division of Sports Medicine, Rush University Medical Center, Chicago, Illinois

James E. Voos, MD, Fellow, Sports Medicine and Shoulder Service, Hospital for Special Surgery, New York, New York

Gilles Walch, MD, Centre Orthopédique Santy, Unité Epaule, Lyon, France

Jon J.P. Warner, MD, Chief, Harvard Shoulder Service, Massachusetts General Hospital;, Professor of Orthopaedic Surgery, Harvard Medical School, Boston, Massachusetts

Russell F. Warren, MD, Professor of Orthopaedics, Weill Cornell Medical College, Surgeon in Chief Emeritus, Hospital for Special Surgery, New York, New York

Mathias Wellmann, MD, Resident Surgeon, Department of Shoulder and Elbow Surgery, ATOS Clinic Heidelberg, Heidelberg, Germany

Kevin E. Wilk, PT, DPT, Associate Clinical Director, Champion Sports Medicine, Physiotherapy Associates Clinic, Rehabilitation Consultant, Tampa Bay Rays Baseball Team, Tampa Bay, Florida;, American Sports Medicine Institute, Birmingham, Alabama

Michaelann Wilke, PhD, Alberta Institute for Human Nutrition, Department of Agricultural, Food and Nutritional Science, University of Alberta, 4-002B Li Ka Shing Centre for Health Research Innovation, Edmonton, Alberta, Canada

Nobuyuki Yamamoto, MD, PhD, Assistant Professor, Department of Orthopaedic Surgery, Tohoku University School of Medicine, Sendai, Miyagi, Japan

Allan A. Young, MBBS, MSpMed, PhD, FRACS (Orth), Shoulder Surgeon, Department of Orthopaedic and Traumatic Surgery, Royal North Shore Hospital, Sydney, Australia

Bojan Zoric, MD, Orthopaedic Surgery and Sports Medicine, Team Physician US Women"s National Soccer Team, Sports Medicine North, Peabody, Massachusetts

Matthias A. Zumstein, MD, Staff Member, Orthopedic Sports Medicine, Dept. of Orthopedic Surgery and Traumatology, University of Bern, Inselspital, Bern, Switzerland
Foreword
It is my great pleasure and privilege to write the foreword to this wonderful book. Since Arthur Sydney Blundell Bankart first put forth his concept of open stabilization of the shoulder at the turn of last century and Carter Rowe popularized this operation in the 1970s and 1980s in the United States, there has been a growing understanding of the complexity of shoulder instability. Most importantly, surgeons have developed an appreciation for the static and dynamic components of shoulder stability and the necessity to clearly define pathology prior to surgical intervention. Both editors of this unique book are well aware of the need to balance mobility and stability in order to restore healthy and powerful function to an unstable shoulder.
Dr. Provencher and Dr. Romeo are to be congratulated for organizing a current concepts book on management of shoulder instability which builds on the foundation of normal anatomy and biomechanics and considers treatment of all relevant pathology associated with these conditions. An A-list of international experts has been assembled to contribute to this book and has done so in a succinct, yet in-depth, fashion. Indeed, the individual chapters are both expansive and detailed and appropriately reinforce each other.
Their book is organized logically into five sections with the first providing a foundation of anatomy and principles of treatment. Based on conventional classification of shoulder instability, anterior and posterior instability as well as multidirectional instability are handled in a thoughtful fashion. One of the unique strengths of this book, however, is the attention given to management of revision problems. Indeed, this is one of the rare books which successfully illustrates important revision principles through case-based presentations. This strengthens the author’s message of thoughtful care and enhances the educational value for all surgeons.
Any orthopaedic surgeon who is faced with management of shoulder instability must have this book in his or her library. It is a resource which residents through experienced sports or shoulder specialists will use on a regular basis. Finally, it is my pleasure to call Dr. Provencher and Dr. Romeo both colleagues and friends. But the highest compliment I can pay them is that they are each a surgeon’s surgeon. Those who read this book and are successful in replicating the quality of care they offer their patients may one day achieve such a high compliment as well. As a result all our patients will benefit.

Jon J.P. Warner, MD, Chief, Harvard Shoulder Service, Massachusetts General Hospital;, Professor of Orthopaedic Surgery, Harvard Medical School, August 2011
Shoulder Instability: A Comprehensive Approach by Tony Romeo and Matt Provencher is not simply another book about shoulder instability. It is the definitive book on shoulder instability problems.
There are five sections and 43 chapters, all of them written by international experts in the field of shoulder instability.
The first section discusses anatomy, clinical examination, and classification of instability and is the first step to understanding and correctly treating patients.
The second and largest section discusses anterior instability. Seventeen chapters cover all aspects of diagnosis and treatment including nonoperative, arthroscopic, open, and postoperative. A particular emphasis is placed on the crucial topic of anterior glenoid bone loss with eight chapters discussing this fascinating problem for both arthroscopic and open surgeons.
The third section is about posterior instability. This section is often left out of books because it is rarer than anterior instability and because diagnosis and treatment are often confusing. With six chapters discussing this topic, the authors help to perfectly describe preoperative clinical and radiological evaluations for both open and arthroscopic treatment.
Section four is dedicated to the controversial topic of Multidirectional Instability. After the “princeps” description of this pathology by Charles Neer, the exact limits are still unclear. The editors asked a European team to describe the clinical history, examination, and arthroscopic findings before having American leaders address rehabilitation for both open and arthroscopic treatment.
The fifth section may be the most interesting since it deals with all the problems often neglected in instability: preoperative and postoperative arthritis, associated subscapularis and rotator cuff tears, failures of surgical treatment, chronic dislocations, and associated biceps pathology. The ten chapters in this section are written by the most distinguished authors, all of them recognized for their particular expertise about these special topics.
In all, this book is fascinating. It will help residents and fellows learn all aspects of shoulder instability. It will also help the physiotherapist, the sports medical doctor, and the radiologist to approach their patients with a better understanding of the principles regarding instability of the shoulder joint. The surgeons, of course, will benefit more than everybody else from this book and will find all the options available to treat patients looking for shoulder stability.
Finally, the two editors, Anthony Romeo and Matt Provencher, must be commended for their tremendous work putting together such a renowned international faculty for an outstanding contribution on the comprehensive treatment of shoulder instability.

Gilles Walch, MD, Centre Orthopédique Santy, Unité Epaule, Lyon, France
Preface
Shoulder instability remains an important topic in the realm of shoulder conditions and has enjoyed a renewed interest in both arthroscopic and open management strategies. The goal behind writing Shoulder Instability: A Comprehensive Approach was to assemble in one textbook location the principles, pathology, and management strategies for the care of the patient with shoulder instability. It is designed to be a user-friendly, clinically relevant textbook containing useful information for caring for patients with all types of shoulder instability.
The textbook is organized into several different sections starting with evaluation and then progressing to diagnosis and both non-surgical and surgical management of anterior, posterior, and multidirectional shoulder instability. A unique aspect of the book is that other associated conditions such as concomitant rotator cuff tears, arthritis, and neurologic injuries are fully addressed. In addition, each section has a high emphasis on the surgical technique, with supporting illustrations and accompanying video. In order to assist surgeons with surgical management, a total of 890 original, full-color figures were introduced in this textbook to facilitate a step-by-step description of the procedures. Before describing the surgical technique under consideration, guidelines for arriving at the associated diagnosis and the indications for surgery are reviewed in multiple text boxes and bulleted format for ease of reading.
The authors describe every step of the procedure in a logical and methodical manner and also intersperse clinical and technical pearls to share with the reader their personal experience. We hope that these pearls will enable the surgeon who is learning a new technique to begin at a level of performance higher on the learning curve than otherwise would be possible. From patient history, examination, and radiographic workup to exact arthroscopic and open shoulder instability surgical steps, we hope that you will find this text easy to follow with step-by-step instructions and surgical guidelines. The level of detail in the textbook was designed to be applicable to not only practicing orthopaedic surgeons, fellows, residents, and students in orthopaedic surgery, but also to be particularly useful for physician assistants, physical therapists, and trainers who care for the patient with shoulder instability.
Finally, we are deeply indebted to our world-renowned international contributors who are experts in the treatment of shoulder instability for their incredible voluntary efforts in assembling user-friendly yet clinically robust content. The success of this project would not have been possible without their expert contributions.
We hope that you find Shoulder Instability: A Comprehensive Approach a valuable reference to aid in your care of the patient with shoulder instability.
Acknowledgments
This textbook would not have been possible without the tireless efforts of both Dan Pepper and Virginia Wilson from Elsevier. Without their persistence and dedication to the project, we would not have been able to publish this timely text. We would also like to acknowledge the professional staff at Elsevier who provided timely and valuable editing assistance. In addition, we are deeply indebted to all of our expert contributors who have truly made this book an important contribution as a comprehensive textbook of shoulder instability.
Video contents

Anterior instability
Apprehension Maneuver
Chapter 6, Video 1 – William N. Levine
Relocation Maneuver
Chapter 6, Video 2 – William N. Levine
Anterior Release Test
Chapter 6, Video 3 – William N. Levine
Active Compression Test
Chapter 6, Video 4 – William N. Levine
Arthroscopic Bankart Repair
Chapter 11, Video 1 – Robert A. Arciero
Arthroscopic Bony Bankart Repair
Chapter 15, Video 1 – Hiroyuki Sugaya
Arthroscopic Iliac Bone Grafting
Chapter 15, Video 2 – Hiroyuki Sugaya

Posterior instability
Loss of Chondrolabral Containment
Chapter 24, Video 1 – Seung-Ho Kim
The Kim Lesion 1
Chapter 24, Video 2a – Seung-Ho Kim
The Kim Lesion 2
Chapter 24, Video 2b – Seung-Ho Kim
The Kim Lesion 3
Chapter 24, Video 2c – Seung-Ho Kim
The Jerk Test
Chapter 24, Video 3 – Seung-Ho Kim
The Kim Test
Chapter 24, Video 4 – Seung-Ho Kim
The Kim Posterior Portal
Chapter 24, Video 5 – Seung-Ho Kim
The Transcuff Superior Portal
Chapter 24, Video 6 – Seung-Ho Kim
Surgical Technique of the Arthroscopic Capsulolabroplasty
Chapter 24, Video 7 – Seung-Ho Kim
Diagnostic Arthroscopy – Right Shoulder
Chapter 26, Video 1 – James P. Bradley and Sam G. Tejwani
Rotator Cuff Undersurface Debridement
Chapter 26, Video 2 – James P. Bradley and Sam G. Tejwani
Posterior Labral Tear Visualization
Chapter 26, Video 3 – James P. Bradley and Sam G. Tejwani
Glenoid Preparation with Shaver
Chapter 26, Video 4 – James P. Bradley and Sam G. Tejwani
Posterosuperior Tear Visualization and Anchor Guide Needle Localization
Chapter 26, Video 5 – James P. Bradley and Sam G. Tejwani
Posterosuperior Anchor #1 Placement
Chapter 26, Video 6 – James P. Bradley and Sam G. Tejwani
Posterosuperior Anchor #2 Placement
Chapter 26, Video 7 – James P. Bradley and Sam G. Tejwani
Posterosuperior Anchor #1 Suture Shuttling – Step 1
Chapter 26, Video 8 – James P. Bradley and Sam G. Tejwani
Posterosuperior Anchor #1 Suture Shuttling – Step 2
Chapter 26, Video 9 – James P. Bradley and Sam G. Tejwani
Posterosuperior Anchor #2 Suture Shuttling – Step 1
Chapter 26, Video 10 – James P. Bradley and Sam G. Tejwani
Posterosuperior Anchor #2 Suture Shuttling – Step 2
Chapter 26, Video 11 – James P. Bradley and Sam G. Tejwani
Posterosuperior Anchor #2 Weston Knot Tied Through Posterior Portal
Chapter 26, Video 12 – James P. Bradley and Sam G. Tejwani
Posterosuperior Anchor #1 Weston Knot Tied Through Posterior Portal
Chapter 26, Video 13 – James P. Bradley and Sam G. Tejwani
Posteroinferior Labrum Limited Flap Debridement
Chapter 26, Video 14 – James P. Bradley and Sam G. Tejwani
Posterior Capsulolabral Mobilization with Chisel
Chapter 26, Video 15 – James P. Bradley and Sam G. Tejwani
Posteroinferior Anchor #1 Placement - Most Inferior Anchor First
Chapter 26, Video 16 – James P. Bradley and Sam G. Tejwani
Posteroinferior Anchor #1 Suture Shuttling – Step 1
Chapter 26, Video 17 – James P. Bradley and Sam G. Tejwani
Posteroinferior Anchor #1 Suture Shuttling – Step 2
Chapter 26, Video 18 – James P. Bradley and Sam G. Tejwani
Posteroinferior Anchor #1 Weston Knot Tied Through Posterior Portal
Chapter 26, Video 19 – James P. Bradley and Sam G. Tejwani
Anchor #4 Placement
Chapter 26, Video 20 – James P. Bradley and Sam G. Tejwani
Anchor #5 Placement and Completed Weston Knot
Chapter 26, Video 21 – James P. Bradley and Sam G. Tejwani
Final Posterior Capsulolabral Repair
Chapter 26, Video 22 – James P. Bradley and Sam G. Tejwani
Posterior Portal Closure – Step 1
Chapter 26, Video 23 – James P. Bradley and Sam G. Tejwani
Posterior Portal Closure – Step 2
Chapter 26, Video 24 – James P. Bradley and Sam G. Tejwani

Extensive labral tears
Estimating Bone Loss
Chapter 36, Video 1 – Daniel J. Solomon, Ian Lo, and John M. Tokish
Diagnostic Arthroscopy
Chapter 36, Video 2 – Daniel J. Solomon, Ian Lo, and John M. Tokish
Mobilizing the Labrum
Chapter 36, Video 3 – Daniel J. Solomon, Ian Lo, and John M. Tokish
Repairing the Labrum and Inferior Glenohumeral Ligament (IGHL)
Chapter 36, Video 4 – Daniel J. Solomon, Ian Lo, and John M. Tokish
Final Repair
Chapter 36, Video 5 – Daniel J. Solomon, Ian Lo, and John M. Tokish
Completed Repair
Chapter 36, Video 6 – Daniel J. Solomon, Ian Lo, and John M. Tokish
Table of Contents
Instructions for online access
Front matter
Copyright
Dedication
Contributors
Foreword
Preface
Acknowledgments
Video contents
Section 1: Anatomy and Principles of Treatment
Chapter 1: Clinical anatomy and biomechanics of the glenohumeral joint (including stabilizers)
Chapter 2: Examination and classification of instability
Chapter 3: Beach chair and lateral decubitus setup—pros and cons
Chapter 4: Open and arthroscopic instrumentation for instability repair
Chapter 5: Sutures and glenoid anchors for instability
Section 2: Anterior Instability
Chapter 6: Findings and pathology associated with anterior shoulder instability
Chapter 7: Clinical history and physical examination
Chapter 8: Radiographic studies and findings
Chapter 9: Nonoperative treatment of anterior shoulder instability
Chapter 10: Nonoperative rehabilitation for traumatic and atraumatic glenohumeral instability
Chapter 11: Arthroscopic treatment of anterior instability—surgical technique
Chapter 12: Open treatment of anterior instability—surgical technique
Chapter 13: Biomechanics of glenohumeral bone loss and treatment mechanics
Chapter 14: Radiographic and arthroscopic evaluation of glenoid and humeral head bone loss
Chapter 15: Arthroscopic treatment of glenoid bone loss—surgical technique
Chapter 16: Open bony augmentation of glenoid bone loss—the latarjet and variants—surgical technique
Chapter 17: The latarjet procedure—technique and fixation constructs
Chapter 18: Technique of arthroscopic bristow-latarjet-bankart procedure: the 2b3 procedure
Chapter 19: Open bony augmentation of glenoid bone loss—iliac crest and allograft—surgical technique
Chapter 20: Humeral head defects—biomechanics, measurements, and treatments
Chapter 21: Recent advances in the diagnosis and treatment of glenohumeral bone loss
Chapter 22: Rehabilitation: return-to-play and in-season guidelines
Section 3: Posterior Instability
Chapter 23: Pathology and biomechanics of posterior instability
Chapter 24: Posterior instability: clinical history, examination, and surgical decision making
Chapter 25: Imaging findings in posterior instability
Chapter 26: Arthroscopic treatment of posterior instability—surgical technique
Chapter 27: Open surgical solutions for posterior instability of the shoulder
Chapter 28: Rehabilitation after posterior instability repair—open vs. arthroscopic
Section 4: Multidirectional Instability
Chapter 29: Pathology and findings in patients with multidirectional instability
Chapter 30: Clinical history, examination, arthroscopic findings, and treatment of multidirectional instability
Chapter 31: Nonoperative management and scapular dyskinesis
Chapter 32: Arthroscopic treatment of multidirectional instability—surgical technique
Chapter 33: Open treatment of multidirectional instability—surgical technique
Section 5: Revision Instability and Special Topics
Chapter 34: Instability treatment failure—common reasons and prevention
Chapter 35: Rotator interval—considerations and techniques for instability
Chapter 36: Extensive labral tears—pathology and surgical treatment
Chapter 37: Nerve injuries with instability procedures—prevention and management
Chapter 38: Subscapularis deficiency after shoulder instability procedures—prevention and management
Chapter 39: Recurrent instability due to capsular deficiency
Chapter 40: Glenohumeral stiffness and arthritis after instability surgery—causes and treatment
Chapter 41: Recognition and management of combined instability and rotator cuff tears
Chapter 42: The patient with hyperlaxity and shoulder instability—ehlers-danlos and other disorders
Chapter 43: Management of chronic shoulder dislocations
Index
Section 1
Anatomy and Principles of Treatment
CHAPTER 1 Clinical anatomy and biomechanics of the glenohumeral joint (including stabilizers)

Thay Q. Lee, PhD

Key points

Anatomy and Biomechanics: The glenohumeral joint provides the largest range of motion among all diarthrodial joints but also has the greatest propensity for instability. The glenohumeral joint has six degrees of freedom of motion, which can be described by three rotations and three translations with respect to the anatomic coordinate system.
Passive Bony Stabilizers: The bony passive stabilizers include the glenoid, humeral head, and the proximal humerus. The glenohumeral articulation is minimally constrained and thus permits both rotations and translations. This results from the unique and variable anatomy of the proximal humerus, including the humeral head and the glenoid. For anatomic restoration, the extreme variability of the osseous anatomy necessitates an individualized anatomic bony restoration approach to create the most favorable environment for soft tissue function.
Passive Soft Tissue Stabilizers: The passive soft tissue stabilizers include the glenoid labrum, the glenohumeral ligaments, and the glenohumeral joint capsule. These soft tissue stabilizers help limit glenohumeral joint motion for both rotation and translation in a position dependent manner. This is due to a complex and variable anatomy of each structure accommodating its intricate role as a primary stabilizer, as well as a secondary stabilizer, depending on the arm position. With current arthroscopic techniques and a deeper understanding of the pathoanatomy, accurate restoration of the anatomy, stability, and the path of glenohumeral articulation are possible to improve shoulder function.
Active Stabilizers: Active soft tissue stabilizers are muscle-tendon complexes that provide both function and stability to the shoulder. The active stabilizers include the tendons and the muscles of the rotator cuff, biceps, deltoid, pectoralis major, and the latissimus dorsi. The muscles provide stability to the shoulder by concavity compression and a barrier effect. With their strong influence on shoulder stability, it is also important to note that the muscles may contribute both to stabilization of the joint and to instability and dislocation of the joint. Therefore, the muscle-tendon complexes provide both function and stability to the shoulder while simultaneously providing a large range of motion.
The glenohumeral joint motion is a result of a complex interplay between the passive and active stabilizers that require intricate balance and synchronicity. The active and passive soft tissue and bony stabilizers work together to provide glenohumeral stability.
Laxity is a normal finding in the glenohumeral joint to allow for extensive motion in multiple planes. However, pathologic laxity can lead to the clinical condition of instability.
Acromioclavicular Joint: The acromioclavicular ligaments help stabilize anterior and posterior horizontal translations. The coracoclavicular ligaments prevent excessive superior translation across the acromioclavicular joint. The stability provided by each of these ligaments is believed to be critical in restoring the anatomy after a destabilizing acromioclavicular dislocation.

Introduction
The glenohumeral joint provides the largest range of motion among all diarthrodial joints but also has the greatest propensity for instability. The glenohumeral joint has six degrees of freedom of motion that can be described by three rotations and three translations with respect to the anatomic coordinate system ( Fig. 1-1 ). The plane of elevation is defined relative to the coronal plane perpendicular to the transverse plane. Abduction is described as the angle of elevation in this plane. The rotation of the humerus around its long axis is described as internal and external rotation relative to its anatomic neutral position. The translations of the glenohumeral joint can be described by the amount of the translation in anterior-posterior, superior-inferior, and medial-lateral directions. The glenohumeral joint motion is a result of a complex interplay between the passive and active stabilizers that require intricate balance and synchronicity. This chapter addresses the anatomy and biomechanics, especially the recently acquired knowledge, pertaining to diagnoses and treatments frequently encountered by the shoulder surgeon. In addition, the anatomy and biomechanics are described from their functional perspective as passive and active stabilizers. The bony passive stabilizers include the glenoid, humeral head, and the proximal humerus. The soft tissue passive stabilizers include the glenoid labrum, the glenohumeral ligaments, and the glenohumeral joint capsule. The active stabilizers include the tendons and the muscles of the rotator cuff, biceps, deltoid, pectoralis major, and the latissimus dorsi.

FIGURE 1-1 The glenohumeral joint has six degrees of freedom of motion that can be described by three rotations and three translations with respect to the anatomic coordinate system.
(Redrawn and colorized; original drawing provided by Angie Lee.)

Anatomy and biomechanics

Passive bony stabilizers
The bony passive stabilizers include the glenoid, humeral head, and proximal humerus ( Fig. 1-2 ). Glenohumeral articulation is minimally constrained and thus permits both rotations and translations. This inherent instability of the glenohumeral joint is reflected by the fact that only 25% to 30% of the humeral head is in contact with the glenoid surface at any given anatomic position. 1 - 3 This dimensional relationship between the humeral head and the glenoid, referred to as the glenohumeral index, can be calculated as the maximum diameter of the glenoid divided by the maximum diameter of the humeral head ( Figs. 1-3 and 1-4 ). It has been reported that this ratio is approximately 0.75 and 0.6 in the sagittal plane and transverse plane, respectively. 4 These authors also reported that the contact area moves superiorly with elevation. 4 More recently, it has been reported that there was a slight articular mismatch in adduction but that the glenohumeral joint became more congruent and stable in abduction. 5 The contact area shifts from an inferior region to a superior and central-posterior region, whereas the glenoid contact area shifts posteriorly. 6 , 7

FIGURE 1-2 Bony passive stabilizers. The glenoid, humeral head and proximal humerus are shown. Note the large semiellipsoidal humeral head and a small shallow glenoid.
(Redrawn and colorized; original drawing provided by Angie Lee.)

FIGURE 1-3 The effective glenoid arc is the arc of the glenoid able to support the net humeral joint reaction force. The balance stability angle is the maximal angle that the net humeral joint reaction force can make with the glenoid center line before dislocation occurs. The shape of the bone, cartilage, and labrum all contribute to the effective glenoid arc and the balance stability angle.
(From Rockwood CA, et al: The shoulder, ed 4, Philadelphia, 2010, Saunders.)

FIGURE 1-4 The deltoid and cuff muscle forces (dotted arrows) maintain the net humeral joint reaction force (solid arrow) within the balance stability angle (dotted lines).
(Modified from Matsen FA, III, et al: Practical evaluation and management of the shoulder, Philadelphia, 1994, WB Saunders.)
To characterize bony stability, Lippitt et al 8 defined the “stability ratio” as the force necessary to dislocate the humeral head from the glenoid divided by the compressive load. This stability ratio is dependent on the concavity of the glenoid and therefore increases with higher glenoid depths ( Fig. 1-5 ). The labrum also contributes to stability as the stability ratio decreases by approximately 20% after the labrum is removed, and it further decreases after creating a chondrolabral defect. 9 More recently, Halder et al 10 reported the average stability ratios with and without the labrum according to the anterior-posterior and superior-inferior directions ( Fig. 1-6 ). These authors reported that the stability ratio was greatest in the inferior direction and was greater with the arm in adduction compared to abduction. The average contribution of the labrum to the stability was 10%. The aforementioned minimally constrained glenohumeral articulation results from the unique and variable anatomy of the proximal humerus, including the humeral head and the glenoid. The following sections describe the bony stabilizers with respect to specific anatomy.

FIGURE 1-5 The load and shift test. The adequacy glenoid concavity in a given direction can be assessed by compressing the humeral head into the glenoid concavity and noting the amount of displacing force necessary to translate the head. The articular stability of the glenohumeral joint is enhanced or lessened according to variation in articular congruence.
(Redrawn and colorized; original drawing provided by Angie Lee.)

FIGURE 1-6 The balance stability angle varies around the face of the glenoid. For a normal glenoid, the superior and inferior balance stability angles are greater than the anterior and posterior balance stability angles. This figure shows the balance stability angles (solid arrows) measured in eight directions around the face of the glenoid. Values are means for 10 cadaver shoulders with a compressive load of 50 N.
(Modified from Matsen FA, III, et al: Practical evaluation and management of the shoulder, Philadelphia, 1994, WB Saunders.)

Proximal humerus
The proximal humerus includes an ellipsoidal humeral head covered with hyaline articular cartilage. The anatomic neck consists of a bony transition from cartilage to capsular attachment and tendinous insertion. The tuberosities are located lateral to the anatomic neck. The lesser tuberosity contains the subscapularis insertion, and the greater tuberosity, which has superior, middle, and inferior facets, contains the supraspinatus, infraspinatus, and teres minor insertions. 11 The insertions on these tuberosities create an interconnected cuff of tendons that surrounds the humeral head. The transition point to the humeral shaft, just distal to the tuberosities, marks the surgical neck. The bicipital groove is flanked by both tuberosities and provides a stabilizing path for the long head of the biceps tendon ( Fig. 1-7 ).

FIGURE 1-7 A drawing showing the bicipital groove, which is covered by the transverse humeral ligament (TL) consists of transverse fibers of the capsule extending between the greater tuberosity (GT) and the lesser tuberosity (LT). These structures contain the long head of the biceps tendon.
(From Reider B, et al: Operative techniques, sports medicine surgery, Philadelphia, 2010, Saunders.)
The morphologic measurements of the proximal humerus vary greatly due to size variations. Robertson et al 12 reported the intramedullary and extramedullary morphology of 30 pairs of proximal humeri. Head retroversion averaged 19 degrees (range, 9 to 31 degrees); head inclination, or neck-shaft angle, averaged 41 degrees (range, 34 to 47 degrees); head radius averaged 23 mm (range, 17 mm to 28 mm); head thickness averaged 19 mm (range, 15 mm to 24 mm); medial head center offset averaged 7 mm (range, 4 mm to 12 mm); and posterior head center offset averaged 2 mm (range, 1 mm to 8 mm) ( Fig. 1-8 ). These extreme variations in proximal humeral anatomy suggest the importance of recognizing the patient specific anatomic geometry of the proximal humerus. For example, restoring the correct prosthetic anatomy during arthroplasty has significant clinical implications for range of motion, kinematics, and impingement. 13 Specifically, inferior malpositioning of more than 4 mm can create increased subacromial contact, and an offset of 8 mm in any direction compromises passive range of motion. Minimizing subacromial contact and maximizing glenohumeral motion after humeral head replacement can be achieved with anatomic reconstruction of the humeral head–humeral shaft offset to within 4 mm.

FIGURE 1-8 Drawing of the proximal humerus showing the humeral head inclination and retroversion.
(Redrawn and colorized; original drawing provided by Angie Lee.)
For surgeons, this anatomic variation of proximal humerus must be carefully considered. In order for a surgeon to consistently orient the anatomic geometry of the proximal humerus, the bicipital groove is commonly used during surgery as a bony landmark of the proximal humerus. 14 , 15 In a computed tomography (CT) analysis of embalmed cadavers, the bicipital groove was measured at both the anatomic and surgical necks relative to the transepicondylar axis at the elbow. 14 , 15 As the bicipital groove coursed distally, it was found to internally rotate; the mean change in rotation was 15.9 degrees (SD ± 6.8 degrees; range, 4 to 32 degrees). A similar study found a 9.3 degrees difference (range, 3 to 22.5 degrees) between the bicipital groove at the anatomic neck and the surgical neck. 14 The shoulder surgeon must carefully consider this variability whenever the bicipital groove is used as a landmark in humeral head replacement. It is a particularly relevant factor during humeral head replacement involving a three-part or four-part fracture, when the proximal bicipital groove often cannot be used as a reliable anatomic landmark. Placing the lateral fin of the prosthesis either 9 mm or 12 mm posterior to the bicipital groove at the anatomic neck has been recommended. 16 , 17 However, using the bicipital groove at the surgical neck as an anatomic landmark may create excessive retroversion of the humeral head. Therefore, bicipital groove anatomy is only a potential guide when individualizing anatomic restoration during arthroplasty.
The anatomic restoration of the tuberosities is very important for restoring shoulder function. Although the bicipital groove stabilizes the long head of the biceps tendon, the tuberosities that flank the groove determine the rotator cuff length and tension relationships which are responsible for shoulder function. This importance of restoring tuberosity anatomy has been supported by biomechanical studies. 18 , 19 Medial-to-lateral tuberosity displacement in a four-part fracture model altered kinematics and increased the torque necessary to externally rotate the humerus 50 degrees. 18 This finding is relevant to the use of the bicipital groove as a landmark for prosthesis placement because after the prosthesis orientation is determined, the tuberosity position is obligatory. In another four-part fracture model, 10 mm of inferior tuberosity placement resulted in significantly more superior glenohumeral force displacement, which suggests a compromise in the mechanical advantage of abduction. 19 These studies provide a biomechanical rationale for optimizing the restoration of proximal humeral anatomy during arthroplasty, which can be difficult with a four-part fracture. For anatomic restoration of the proximal humerus, the extreme variability of the osseous proximal humerus anatomy necessitates an individualized anatomic bony restoration approach to create the most favorable environment for soft tissue function.

Glenoid
The glenoid functions as the shallow socket of the glenohumeral joint on the lateral side of the scapular body. The glenoid is pear shaped, with a wider inferior half ( Fig. 1-9 , A ); on average, the size and the shape vary widely. The glenoid is inclined and retroverted by a small amount, again with large variations. The average superior-inferior dimension of the glenoid was reported to be 39 mm (± 3.7 mm; range, 30 mm to 48 mm); the anteroposterior dimension of the lower half of the glenoid averaged 29 mm (± 3.1 mm; 21 mm to 35 mm); and the anteroposterior dimension of the upper half at its midpoint averaged 23 mm (± 2.7 mm; 18 mm to 30 mm). The ratio of the anteroposterior dimension of the lower half of the glenoid to that of the upper half was 1:0.8 (± 0.01). 20 The average inclination and the retroversion of the glenoid has been reported to be 4.2 degrees (range −7 to 15.8 degrees; a positive value denotes a superior inclination, and a negative value, an inferior inclination) and 1.23 degrees (± 3.5 degrees; range, 9.5 degrees anteverted to 10.5 degrees retroverted), respectively 21 ( Figs. 1-9 , B –1-9, D ). The glenoid anatomy, as with other structures in the shoulder, varies greatly among individuals.

FIGURE 1-9 A, Pear-shaped glenoid with a wider inferior half. B, Scapular and glenoid version. The scapula is oriented 30 to 45 degrees anterior to the coronal plane. C, Glenoid fossa’s retroversion. D, Glenoid fossa’s superior tilt.
( A from Reider B, et al: Operative techniques, sports medicine surgery, Philadelphia, 2010, Saunders.)
For surgeons, the complex and variable anatomy of the glenoid presents a challenge in the face of pathologic bone loss for reconstruction procedures such as in shoulder arthroplasty. Recently, the effect of glenoid malpositioning on humeral head stability was reported. 22 In this study, the glenoid component was retroverted 15 degrees to simulate the posterior glenoid bone loss often seen with osteoarthritis, and modular components were used to test the proximal humeral stem in anatomic and 15 degrees anteversion. The findings showed that because an anteverted humeral component could not stabilize the shoulder or compensate for a severely retroverted glenoid, reaming the glenoid to neutral version might be preferable to altering humeral version. However, it is unknown whether these findings would be altered by the presence of a patulous posterior capsule, which is often encountered in conjunction with posterior glenoid bone loss. More recently, a study using a three-dimensional finite element model of the shoulder concluded that glenoid retroversion greater than 10 degrees can lead to major biomechanical alterations and possibly increase the risk of loosening. 23 This was further supported by a cadaveric study. 24 Therefore, a surgeon should consider forgoing glenoid resurfacing if retroversion cannot be corrected below 10 degrees ( Fig. 1-10 ).

FIGURE 1-10 Glenoid hypoplasia. When the glenoid rim is hypoplastic, it cannot contribute normally to the glenoidogram.
(From Matsen FA, III, et al: Shoulder surgery: Principles and procedure, Philadelphia, 2004, WB Saunders, p 111.)
The pathoanatomy of osteoarthritis can lead to posteroinferior glenoid erosion and wear. Posterior glenoid wear, as shown on transverse-plane imaging, is a recognized measure of pathoanatomy that must be considered when performing arthroplasty. 25 , 26 Glenoid inclination, as seen in the coronal plane, is another useful tool for surgical decision making. Standard radiographs of 100 consecutive patients with primary osteoarthritis were compared with radiographs of 100 otherwise healthy patients with shoulder pain. Inferior glenoid erosion was classified by degree of inclination to represent increasing inferior glenoid wear. In type 0, the mean angle of inclination was 1.7 degrees (range, 7 to 7 degrees); in type I, 7.1 degrees (16 to 2 degrees); in type II, 16 degrees (32 to 5 degrees); and in type III, 17.7 degrees (28 to 12 degrees). These authors recommended normalizing type II and type III glenoid inclination as well as retroversion of more than 15 degrees for glenoid replacement. 27 However, excessive medialization should be avoided. For anatomic restoration of the glenoid, again, the extreme variability of the anatomy necessitates an individualized anatomic bony restoration approach to create the most favorable environment for soft tissue function.

Passive soft tissue stabilizers
The passive soft tissue stabilizers include the glenoid labrum, glenohumeral ligaments, and the glenohumeral joint capsule ( Figs. 1-11 and 1-12 ). These soft tissue stabilizers help limit glenohumeral joint motion for both rotation and translation in a position dependent manner. The complex anatomy of each structure accommodates their complex role as a primary stabilizer, as well as a secondary stabilizer, depending on the glenohumeral position. The following sections describe the passive soft tissue stabilizers with respect to specific anatomy.

FIGURE 1-11 Soft tissue stabilizers including the glenoid labrum, glenohumeral ligaments, and the glenohumeral joint capsule.
(Redrawn and colorized; original drawing provided by Angie Lee.)

FIGURE 1-12 Anteroposterior views of the orientation of the glenohumeral (GH) ligaments in external rotation as a function of shoulder position. A, Superior glenohumeral ligament. B, Middle glenohumeral ligament. C, Inferior glenohumeral ligament. D and E, The capsule.
(Modified from Turkel SJ , et al: Stabilizing mechanisms preventing anterior dislocation of the glenohumeral joint. J Bone Joint Surg Am 63:1208–1217, 1981.)

Inferior glenohumeral ligament complex (ighlc)
The inferior glenohumeral ligament (IGHL) is the most important anterior stabilizer in 90° of abduction and external rotation. 28 This was corroborated by the strain measurement in the anterior band, which was tight in abduction and external rotation, whereas the posterior band was tight in abduction and internal rotation. 29 The anterior band also was reported to be the primary anterior stabilizer when the arm was in abduction in the scapular plane, and the posterior band was the primary posterior stabilizer when the arm was horizontally adducted. 30
Anatomically, the IGHL is attached to the glenoid in the 7-to-9 or 3-to-5 clock-face positions. The collagen fibers are directly affixed to the rigid fibrocartilaginous labrum and more medially to the periosteum along the glenoid neck. The anterior band is an anterior thickening of the IGHL. A posterior capsular thickening or band is present in 63% of specimens. 31 The IGHL attachment on the glenoid side has been reported to have two types of insertions 32 ( Fig. 1-13 ). In this study of 10 shoulders, 2 out of 10 specimens had labral dominant insertion where the IGHL is directly attached to the labrum, and 8 out of 10 specimens had glenoid neck dominant insertion where the IGHL is attached to both the labrum and the glenoid neck. These two insertion types may influence arthroscopic repair of Bankart lesion as the lesion on the glenoid neck cannot be visualized during an arthroscopic repair.

FIGURE 1-13 Histologic photograph showing the two types of IGHL attachment on the glenoid side. A, Labral dominant insertion where the IGHL is directly attached to the labrum. B, Glenoid neck dominant insertion where the IGHL is attached to both the labrum and the glenoid neck.
The IGHL attachment on the humeral side has two attachment geometries: the split type (58%) and the broad type (42%). 33 Both extend inferiorly 2 cm from the articular surface at approximately the 4 o’clock and 8 o’clock positions. The split type is a capsular bifurcation having internal and external folds with an interposed loose connective tissue. The broad type does not have separate folds. Failure to release the external fold may tether the capsular pouch in a patient with multidirectional instability. Releasing the entire capsule from the humeral attachment, particularly posteriorly, may be necessary during a capsulorrhaphy.
The tissue between the anterior and posterior capsular thickenings is a hammocklike structure where the glenoid labrum and humerus act as posts that swing or rotate with humeral rotation to help provide passive stability with reciprocal load sharing. During abduction and external rotation, the anterior complex resists anterior translation; during abduction and internal rotation, the posterior complex resists posterior translation. This position-specific function of the glenohumeral joint capsule is due not only to the anatomy of the glenohumeral joint capsule but also originates from a complex asymmetric humeral head articulation resulting from humeral head offset, humeral head retroversion, and humeral neck-shaft angle.
The biomechanical characteristics of the three IGHLC anatomic regions (superior band, anterior axillary pouch, and posterior axillary pouch) were quantified by tensile testing of bone-ligament-bone complexes highlighting the significance of permanent stretching of the capsule. 34 However, in an isolated Bankart lesion, only minor humeral head translation was observed, 35 suggesting that IGHLC plastic deformations exist for pathologic recurrent instability. Another study reported unrecoverable IGHLC strain as a result of cyclic loading and thereby supported the hypothesis that repeated subfailure strain results in an overuse injury. 36 Testing of IGHLC in the apprehension position (abduction and external rotation) showed that unrecoverable capsular elongation was greatest in the ligament midsubstance (mean, 0.53 mm) and smallest at the humeral insertion (mean, 0.04 mm). 37 The low absolute strain values suggest that only slight plication of the anteroinferior capsulolabral structures may be necessary to restore capsular anatomy after a primary instability injury ( Figs. 1-14 and 1-15 )

FIGURE 1-14 Glenohumeral translation is movement of the center of the humeral head with respect to the face of the glenoid. A, The humeral head in mid-glenoid with lax ligaments. B, The amount of translation allowed (black arrow) is determined by the initial position of the joint and the length of the ligament that becomes tight (red arrows).
(From Rockwood CA, et al: The shoulder, ed 4, Philadelphia, 2010, Saunders.)

FIGURE 1-15 Glenohumeral rotation is movement of the humerus around the center of the humeral head, which remains centered in the glenoid fossa. A, The humeral head in mid-glenoid with lax ligaments. B, The amount of rotation allowed (red arrow) in response to an applied torque (black arrow) is determined by the initial position of the joint and the length of the ligament that becomes tight.
(From Rockwood CA, et al: The shoulder, ed 4, Philadelphia, 2010, Saunders.)


Pearl
The anterior band of the IGHL acts as a restraint to anterior translation, especially in abduction and external rotation. Injury to the anterior band of the IGHL occurs usually in the midsubstance and is irreversible elongation that needs to be addressed surgically for optimal results for instability repair.
For functional characteristics of the IGHLC, glenohumeral translation and external rotation have been investigated with respect to IGHL length in a cadaver instability model 38 ( Fig. 1-16 ). The cadaver shoulder instability model was created by nondestructively stretching the glenohumeral joint capsule to 10%, 20%, and 30% in constrained humeral rotation beyond maximum humeral external rotation at 90 degrees of glenohumeral abduction in the scapular plane with 90 degrees of humeral rotation ( Fig. 1-17 ). These authors reported that nondestructive excessive external rotational stretching resulted in a significant increase in superior (30%, 3.3 mm) and inferior (30%, 2.3 mm) length of the anterior band of the IGHL; external rotation (30%, 35 degrees); and anterior (30%, 2.4 mm), inferior (30%, 2.2 mm), and anterior-posterior (30%, 5.1 mm) translations. There were significant positive linear correlations between the length of the anterior band of the inferior glenohumeral ligament, external rotation, and anterior translation. This study demonstrated a strong correlation between the length of the IGHL and anterior-posterior glenohumeral translation and humeral rotational range of motion at 90 degrees of glenohumeral abduction in the scapular plane with 90 degrees of humeral rotation. 38 Using this model, Alberta et al 39 compared intact shoulders, shoulders with simulated anterior instability by capsular stretching, and shoulders after 10-mm anteroinferior arthroscopic suture plication. Arthroscopic plication, which involved doubling the effective bumper height of the labrum, was found to be effective in reducing anterior translation and external rotation while shifting the glenohumeral center of rotation posteriorly and inferiorly. These findings suggest that arthroscopic techniques have the potential to restore the translational stability but alter the path of glenohumeral articulation. Additional studies are required to increase understanding of surgical restoration of anatomic tension after traumatic or overuse injuries.

FIGURE 1-16 If the humerus is rotated beyond the point at which the ligaments become tight, the displacing force (P) can push the humeral head out of the glenoid center, a phenomenon known as obligate translation.
(Modified from Matsen FA, III, et al: Practical evaluation and management of the shoulder, Philadelphia, 1994, WB Saunders.)

FIGURE 1-17 The photographs show nondestructive stretching of the IGHL in human cadaver shoulders for simulating anterior laxity of the glenohumeral joint.
The IGHLC, with its variable anatomy, provides a passive restraint to excessive humeral head translation. Its function is dependent on the arm position. Arthroscopic techniques have the potential to restore normal passive stabilizing function but not the path of glenohumeral articulation, and a deeper understanding of the pathoanatomy will lead to improving treatment strategies to restore normal function.

Superior labrum
The labrum is a triangular rim of fibrocartilaginous tissue surrounding the glenoid (see Fig. 1-13 ). The labrum deepens the socket by an average of 9 mm in the superior-inferior dimension and 5 mm in the anteroposterior plane, which represents as much as 50% of the glenoid socket depth. 40 The labrum provides some passive stability to the humeral head. Superiorly, the long head of the biceps tendon (LHBT) shares its origin with labral tissue and the supraglenoid tubercle (see Fig. 1-13 ). Appreciation of anatomic labral variation is important in discerning true pathoanatomy that may require surgical repair. 41 A cordlike middle glenohumeral ligament with an associated sublabral foramen is an anatomic variant that does not require repair, as is an isolated sublabral foramen. A meniscoid labrum is another normal anatomic variant. Four anatomic variants of the biceps tendon origin have been described in relation to the superior labrum. Type I origin has been described as posterosuperior labrum, which was observed in 22%. Type II origin has been described as anterosuperior and posterosuperior labrum (primarily posterior), which was observed in 33%. Type III origin has been described as anterior and posterior labrum (equally), which was observed in 37%. Type IV origin has been described as superior labrum (primarily anterior), which was observed in 8%. 42 For functional characteristics, Type II superior labrum anterior and posterior (SLAP) tears can create statistically significant glenohumeral translations and an increased range of motion. 43 In this study, glenohumeral rotation and translation were measured before and after a type II SLAP tear simulation, as well as after arthroscopic repair of the lesion. Creation of a SLAP lesion resulted in significant increases in total range of motion, external rotation, internal rotation, anteroposterior translation, and inferior translation ( p < .05). However, translation and rotation were found to increase only slightly following the creation of a SLAP lesion. Arthroscopic repair using two suture anchors on either side of the biceps origin was found to restore glenohumeral stability approximately to the pretear state. 43


Pearls

SLAP tears (especially SLAP II tears) may be associated with increased instability and increased anterior translation of the glenohumeral joint.
The superior capsular ligaments (superior glenohumeral ligament [SGHL] and middle glenohumeral ligament [MGHL]) have large variability in attachment, configuration, and size.

Rotator interval
The rotator interval is a triangular space within the glenohumeral joint capsule (see Fig. 1-13 ). It is bordered by the coracoid at its base and by the supraspinatus and subscapularis muscles, which converge to an apex laterally. The coracoid separates the subscapularis from the supraspinatus medial to the glenohumeral joint. These muscles insert laterally, converging over the intertubercular sulcus. The rotator interval consists of the coracohumeral ligament (CHL) superficially and the SGHL in a deeper layer. The LHBT traverses this space intra-articularly from the supraglenoid tubercle, exiting the intertubercular groove distally. The area of the rotator interval triangle was reported to be significantly larger in males than in females, and the dimensions changed with rotation, becoming smaller with internal rotation. 44 It is recommended that rotator interval closure be performed with the arm externally rotated because imbricating the rotator interval with the arm internally rotated may lead to overtightening, with loss of external rotation. In addition, the medial aspect of the rotator interval was shown to control humeral head inferior translation in the adducted arm. 45 Clinically, a sulcus sign with an adducted externally rotated arm suggests rotator interval insufficiency. Rotator interval imbrication should be considered in a patient with multidirectional instability. However, this again should be considered with caution. Capsular plication and rotator interval closure have been shown to decrease translation in a simulated multidirectional instability model in cadaver shoulders, which was created by nondestructive capsular stretching. 46 This study showed that in shoulders with simulated multidirectional instability, the capsular plication alone reduces range of motion to the intact state. Reductions in translation, however, also may require the addition of rotator interval closure because the changes in translation and rotation after repair are dependent on arm position. In some positions, addition of rotator interval closure results in overtightening. Therefore, when treating multidirectional instability with arthroscopic capsular plication combined with rotator interval closure, a surgeon needs to evaluate the patients individually to determine whether the rotator interval closure is needed, so as to avoid overtightening. 46
The rotator interval is also important for LHBT stability. 45 , 47 , 48 The CHL, SGHL, supraspinatus, and subscapularis are laterally interdigitated, contributing to a sling that supports the LHBT within its groove. The CHL is attached proximally at the coracoid and fans out distally over the tuberosities, converging with the supraspinatus and subscapularis insertions. A deep layer of fibers from the CHL is primarily attached to the greater tuberosity, although a lesser component is attached to the lesser tuberosity, forming an anterior band that covers the LHBT. 45 The SGHL is attached proximally to the superior labrum and supraglenoid tubercle and is attached distally to the lesser tuberosity, forming an indissociable structure with the CHL. The CHL forms a roof over the LHBT, and the SGHL forms a floor; the anterior convergence of the CHL and SGHL forms a reflection pulley for the LHBT, which is also in contact with the subscapularis. 25 This anatomy is critical to appreciate with respect to “hidden” lesions where the LHBT subluxates or dislocates deep to the subscapularis, invisible from the bursal side. Werner et al 48 reported that the SGHL contributes to most of the fibrous sling that stabilizes the intra-articular portion of the LHBT.
The most distal aspect of the rotator interval has been described as a convergence and interdigitation of subscapularis and supraspinatus tendon fibers over the biceps tendon. 49 , 50 A recent study by Gleason et al 50 questioned the presence of a transverse humeral ligament at the area of this interdigitation. In this study, magnetic resonance imaging (MRI) analysis followed by gross and histologic examination revealed that tissue covering the bicipital groove formed a sling primarily of subscapularis tendon fibers, with less important contributions from the supraspinatus tendon and CHL. The subscapularis tendon fibers were found to divide and form a sling around the biceps tendon where it leaves the glenohumeral joint at the proximal part of the bicipital groove. This finding suggests that an isolated deep rupture of the subscapularis tendon can explain a hidden LHBT lesion and that a concomitant subscapularis tendon tear should be ruled out when an LHBT lesion is encountered.
Arthroscopic techniques have been developed to tension the rotator interval in patients with instability. Recent studies showed that external rotation can be significantly reduced with rotator interval imbrication. Specifically, Plausinis et al 51 reported that interval closure with the arm externally rotated 30 degrees significantly decreased flexion (mean, 6 degrees), external rotation (mean, 10 degrees), and anterior translation (mean, 3 mm) in the adducted shoulder. Gerber et al 52 also reported that anterosuperior capsular plication performed with the humerus in neutral rotation significantly decreased external rotation by 30 degrees with the arm adducted. Further study is required to understand the effect of rotator interval imbrication on specific pathoanatomies.
In an anatomic study to assess arthroscopic release of the rotator interval and CHL, 15 cadaveric specimens were dissected and studied. 53 The rotator interval was found to be 3 mm to 4 mm away from the coracoacromial ligament, with glenohumeral joint distention to 40 mm Hg. In addition, the coracoacromial ligament was shown to be a useful anatomic landmark for complete release of the CHL. Release from the supraspinatus to the subscapularis resulted in complete resection of the CHL. Intra-articular arthroscopic release of the rotator interval was found to safely and completely release the CHL if the dissection was taken superficially to the level of the coracoacromial ligament. Release of the CHL is particularly relevant during capsular release for adhesive capsulitis.
The anatomy of the rotator interval is complex. An increased understanding should lead to reliable and reproducible capsulorrhaphy techniques for patients with instability and help the surgeon appreciate hidden lesions and treat them appropriately. In addition, this area can be safely released arthroscopically in patients with adhesive capsulitis.


Pearls

The rotator interval is a complex area of anatomy, and comprises the coracohumeral ligament (CHL), superior and middle glenohumeral ligaments (SGHL, MGHL), the long head of the biceps (LHB), and a thin layer of capsule.
The CHL and associated lateral aspect of the subscapularis are important to maintain stability of the LHB in the bicipital groove.
The structures within the rotator interval may be injured in certain types of shoulder instability.

Active stabilizers
Soft tissue active stabilizers are muscle-tendon complexes that provide both function and stability to the shoulder. The active stabilizers include the tendons and the muscles of the rotator cuff, biceps, deltoid, pectoralis major, and the latissimus dorsi ( Fig. 1-18 ). The stabilizing effect of the shoulder muscles during active motion, leading in the subsequent limitation of the active arc of motion, has long been recognized. 54 The muscles provide stability to the shoulder by concavity compression and a barrier effect. 28 , 55 - 57 Specifically, the contribution of the active stabilizers was larger than the passive stabilizers, resulting in smaller displacements of the humeral head. 58 In another cadaveric study, the rotator cuff muscles and the capsule have been shown to have equal stabilizing functions in the anterior direction, but the cuff was found to have a more important stabilizing role in the posterior direction. 59 The activation of the rotator cuff muscles also results in rotation of the shoulder, producing a secondary tightening of the capsuloligamentous structure in the direction opposite the rotation. 54 , 60 , 61 It is also important to note that with their strong influence on shoulder stability, the muscles may contribute not only to stabilization of the joint but also to instability and dislocation of the joint. 62 - 64 Therefore, the muscle-tendon complexes provide both function and stability to the shoulder while simultaneously providing a large range of motion. The following sections describe the active soft tissue stabilizers for the shoulder with respect to specific anatomy.

FIGURE 1-18 The drawing shows the active stabilizers, which include the tendons and the muscles of the rotator cuff, biceps, deltoid, pectoralis major, and the latissimus dorsi.
(Redrawn and colorized; original drawing provided by Angie Lee.)

Rotator cuff
The rotator cuff consists of four muscles that surround and actively compress the humeral head into the glenoid socket. The subscapularis muscle originates on the anterior scapula and inserts into the lesser tuberosity of the proximal humerus. The supraspinatus originates within the fossa superior to the scapular spine, the infraspinatus originates from the fossa inferior to the scapular spine, and the teres minor originates from the dorsal surface of the axillary scapular border; these three muscles all insert into the greater tuberosity ( Fig. 1-19 ).

FIGURE 1-19 Each active muscle generates a force (F) whose direction is determined by the effective origin and insertion of that muscle. Note that the rotator cuff tendons wrap around the head of the humerus, so their effective point of attachment is on the humeral articular surface. Note also that each muscle force has a compressive (F c ) and a displacing (F d ) component. The product of the force multiplied by the radius (R) is the torque (F • R).
(Modified from Matsen FA, III, et al: Practical evaluation and management of the shoulder, Philadelphia, 1994, WB Saunders.)
The anatomy and histology of the posterior rotator interval have implications for release during rotator cuff repair. 65 The supraspinatus consists of a fusiform anterior muscle region that has a physiologic cross-sectional area approximately 2.5 times greater than that of the smaller posterior straplike muscle region; the tendon cross-sectional area is smaller anteriorly ( Fig. 1-20 ). This relationship suggests that the anterior supraspinatus encounters more stress than the posterior region. 66 This is further supported by a recent study by Gates et al 67 who reported that in the scapular plane, the anterior subregion of the supraspinatus acts as both an internal and external rotator, depending on the initial position of the humerus. The posterior subregion either acted as an external rotator or did not induce rotation. This study demonstrated a distinct functional difference between the anatomic subregions of the supraspinatus.

FIGURE 1-20 A, The supraspinatus muscle compresses the humeral head into the glenoid and thereby provides stability against displacement by the force of the deltoid (arrow). It is not optimally oriented to depress the head of the humerus because the inferiorly directed component of its force is small. B, Similarly, the subscapularis and infraspinatus compress the head into the glenoid, providing additional stability.
(From Matsen FA, III, et al: Practical evaluation and management of the shoulder, Philadelphia, 1994, WB Saunders.)
The insertional footprint of the rotator cuff has been the subject of recent attention. This footprint is the area to be restored during a surgical repair. Average maximum insertion lengths and widths were measured in 20 cadaveric specimens for the subscapularis (40 mm × 20 mm), supraspinatus (23 mm × 16 mm), infraspinatus (29 mm × 19 mm), and teres minor (29 mm × 21 mm). 68 In other studies, the anteroposterior dimension of the supraspinatus insertion averaged 22.5 mm (± 3.1 mm) or 25 mm. 69 The medial-to-lateral dimension of the insertion averaged 12.7 mm (± 6.3 mm) in one study 70 and 12.3 mm (± 0.4 mm) in another. 71 The variability in the dimensions largely depends on the size of the patient. The supraspinatus footprint ends posteriorly where the normal bare area begins, and it can provide an important landmark. The infraspinatus and teres minor insertions mark the lateral extent of the bare area 68 ( Fig. 1-21 ). The greater tuberosity has three facets (superior, middle, and inferior) upon which the rotator cuff inserts. The supraspinatus shares its footprint with the infraspinatus on the anterior aspect of the middle facet ( Fig. 1-22 ); therefore, repair of the supraspinatus may involve an obligatory repair of the infraspinatus. A “transosseous-equivalent” rotator cuff repair technique was shown to restore greater anatomic footprint contact and provide greater ultimate strength, compared with a double-row repair technique. 72 A follow-up study using a dynamic 30 degrees external rotation arc found a significantly higher yield strength for the transosseous-equivalent repair than for the double-row repair technique. 73

FIGURE 1-21 Compressive force from the infraspinatus and subscapularis can stabilize the humeral head in the absence of a supraspinatus, provided that the glenoid concavity is intact. A, Anteroposterior view. B, Axillary view.
(Modified from Matsen FA, III, et al: Practical evaluation and management of the shoulder, Philadelphia, 1994, WB Saunders.)

FIGURE 1-22 The supraspinatus sharing its footprint with the infraspinatus on the anterior aspect of the middle facet.
(Redrawn and colorized; original drawing provided by Angie Lee.)
The subscapularis internally rotates the humeral head in relation to the scapula, and the infraspinatus and teres minor externally rotate the proximal humerus. The primary function of the supraspinatus is to initiate the first 30 degrees of forward elevation and assist the deltoid in the first 90 degrees of abduction. The supraspinatus also plays a role in rotation; the center of rotation relative to the supraspinatus changes depending on the initial position of the humerus. With a starting position of neutral or external rotation, the supraspinatus externally rotates the humerus; in internal rotation, the supraspinatus internally rotates the humeral head. 74 , 75 Dynamic rotational effects on rotator cuff repair also have been investigated on a supraspinatus single-row repair, using two suture anchors and four simple suture configurations. 73 Based on electromyographic data, a relatively low load (60 N) for cyclic testing was used to simulate actual loads that may be encountered during postoperative exercises. 76 , 77 The anterior supraspinatus tendon was found to undergo significantly more strain and gap formation with external rotation (at yield strength, 1.95 mm [± 0.74 mm]) than with the humerus fixed (1.06 mm [± 0.54 mm], p = .0083). 73 The small gap formation confirms that a single-row repair can withstand the relatively low loads expected during rehabilitation after surgery. Approximately 2 mm of gap formation could represent one sixth (17%) of the footprint in the medial-lateral dimension, which may be significant. 70 , 71 The posterior tendon underwent negative strain (compression) with external rotation. For tested repairs allowing external rotation, gap formation and tendon strain were significantly greater in the anterior tendon than in the posterior tendon at both 30 degrees external rotation and yield load ( p < .05). No such differences appeared in the specimens tested with the humerus fixed. 73 Strain and gap formation differences should be considered as new repair constructs are developed to restore normal anatomy.

Long head of the biceps tendon
The LHBT originates on the supraglenoid tubercle and has an intimate association with the superior labrum ( Fig. 1-23 ). The LHBT exits the glenohumeral joint via the bicipital groove. The small head originates at the coracoid, and the muscle belly from each origin converges to form the biceps muscle proper. The insertion of the biceps is ultimately attached to the proximal radius on its tuberosity. Because the LHBT is associated with a muscle that acts across both the glenohumeral and ulnohumeral joints, it has been difficult to isolate its dynamic functional role in the shoulder.

FIGURE 1-23 The long head of the biceps tendon at extremes of humeral rotation.
(Redrawn and colorized; original drawing provided by Angie Lee.)
Six cadaveric shoulders were tested before and during biceps tendon release and after repair of a simulated type II SLAP tear. 78 The tear was created by release of the biceps anchor 8 mm anterior and 8 mm posterior to the biceps origin, with a 10 mm lateral-to-medial depth of release. Rotational and translational changes were recorded, as was the path of glenohumeral articulation at maximum internal rotation; 30°, 60°, and 90°; and maximum external rotation. Sequential loading of the LHBT with 0 N, 11 N, and 22 N revealed significant decreases in external rotation, internal rotation, and total range of motion with 22-N loading. Glenohumeral translation in the anterior, posterior, superior, and inferior directions was significantly decreased with 22-N loading. The humeral head shifted posteriorly with biceps loading at maximum internal rotation and 30 degrees and 60 degrees of external rotation ( p < .05). At maximum external rotation, biceps loading shifted the humeral head anterior and superior compared with unloaded shoulders ( p < .05). These findings support the belief that at least one functional role of the LHBT may be to act as a ligament to center the humeral head on the glenoid during the end ranges of rotational motion.

Humerothoracic muscles
Humerothoracic muscles are thought to contribute significantly to shoulder function and stability. This is based on the anatomy of these muscles where the deltoid in the superior direction and the pectoralis major and the latissimus dorsi in the inferior direction complete the force couple in superior-inferior direction. Specifically, the deltoid muscle is a large muscle, consisting of three major portions. An anterior portion originates from the lateral clavicle, a middle portion originates from the acromion, and a posterior portion originates from the spinous process of the scapula. 79 All three portions converge distally to insert on the deltoid tuberosity of the humerus. The anterior and posterior deltoid muscles have parallel fibers and the middle deltoid has multipennate fibers. The pectoralis major also consists of three portions. The upper portion takes origin from the medial half to two thirds of the clavicle 80 , 81 and inserts lateral to the bicipital groove. The middle portion takes origin from the sternum and ribs and inserts directly behind the clavicular portion maintaining a parallel fiber arrangement. The inferior portion takes origin from the distal body of the sternum, the fifth and sixth ribs, and the external oblique muscle fascia and inserts lateral to the bicipital groove. The latissimus dorsi muscle takes origin from the dorsal spine, a portion of the sacrum, and the iliac crest. It inserts into the bicipital or intertubercular groove. These large humerothoracic muscles around the shoulder have a strong influence on stability and function and therefore have been included in various biomechanical studies. 19 , 62 , 82

Coracoacromial arch anatomy

Coracoacromial ligament
The coracoacromial ligament bridges the anterolateral acromion and coracoid, creating an arch that helps contain the humeral head from excessive superior translation ( Fig. 1-24 ). The coracoacromial ligament has been described as quadrangular or Y shaped. 83 , 84 In most individuals, the coracoacromial ligament fans out from its acromial attachment to the coracoid in a V configuration. An accessory band is present in a few individuals. 83 - 85 A lateral extension of soft tissue from the coracoacromial ligament, termed the falx, blends with the conjoined tendon on the coracoid. 86 The coracoid process projects from the anterior scapular neck with variable inclination.

FIGURE 1-24 The drawing shows the coracoacromial arch anatomy. Note the coracoacromial ligament bridging the anterolateral acromion and coracoid, creating an arch that helps contain the humeral head from excessive superior translation.
(From Reider B, et al: Operative techniques, sports medicine surgery, Philadelphia, 2010, Saunders.)
Fealy et al 83 examined the coracoacromial ligament morphology with respect to acromial enthesopathy (spur formation). Nineteen dimensional parameters were defined for measurement. The most common anatomic structures of the coracoacromial ligament were an anterolateral band and a posteromedial band. The anterolateral band covered the entire anterior acromial undersurface; in 75% of the shoulders it extended to blend with the conjoined tendon, forming a coracoacromial falx. In 25%, there was no clear ligamentous differentiation. Spur formation was found to be correlated with a coracoacromial ligament that was relatively narrow, short, thick, and less divergent. Whether this morphology causes impingement or is a result of impingement could not be determined.

Acromioclavicular joint
The acromioclavicular joint is stabilized by the acromioclavicular joint capsule ligaments and conoid and trapezoid coracoclavicular ligaments ( Fig. 1-25 ). The conoid and trapezoid ligaments are attached from the distal clavicle inferiorly to the coracoid process superiorly. The acromioclavicular ligaments help stabilize anterior and posterior horizontal translations. The coracoclavicular ligaments prevent excessive superior translation across the acromioclavicular joint. The stability provided by each of these ligaments is believed to be critical in restoring the anatomy after a destabilizing acromioclavicular dislocation. The coracoclavicular ligaments provide vertical stability but not necessarily horizontal stability. 87 , 88 Recent reports describe anatomic reconstructions of both the acromioclavicular and coracoclavicular ligaments. 89 - 91

FIGURE 1-25 Drawing showing the acromioclavicular joint and stabilizing directions. A, Superior. B, Anterior.
(From Reider B, et al: Operative techniques, sports medicine surgery, Philadelphia, 2010, Saunders.)

Coracoid process
The coracoid process projects anteriorly and laterally from the scapular neck. It serves as a medial boundary to the subacromial space and rotator interval. Coracoid impingement against the subscapularis tendon and bursa can lead to anterior shoulder pain. Coracohumeral distance can be measured by examining axial shoulder images, usually on MRI; the measurement from the cortical margin of the coracoid to the cortical margin of the humeral head is approximately 3 mm to 11 mm. On average, a 5-mm measurement is associated with subscapularis tearing. The indications for performing coracoplasty are not clear; the patient’s history and physical examination must be consistent with the diagnosis of coracoid impingement. An arthroscopic intra-articular coracoplasty can be performed via the rotator interval. 92

Summary
The glenohumeral joint motion is a result of a complex interplay between the passive and active stabilizers that require intricate balance and synchronicity. The bony passive stabilizers include the glenoid, humeral head, and the proximal humerus. The soft tissue passive stabilizers include the glenoid labrum, glenohumeral ligaments, and the glenohumeral joint capsule. The active stabilizers include the tendons and the muscles of the rotator cuff, biceps, deltoid, pectoralis major, and the latissimus dorsi. It is important to note that the anatomy of these structures varies widely among patients. Appreciating this variability can allow the shoulder surgeon to adapt to individual pathoanatomy and help in restoring normal anatomy and function.

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CHAPTER 2 Examination and classification of instability

Brett D. Owens, MD, Travis C. Burns, MD, Thomas M. DeBerardino, MD

Key points

Shoulder instability is common, especially in young active adults.
Traumatic anterior events account for 80% of all instability and result in a predictable pattern of pathologic changes.
Thorough physical examination is imperative to include instability-specific tests such as apprehension, relocation, and load-shift.
Surgical stabilization is recommended for treatment of traumatic anterior shoulder instability in high demand patients.

Introduction
Glenohumeral instability is a commonly encountered problem in active populations, especially in young athletes. Our understanding of the anatomy and pathologic entities has evolved significantly since the initial descriptions of shoulder instability. As our knowledge has grown, so too has our armamentarium of procedures and therapies aimed at resolving the condition. A thorough history, clinical exam, appropriate radiologic studies, and a thorough characterization of each patient’s instability pattern will enable proper therapeutic interventions.

Definitions
The clinician must first discern instability from laxity. Laxity is a normal finding of asymptomatic glenohumeral translation, the degree of which may be affected by age, gender, fitness, and congenital factors. There is significant variability in the amount of shoulder translation in asymptomatic, normal subjects. On the other hand, instability is a pathologic process that results in excessive translation of the humeral head on the glenoid that results in pain, weakness, or performance degradation. Clinical instability is a disruption in the static restraints to glenohumeral motion, the osseous structures, capsule, labrum, and glenohumeral ligaments. Clinical instability is readily detected on translational assessment during routine physical exam maneuvers. A second category of instability is functional instability, a dynamic instability most common in overhead athletes. It is not readily detected on translational glenohumeral exam maneuvers and is commonly due to muscular imbalances, loss of proprioceptive control, and scapulothoracic dyskinesia. A thorough history and physical exam enable the clinician to discern between laxity and clinically significant instability.
It is also important to adequately define the terms used to describe instability. A glenohumeral dislocation event is a complete instability event in which no contact remains between the articular surfaces. This usually results in the humeral head coming to rest in the dislocated position, requiring a manual reduction by a trained provider. However, a spontaneous reduction is possible, especially in the case of glenoid or combined bone loss. The presence of a manual reduction maneuver in a patient’s history has often been used to ensure that a dislocation has occurred for research purposes. 1 , 2 The definition of an incomplete instability event has been elusive in the literature. Most clinicians use the term “subluxation” to refer to all events that fall short of being complete events (dislocations), and that is the definition preferred by the authors. However, a subluxation event should not be confused with a microinstability event, which is a microtraumatic overuse-type injury mostly seen in throwing athletes.


Pearls

A glenohumeral dislocation event is defined by complete dissociation of articular surfaces and usually requires a manual reduction maneuver.
A subluxation event can encompass a wide spectrum of symptomatic translation, including near-dislocation events.


Pitfalls

Do not confuse asymptomatic glenohumeral laxity (which can be common in young women and certain athletes) with instability: always examine the contralateral side.
Laxity is a normal finding of the glenohumeral joint and allows for the complex motion of the shoulder. Instability is pathologic laxity usually caused by an instability event.
Ligamentously lax individuals do not always have multidirectional instability; they also may have sustained a traumatic event ( Fig. 2-1 ). History is important.

FIGURE 2-1 Venn diagram showing that traditional dichotomy between TUBS and AMBRI patients do have potential for crossover. For example, a ligamentously lax female can sustain a traumatic anterior glenohumeral dislocation while playing rugby and may not fit cleanly into either category.

Classification historical background
Among the earliest means of differentiating shoulder instability was direction, with most dislocations being anterior. In 1952, McLaughlin reported on patients with posterior events and found them to comprise only 4% of all dislocations. 3 This breakdown by directionality has held true over time, with a recent prospective cohort study showing 5% of dislocations in young athletes were posterior in direction. 4 However, while complete instability events (dislocations) in the posterior direction are rare, posterior subluxation events are more common, comprising 11% of all subluxation events. 4
The most commonly used dichotomy of instability events (both dislocation and subluxation) is related to mechanism of injury. Rowe was the first to use traumatic versus atraumatic mechanisms to classify dislocations and found a higher recurrence rate in atraumatic patients. 5 Rockwood classified subluxations into traumatic and atraumatic injuries as well as separate voluntary instability patients, 6 and showed good results with nonsurgical management of atraumatic and voluntary patients. 7 Thomas and Matsen continued this theme and produced the most useful classification system to date: AMBRI and TUBS ( Table 2-1 ). 8 The authors separated shoulder instability into two broad categories, the first of which was made up of patients with A traumatic, M ultidirectional, B ilateral involvement, and who were treated initially with R ehabilitation or I nferior capsular shift. The second broad category included patients with a T raumatic dislocation, U nilateral direction, and who had commonly sustained a B ankart lesion requiring S urgery (TUBS). These two descriptors accurately describe both ends of the instability spectrum but do not address the gradations between.
Table 2-1 Thomas and Matsen Classification of Instability T – Trauma A – Atraumatic U – Unidirectional M – Multidirectional B – Bankart B – Bilateral S – Surgery R – Rehabilitation   I – Inferior (capsule)
Gerber and Nyffeler parted from previous authors division of shoulder instability based on direction or mechanism and proposed a classification scheme based on static and dynamic shoulder instabilities. 9 The authors identified three separate groups of instability: static, dynamic, and voluntary. The static group is subdivided by directionality and the dynamic group is subdivided based on the presence or absence of ligamentous laxity. Patients with voluntary instability comprised the third category.

Algorithmic approach
Because of the multitude of etiologies, mechanisms, directions, and contributing factors to glenohumeral instability, no encompassing classification scheme accurately accounted for patients’ unique instability. As a result, several authors have gone to a logarithmic or descriptive approach of shoulder instability. 10 , 11 The variables in the algorithmic tree are acuity, direction, presence of trauma, degree of instability, and volitional control of the instability episodes. The algorithmic approach assists the surgeon in assessing the important variables in the patient’s condition, which identifies the presumed pathologic lesion and therapy.
The four variables from the patient history that are commonly linked to the shoulder pathology and subsequent treatment are direction of instability, etiology, frequency, and degree. These four elements of shoulder instability are not independent variables, but describing each characteristic of a patient’s condition allows for the most accurate and precise description. Many algorithmic approaches fail in rare circumstances, such as a patient with a traumatic Bankart and unilateral findings of an inferior sulcus sign associated with multidirectional instability. 10
While many algorithmic approaches encompass the entire spectrum of glenohumeral instability, we offer a simplified algorithm that focuses on traumatic anterior instability that represents 80% of instability that occurs. 4 We also have attempted to provide general treatment recommendations (surgery vs. rehabilitation) based on the characteristics of the instability ( Fig. 2-2 ).

FIGURE 2-2 This figure is the authors’ proposed treatment algorithm for traumatic anterior instability, which comprises 80% of instability events. MDI, multidirectional instability; MRI, magnetic resonance imaging.

Physical exam
Although a patient’s history may guide the examiner to focus on specific aspects of the physical exam, a generalized upper examination is important to avoid missing contributing pathology that was misrepresented or omitted from the history. The physical exam of shoulder instability follows the same routine of thorough musculoskeletal exams with inspection, palpation, range of motion assessment, testing of motor strength, neurovascular examination, and specialized tests for shoulder instability. Examination of the shoulder should be preceded by an examination of the neck and cervical spine. The patient should have both shoulders completely exposed, and the examination should begin at each phase with the asymptomatic shoulder.

Inspection
During inspection of the shoulder girdle, muscular contour should be evaluated for asymmetry indicative of muscular atrophy of the deltoid, supraspinatus, or infraspinatus muscles. Squaring of the lateral shoulder border with a prominent acromion may represent deltoid atrophy from an axillary nerve injury ( Fig. 2-3 ). Atrophy of the supraspinatus above the scapular spine may represent a large rotator cuff tear or suprascapular nerve entrapment at the suprascapular notch. Atrophy of the infraspinatus below the scapular spine may likewise represent a massive rotator cuff tear in an older patient or could indicate suprascapular nerve entrapment at the spinoglenoid notch in a throwing athlete, commonly from a ganglion cyst.

FIGURE 2-3 This clinical photograph shows a 23-year-old patient 3 months after sustaining traumatic glenohumeral dislocation from a motorcycle accident. This photograph shows deltoid atrophy from an axillary nerve palsy. The patient also sustained a bony Bankart lesion and displaced lesser tuberosity fracture repaired through an open anterior approach.
The position of the glenohumeral joint can be assessed by the position of the humeral head relative to the acromion. In a posterior dislocation, the humeral head may be prominent posteriorly, and the lateral acromion may be prominent in an inferior subluxation. The scapular body position also should be assessed for scapular winging. Finally, the skin should be inspected around the shoulder for evidence of previous surgical incisions, thin atrophic skin, or excessive scar widening that may indicate a collagen disorder.

Palpation
Palpation of the shoulder girdle for warmth, pain, and crepitus is important and should include assessment of the coracoid, biceps tendon, acromioclavicular joint, and Codman point. Codman point, anterior to anterolateral corner of acromion with the patient’s hand on their buttocks, classically is a site of tenderness for supraspinatus or infraspinatus tendon pathology and impingement syndrome. In the setting of instability, tenderness over the greater tuberosity also may indicate a tuberosity fracture after dislocation or secondary impingement due to microinstability. Palpation of the acromioclavicular joint and the acromion could indicate acromioclavicular synovitis or a symptomatic os acromiale. Palpation circumferentially inferior to the acromion border also will confirm the position of the humeral head relative to the glenoid. A hollow sulcus is often palpable inferior to the lateral border of the acromion after an anterior glenohumeral dislocation. Patients often have posterior capsule tenderness even after reduction of an anterior dislocation. This portion of the exam should conclude with palpation around the circumference of the scapula. Patients with multidirectional instability may complain of pain diffusely around the scapula. Finally, palpation of the quadrilateral space should be performed for compression of the axillary nerve.

Range of motion
After recording sites of tenderness, the shoulder is taken through a full active range of motion. We record maximum active forward flexion, internal rotation in adduction and 90 degrees of abduction, and external rotation in adduction and 90 degrees of abduction. Internal rotation in adduction is recorded relative to the nearest vertebral level. Although variable in patients, anatomic landmarks, such as the medial edge of the scapular spine corresponds to T3, the inferior scapular border to T7, the most inferior rib to T12, and the L4 spinous process to the superior edge of the iliac crests, are useful for estimating internal rotation. Commonly, overhead athletes have an increased ability to externally rotate their dominant extremity, but they have a concomitant loss of internal rotation, leaving the total arc of motion symmetric to the contralateral extremity. Glenohumeral internal rotation deficit (GIRD) may exist if the total arc of motion is greater than 25 degrees less than the contralateral shoulder and may predispose the patient to internal impingement or labral pathology.
If a patient has a deficit in active motion, the examiner should determine if the patient has full passive motion. Importantly, patients with a locked posterior shoulder dislocation have a loss of external rotation actively and passively on the affected side. Large rotator cuff tears may manifest initially with a loss of active external rotation while maintaining full passive motion. Monitor forward flexion and abduction from behind the patient to observe for scapular asymmetry or winging during motion. Medial and lateral scapular winging may be attributable to long thoracic or cranial nerve XI palsies, but they also may be due to scapular dyskinesis in throwing athletes and patients with multidirectional instability.

Muscular strength testing
While partially examining motor strength during active motion testing, it is important to record generalized muscle strength for shoulder abduction, elbow flexion and extension, wrist flexion and extension, and hand intrinsic muscles. Although muscle strength grading is imperfect because the exam is subjective in nature and it only measures static muscle strength, it is important to record for a baseline reference. Comparison to the contralateral extremity is most important, and although it is rarely used in routine clinical examination, handheld dynamometry can be used to more accurately quantify muscle strength.
The rotator cuff muscles also should be assessed specifically for strength. Jobe’s empty can test isolates the supraspinatus muscle ( Fig. 2-4 ). The test is performed with the arm flexed to 90 degrees in the scapular plane, thumb pointed down, while the examiner applies a downward force. Pain or weakness resisting the downward pressure indicates pathology in the supraspinatus muscle. The “full can” test also can isolate the supraspinatus with the thumb pointed up, which may be less painful in patients with impingement.

FIGURE 2-4 A, This clinical photograph shows “empty can” testing to evaluate supraspinatus strength. The arms are flexed to 90 degrees within the plane of the scapula, and the forearms are maximally pronated. Appreciable weakness suggests tearing of the supraspinatus tendon. B, Again, the supraspinatus is tested by positioning the arm in 90 degrees of abduction in the plane of the scapula and in slight internal rotation. This puts the supraspinatus tendon on top of the humeral head. The patient holds this position while the examiner attempts to adduct the arm.
(Redrawn from Matsen FA, III, et al: Principles and procedures, Philadelphia, 2004, WB Saunders, p 286.)
Resisted external rotation at the side and in 90 degrees of abduction tests the strength of the posterior rotator cuff ( Fig. 2-5 ). An inability to hold the arm in full external rotation position passively is a positive lag sign and indicative of a large posterior rotator cuff deficit. The “hornblower” sign was first described in obstetric brachial plexus palsies, indicating the difficulty to get a hand to the mouth without the ability to externally rotate the shoulder. The hornblower sign is an external rotation lag with the arm in 90 degrees of abduction, and the drop sign is a lag sign with the arm at the side. The hornblower sign was reported to be 100% sensitive and 93% specific for degeneration of the teres minor, and the drop sign to be 100% sensitive and 100% specific for degeneration of the infraspinatus.

FIGURE 2-5 This clinical photograph manifests external rotation strength testing to evaluate the posterior rotator cuff.
Finally, independent assessment of subscapularis function should be performed with the lift off, belly press, belly off, and bear hug tests. The lift off test is performed with the hand on the lumbar spine, and the patient lifts the hand off of the back ( Fig. 2-6 ). The test also can be performed as a lag test by passively lifting the hand off the back and asking the patient to hold the position. An inability to hold the position may suggest subscapularis dysfunction. The examination may be difficult in shoulder conditions with pain in internal rotation preventing the patient from comfortably placing their hand on their lumbar spine. Also, a false negative test may result from the patient using the triceps muscle to move the hand away from the back. The belly press test was described for those patients unable to perform the lift off test as a result of internal rotation contracture. It is performed with the hand on the abdomen with the wrists in neutral position and the elbows in the plane of the body. With the subscapularis intact, the patient can apply pressure to their abdomen with internal rotation of the shoulder. Patients with subscapularis dysfunction are unable to internally rotate, and they flex the wrist or move the elbow posteriorly to press on the abdomen. The belly off test is similarly performed with the affected arm passively held at the elbow in slight flexion and internal rotation. The examiners other hand passively places the patients hand on the abdomen. The examiner instructs the patient to hold the maximally internally rotated position and releases the hand. If the hand rises off the patient’s abdomen when released, it is considered a positive test for subscapularis dysfunction.

FIGURE 2-6 A, B, and C, The subscapularis is tested by having the patient press the hand in toward the stomach. D, E, and F, Gerber lift-off test to evaluate subscapularis strength. The subscapularis also may be tested by having the patient push the hand away from the lumbar area posteriorly.
(Photographs courtesy of Robert A. Arciero, MD, and Augustus D. Mazzocca, MD; Illustrations redrawn from Matsen FA, III, et al: Principles and procedures, Philadelphia, 2004, WB Saunders, p 287.)
The bear hug test is performed with the arm in 90 degrees of forward flexion, the elbow flexed and held as far anterior to the body as possible, and the hand placed on the contralateral shoulder. The examiner attempts to lift the hand off of the shoulder while the patient resists ( Fig. 2-7 ). An electromyogram (EMG) evaluation study revealed increased upper subscapularis activation with the bell press test and increased lower subscapularis activation with the lift off test. 12 The bear hug test is reportedly the examination maneuver to better assess superior subscapularis function after the previous EMG study noted the increase in superior subscapularis activation as the arm moved from the extended position to the flexed position.

FIGURE 2-7 This clinical photograph shows the “bear hug” test to evaluate subscapularis strength.

Neurovascular exam
Neurologic injuries are common after a shoulder dislocation or subluxation, and it is important to document the initial neurologic examination. The axillary nerve can be assessed by assessing sensation over the region of the lateral shoulder. Axillary nerve motor examination can be tested by resisted shoulder abduction (deltoid) and external rotation (teres minor). While axillary nerve injury is the most common nerve injury after a shoulder dislocation or subluxation, a neurologic exam of the median, ulnar, radial, and musculocutaneous nerves also should be documented.
The Spurling test may assist in determining the contribution of cervical compression contributing to shoulder pain. The neck is flexed and rotated to each side with axial compression applied by the examiner. A positive test for cervical nerve compression is reproduction of radicular neck pain extending into an extremity.
The vascular exam should begin with simple inspection of the extremity to note pallor, trophic skin changes, venous engorgement, or hair loss. Palpation of the radial and ulnar pulses and observation of capillary refill should be compared to the contralateral extremity.
Thoracic outlet syndrome should be evaluated in any patient with vague upper extremity pain and weakness. Although the sensitivity and specificity of the individual physical exam findings have been low, their addition to a comprehensive shoulder exam may assist with arriving at the proper diagnosis. Most commonly used is the Adson maneuver in which the patient’s neck is extended, shoulders are extended, the patient holds a deep breath, the arm is extended and slightly abducted, and the chin is turned to the ipsilateral shoulder to tether the brachial plexus with the anterior and middle scalene muscles. The position is held for 15 to 30 seconds while the radial pulse is monitored for reproduction of symptoms or obliteration of the pulse. Positive exams have been reported in the literature with side bending toward the affected side and away from the affected side.
The hyperabduction position has been described to diminish the pulse in asymptomatic shoulders. It is more important to note tenderness in the supraclavicular region or pain with thumb pressure in the supraclavicular region over the brachial plexus. The Roos test is performed with both shoulders in 90 degrees of abduction and external rotation with the elbow flexed to 90 degrees, and the patient is instructed to repetitively open and close each fist for 3 minutes. A positive test result is reproduction of symptoms. The difficulty in this maneuver is the starting position is the apprehension position, which will be uncomfortable for patients with anterior glenohumeral instability.

Anterior instability
The apprehension test is performed with the patient sitting or supine with the edge of the bed supporting the scapula. 13 The arm is placed in 90 degrees of abduction and the elbow flexed and held by the examiner’s right hand for a right shoulder exam ( Fig. 2-8 ). The arm is externally rotated, and an anteriorly directed force is applied with the examiner’s left thumb applied to the posterior aspect of the humeral head. Pain or apprehension with the maneuver is associated with an injury to the anterior labrum. The augmentation test can be applied if you suspect anterior instability, but the patient has an equivocal response to the apprehension test. The augmentation test is performed in the same position of apprehension, abduction and maximum external rotation, and the examiner places an anteriorly directed force on the proximal humerus ( Fig. 2-9 ). The relocation test is performed with the patient in the same position on the examination table. 14 With the arm in the position of apprehension, a posteriorly directed force is applied to the proximal humerus, and a relief of the apprehension or pain is a positive test result ( Fig. 2-10 ). Relief of shoulder pain with the relocation test also has been associated with superior labrum anterior and posterior (SLAP) lesions. The release test (or surprise test) is performed after the relocation test by removing the posteriorly directed force on the proximal humerus. 10 A positive test result is return of pain and apprehension in the shoulder.

FIGURE 2-8 A and B, These clinical photographs show the performance of the anterior apprehension test. An examination is positive when the patient expresses “apprehension” or the feeling of their shoulder slipping out of socket when in this abducted externally rotated position.
(Photo B provided courtesy of Robert A. Arciero, MD, and Augustus D. Mazzocca, MD.)

FIGURE 2-9 This clinical photograph shows the performance of the anterior augmentation test. The addition of an anteriorly directed force to the posterior aspect of the proximal arm may result in an increase in the apprehension experienced by the patient with instability.

FIGURE 2-10 This clinical photograph shows the performance of the anterior relocation test. The addition of a posteriorly directed force to the anterior proximal arm results in relief of patient apprehension in the abducted, externally rotated position.
(Provided courtesy of Robert A. Arciero, MD, and Augustus D. Mazzocca, MD.)
The load-and-shift test is our preferred test to determine passive translation of the humeral head on the glenoid. The test can be performed sitting or supine, but the supine position provides the examiner scapular stabilization against the examination table to isolate glenohumeral motion. The arm is abducted 20 degrees and held in slight flexion in the plane of the scapula. While examining a right shoulder, the examiner grasps the patient’s forearm with their right hand and applies a compressive force to center the humeral head on the glenoid. The examiner grasps the proximal humerus with the left thumb and index finger around the humeral head and applies an anterior directed force ( Fig. 2-11 ). The direction of force should then be applied posteriorly and inferiorly. The grading of the load-and-shift translation tests is classified by the modified Hawkin’s grade, based on the amount of humeral head translation: grade I—minimal translation along the glenoid fossa, grade II—translation to the glenoid rim, and grade III—translation over the rim ( Fig. 2-12 ).

FIGURE 2-11 A and B , These clinical photographs show the performance of the anterior load-shift examination. The examiner loads the humerus longitudinally into the glenoid socket and attempts to translate the humeral head over the glenoid rim in the anterior direction. This test also may be performed in the posterior and inferior directions. C , Glenoidogram. The glenoidogram is the path taken by the center of the humeral head as it translates across the face of the glenoid in a specified direction away from the glenoid center line. The height of the glenoidogram reflects the amount of work needed to dislocate the humeral head for a given compressive load.
( A and B provided courtesy of Robert A. Arciero, MD, and Augustus D. Mazzocca, MD. C from Matsen FA, III, et al: Shoulder surgery: Principles and procedures, Philadelphia, 2004, WB Saunders, p 100.)

FIGURE 2-12 Load-and-shift test. The adequacy of the glenoid concavity in a given direction can be assessed by compressing the humeral head into the glenoid concavity and noting the amount of displacing force necessary to translate the head. A shows a normal concavity and B shows a diminished concavity in the direction of texting.
(From Matsen FA, III, et al: Shoulder surgery: Principles and procedures, Philadelphia, 2004, WB Saunders, p 113.)
The Gagey hyperabduction test assesses the integrity of the inferior glenohumeral ligament. 15 The test is performed with the patient sitting and the examiner positioned behind the patient ( Fig. 2-13 ). The elbow is positioned at 90 degrees and the arm is in neutral rotation. With one hand pushing down on the shoulder girdle, the other hand of the examiner lifts the relaxed upper extremity. Passive abduction greater than 105 degrees indicates laxity of the inferior glenohumeral ligament ( Fig. 2-14 ). In the initial description of the maneuver, 85% of patients with shoulder instability had passive abduction greater than 105 degrees, while the remaining patient’s abduction was limited by apprehension and pain.

FIGURE 2-13 Clinical photograph manifesting a positive Gagey sign with glenohumeral abduction beyond 110 degrees.

FIGURE 2-14 Reproduction of the effects of the Gagey test on the ligamentous structures of the glenohumeral joint. A, The glenohumeral joint is in full adduction and the glenohumeral joint capsule and ligaments are relaxed. B, The humerus is in full abduction and the capsule becomes taught; the inferior glenohumeral ligament (IGHL) limits the abduction to 90 degrees. C, The anterior band of the IGHL is most taught in full abduction.

Posterior instability
Posterior load-and-shift test is performed with the patient’s arm placed in the plane of the scapula, abducted to 45 degrees, and placed in 45 to 60 degrees of external rotation. The load-shift maneuver is then performed in similar fashion with the examiner behind the patient if performed sitting, or standing to the side of the patient if performed supine. The examiner’s hand away from the patient functions to apply a centering compressive force to the extremity and to control different angles of rotation. The hand closest to the patient applies a posteriorly directed force on the proximal humerus. The arm is moved into progressive internal rotation, which should increase the tension of the posterior capsuloligamentous structures and decrease translation. The scoring system is the same as above and should always be compared to the contralateral shoulder. Up to 50% displacement of the humeral head may be considered normal, but should always be compared to the contralateral shoulder for asymmetric increases in translation.
The posterior stress test (or posterior apprehension) is performed with the patient in the supine position, the arm is forward flexed to 90 degrees and maximally internally rotated. 10 The examiner places a posteriorly directed force through the elbow with the other hand posterior to the shoulder to palpate a subluxation of the humeral head ( Fig. 2-15 ). The test is positive with palpable subluxation or dislocation, apprehension of a pending dislocation, or pain that reproduces the patient’s symptoms.

FIGURE 2-15 A and B, These clinical photographs show the performance of the posterior apprehension test. The arm is forward flexed to 90 degrees and adducted. A posteriorly directed force is applied to the arm and the sensation of posterior instability results in a positive sign. C, Positive jerk test: The humeral head of the axially loaded arm slides out the back of the shoulder when the arm is adducted across the body and clunks back in when the arm position is aligned with the scapula.
( A and B provided courtesy of Robert A. Arciero, MD, and Augustus D. Mazzocca, MD.) ( C is redrawn from Matsen FA, III, et al: Shoulder surgery: Principles and procedures, Philadelphia, 2004, WB Saunders, p 115.)
The Jahnke or jerk test is performed with the patient sitting on the examination table. The patient’s arm is forward flexed to 90 degrees and placed in maximal adduction and internal rotation. The examiner applies a posterior directed force through the elbow. The arm is dislocated or subluxated in this position in patients with posterior instability. While maintaining the posteriorly directed force, the examiner slowly takes the arm out of adduction and a “clunk” or “jerk” is appreciated as the humeral head reduces into the glenoid.

Inferior and multidirectional instability
The sulcus sign is elicited with the patient seated and the arms relaxed by his or her side. With the arm in neutral rotation, the examiner places a downward distraction force on the distal humerus while monitoring the lateral acromial edge ( Fig. 2-16 ). Inferior instability will allow for a sulcus to be formed inferior to the lateral acromion, which can be measured in centimeters. The test is then performed in maximum external rotation, which places the anterior capsule and rotator interval under tension. If the sulcus sign persists in external rotation, it is indicative of rotator interval incompetence.

FIGURE 2-16 This clinical photograph shows the performance of the sulcus sign. With the arm hanging at the patient’s side, an inferiorly directed force is applied to the forearm or elbow, and the dimpling of the deltoid just inferior to the acromial border suggests inferior translation of the humeral head on the glenoid fossa (black arrow).
Patients with multidirectional instability can have any of the physical exam findings discussed previously, and many patients have signs of ligamentous laxity in multiple joints, including their contralateral shoulder. A Beighton score can be used to objectively assess generalized articular mobility. 16 It is a scoring system from 0 to 9 with a score greater than 3 or 4 in a skeletally mature adult being associated with generalized hypermobility. One point is assigned for the patient’s ability to do each of the following maneuvers: small finger metacarpophalangeal hyperextension beyond 90 degrees for left and/or right finger, ability to touch left and/or right thumb on volar forearm, hyperextension of left and/or right elbow greater than 10 degrees, hyperextension of left and/or right knees beyond 10 degrees, and ability to place palms of hands flat on the floor with knees fully extended ( Table 2-2 ). A score of 4 or more is associated with a diagnosis of generalized ligamentous laxity; however, a score of 2 or more also has been associated with a history of glenohumeral instability. 17
Table 2-2 Modified Beighton Scale Items and Criteria for a Positive Sign Beighton Scale Items N Criteria for Positive Sign * Passive hyperextension of the small finger 2 >90 degrees Passive thumb to forearm 2 Thumb touches forearm Elbow hyperextension 2 >10 degrees Knee hyperextension 2 >10 degrees Standing trunk flexion with knees locked in extension 1 Both palms flat on floor
* The score is compiled from a total of 9 possible positive tests and is expressed as X of 9.
Modified from Cameron KL et al: Association of generalized joint hypermobility with a history of glenohumeral joint instability. J Athl Trng 45(3): 253-258, 2010.

Biceps and slap
Superior labral detachment can be associated with glenohumeral instability, is often associated with other intra-articular pathology, and should likewise be evaluated in a comprehensive shoulder evaluation. O’Brien described the active compression test to evaluate the superior labrum. Standing behind the patient, the patient forward flexes the arm to 90 degrees, adducts the arm 15 degrees across their body, and maximally internally rotates his shoulder to point his thumb to the floor. 18 The patient resists a downward force applied by the examiner and notes the location of pain ( Fig. 2-17 ). The patient then repeats the examination in maximal supination. Relief of “deep” pain inside the shoulder with the palm up indicates a positive test for superior labral pathology. Pain on “top” of the shoulder likely represents acromioclavicular joint pathology or impingement syndrome. Also utilizing traction on the biceps insertion, the SLAPprehension test is performed with cross chest adduction of the affected shoulder with the elbow extended and forearm pronated. A positive test occurs with pain in the bicipital groove, an audible or palpable click, or apprehension. The crank test is performed with the arm elevated to 160 degrees in the scapular plane, axial compression is applied by the examiner, and the shoulder is passively rotated through full internal and external rotation. This examination is of uncertain utility in patients with prior glenohumeral dislocations as the examination is similar to the apprehension position and this patient group was excluded from the initial report on the maneuver. The anterior slide test is performed with the patient’s hands on the hips and the thumbs posteriorly positioned; the examiner stands behind the patient and places one hand on the superior shoulder and the other hand on the patient’s elbow. The examiner places a slightly anterior and superior force on the shoulder to load the biceps anchor. 19 A positive test result is pain in the anterior shoulder, a palpable click in the anterior shoulder region, or a reproduction of the symptoms that occurred with overhead activities. Patients with SLAP tears also may have pain with classic biceps provocation maneuvers like Speed’s and Yergason’s tests. Speed’s test is performed by having the patient forward flex the arm with the elbow at 30 degrees of flexion and the forearm supinated. Yergason’s test is performed by having the patient perform resisted supination with the elbow flexed to 90 degrees. A positive test for each exam is pain in the bicipital groove.

FIGURE 2-17 This clinical photograph shows the performance of O’Brien’s active compression test. The arm is forward flexed to 90 degrees and adducted 10 degrees with the forearm maximally pronated. The examiner applies an inferiorly directed force to the arm while the patient resists. A positive test is manifested by the patient experiencing pain with this maneuver.

Diagnostic injections
Diagnostic injections are beneficial in the office setting to differentiate sources of pain and to predict response to surgical intervention. The impingement test is performed by injecting local anesthetic into the subacromial space, and repeating the clinical exams for impingement. Improvements in pain after injection suggests subacromial pathology. The percent improvement in patient’s symptoms is documented before leaving the clinic. If pain relief is incomplete with a subacromial injection, an intra-articular injection of lidocaine is performed. Pain relief in the bicipital groove or improvement in pain with biceps provocation maneuvers is suggestive of detachment of the biceps insertion or biceps tendonitis. Persistent pain after intra-articular injection associated with bicipital groove pain may be associated with significant inflammation in the tendon sheath preventing infiltration of local anesthetic. A direct injection into the tendon sheath may be attempted, but ultrasound guidance may be necessary to ensure sheath penetration and avoid tendon infiltration. Persistent superior shoulder pain around the acromioclavicular joint may be assessed with an intra-articular acromioclavicular joint injection.
Finally, suspected suprascapular nerve entrapment can be assessed with pain relief after a suprascapular notch injection.

Examination under anesthesia
An examination under anesthesia is required before any operative procedure and may be necessary in some situations to indicate a patient for surgical management. Pain and apprehension from glenohumeral translation may cause muscle contraction to prevent joint translation. Anesthesia removes voluntary and involuntary guarding of the upper extremity to allow the examiner to more accurately assess the glenohumeral ligaments and capsule.
Cofield described a sequential examination of the shoulder in an anesthetized patient. The examination is based on a series of translations similar to the load-and-shift exam that yielded a 100% sensitivity and 93% specificity in the authors’ hands. 20 Examining the right shoulder with the patient supine, the examiner stands beside the patient and grasps the forearm with their right hand. The left hand is placed across the superolateral shoulder with the index and middle fingers placed over the anterior humeral head and the thumb over the posterior humeral head. While the right hand positions the arm in 20 to 30 degrees of abduction, the humeral head is translated in each of five directions: anterior, anterior-inferior, posterior, posterior-inferior, and inferior. The translations performed anteriorly (anterior and anterior-inferior) are performed in neutral rotation, 40 degrees of external rotation, and 80 degrees of external rotation. The translations performed posteriorly (posterior and posterior-inferior) are performed in neutral rotation, 40 degrees of internal rotation, and 80 degrees of internal rotation. The results from the injured extremity are compared to the contralateral shoulder, and a difference of two grades is considered significant.


Pearls

Patients present with a wide spectrum of physiologic laxity; it is essential to compare the instability exam findings to the contralateral (asymptomatic) side for comparison and for differentiating the reproduction of symptoms during provocative testing.
Young athletes with intra-articular shoulder complaints (which may even include pain) have instability (especially posterior instability) until proven otherwise.
The number one complaint in patients with posterior instability is pain.


Pitfalls

Accurate neurologic and rotator cuff examination is essential to document in both the young and older patient with a history of glenohumeral dislocation, given the high incidence of these lesions.
It can be helpful to document the suspected direction of instability based on a patient’s history and examination because arthroscopy may reveal no distinct pathology or labral tears both anteriorly and posteriorly. Understanding the patient’s symptomatic movements may help guide surgical treatment and/or rehabilitation.

Summary
Glenohumeral instability is a common injury. A careful physical examination is imperative to help guide appropriate diagnosis and treatment. Traumatic anterior events result in a high rate of pathology and should be treated with surgical stabilization in high demand patients.
The views expressed in this chapter are those of the authors and do not reflect the official policy or position of the Department of the Army, Department of Defense, or the United States Government.

References

1. Arciero RA, et al. Arthroscopic Bankart repair versus nonoperative treatment for acute, initial anterior shoulder dislocations. Am J Sports Med . 1994;22(5):589-594.
2. Hovelius L, et al. Recurrences after initial dislocation of the shoulder. Results of a prospective study of treatment. J Bone Joint Surg Am . 1983;65(3):343-349.
3. McLaughlin H. Posterior dislocation of the shoulder. J Bone Joint Surg Am . 1952;24-A-3:584-590.
4. Owens BD, et al. The incidence and characteristics of shoulder instability at the United States Military Academy. Am J Sports Med . 2007;35(7):1168-1173.
5. Rowe CR. Prognosis in dislocations of the shoulder. J Bone Joint Surg Am . 1956;38-A(5):957-977.
6. Rockwood CAJr. Subluxation of the shoulder—the classification, diagnosis, and treatment. Orthop Trans . 1979;3:306.
7. Burkhead WZJr, et al. Treatment of instability of the shoulder with an exercise program. J Bone Joint Surg Am . 1992;74(6):890-896.
8. Thomas SC, et al. An approach to the repair of avulsion of the glenohumeral ligaments in the management of traumatic anterior glenohumeral instability. J Bone Joint Surg Am . 1989;71(4):506-513.
9. Gerber C, et al. Classification of glenohumeral joint instability. Clin Orthop Relat Res . 2002;400:65-76.
10. Silliman JF, et al. Classification and physical diagnosis of instability of the shoulder. Clin Orthop Relat Res . 1993;291:7-19.
11. Pollock RG, et al. Recurrent posterior shoulder instability. Diagnosis and treatment. Clin Orthop Relat Res . 1993;291:85-96.
12. Tokish JM, et al. The belly-press test for the physical examination of the subscapularis muscle: Electromyographic validation and comparison to the lift-off test. J Shoulder Elbow Surg . 2003;12(5):427-430.
13. Rowe CR, et al. Recurrent transient subluxation of the shoulder. J Bone Joint Surg Am . 1981;63(6):863-872.
14. Jobe FW, et al. Shoulder pain in the overhand or throwing athlete. The relationship of anterior instability and rotator cuff impingement. Orthop Rev . 1989;18(9):963-975.
15. Gagey OJ, et al. The hyperabduction test. J Bone Joint Surg Br . 2001;83(1):69-74.
16. Beighton P, et al. Articular mobility in an African population. Ann Rheum Dis . 1973;32(5):413-418.
17. Cameron KL, et al. Association of generalized joint hypermobility with a history of glenohumeral joint instability. J Athl Trng . 2010;45(3):253-258.
18. Gusmer PB, et al. Labral injuries: Accuracy of detection with unenhanced MR imaging of the shoulder. Radiology . 1996;200(2):519-524.
19. Kibler WB, et al. Scapular dyskinesis and its relation to shoulder pain. J Am Acad Orthop Surg . 2003;11(2):142-151.
20. Cofield RH, et al. Diagnosis of shoulder instability by examination under anesthesia. Clin Orthop Relat Res . 1993;291:45-53.

Suggested readings

Burkhead WZ, Jr, et al. Treatment of instability of the shoulder with an exercise program. J Bone Joint Surg Am . 1992;74:890-896.
Level of evidence: Level 4
Summary: Only 16% of patients with traumatic instability responded to the rehabilitation program, compared with 80% of the atraumatic patients
Farber AJ, et al. Clinical assessment of three common tests for traumatic anterior shoulder instability. J Bone Joint Surg Am . 2006;88(7):1467-1474.
Level of evidence: Diagnostic, Level 1
Summary: A prospective evaluation of 363 patients undergoing shoulder arthroscopy (46 of which for anterior instability) suggests that anterior apprehension and relocation signs are most specific for anterior glenohumeral instability
Silliman JF, et al. Classification and physical diagnosis of instability of the shoulder. Clin Orthop Relat Res . 1993;291:7-19.
Level of evidence: Diagnostic, Level 5
Summary: This article provides a comprehensive approach to a patient with instability. Detailed physical examination pearls are included as well
Taylor DC, et al. Pathologic changes associated with shoulder dislocations. Arthroscopic and physical examination findings in first-time, traumatic anterior dislocations. Am J Sports Med . 1997;25:306-311.
Level of evidence: Prognostic, Level 1
Summary: Traumatic anterior glenohumeral dislocations result in Bankart lesions and Hill-Sachs lesions in young patients
CHAPTER 3 Beach chair and lateral decubitus setup—pros and cons

COL, Edward D. Arrington, MD, CPT(P) Stephen A. Parada, MD, LTC Bryant G. Marchant, MD

Key points

Arthroscopic shoulder procedures are becoming increasingly popular as technology and arthroscopic instruments continue to evolve.
Shoulder surgeons routinely use either the lateral decubitus position or the beach chair position for their cases, or their choice depends on the planned procedure.
No difference has been proven in outcomes between lateral decubitus and beach positioning for shoulder arthroscopy procedures.
Proper setup, including positioning and draping, is essential regardless of the planned patient position.
Complications are rare: traction injuries may occur with the lateral decubitus position, whereas neurovascular injuries and cerebral hypoperfusion may result from the beach chair position.

Introduction
Shoulder arthroscopy and arthroscopic shoulder procedures have gained widespread popularity in the diagnosis and treatment of many pathologic shoulder conditions. Shoulder arthroscopy can be performed in either the lateral decubitus or beach chair position, and optimal positioning is essential for successful shoulder arthroscopic procedures. Positioning is routinely based on the surgeon’s familiarity with the arthroscopic shoulder orientation and the potential need for additional surgical procedures, such as an open procedure. Regardless of the position used, adequate positioning should allow for maximum access for surgery about the shoulder, the ability to move and rotate the shoulder, and ergonomic handling of arthroscopic instruments.
Positioning the patient correctly and safely can be a challenge during shoulder surgery, whether or not it is done arthroscopically or as an open procedure. Some shoulder surgeons use one position exclusively for all procedures regardless of the anticipated pathology in order to create familiarity with the setup. Other shoulder surgeons, after preoperative planning, routinely plan the positioning depending on the specific nature of the case and based on the anticipated pathology. While it is rare that a particular procedure can be performed exclusively in a certain position, pros and cons, as well as various complications, are specific to each position.

Lateral decubitus
Although the shoulder arthroscopy was first performed in 1931, it was not as used as extensively as knee arthroscopy until the 1980s, when its use became more popular. The lateral decubitus position has been a traditional position for shoulder arthroscopy, and it is now used exclusively by many surgeons. Lateral decubitus positioning is facilitated through the use of several different types of commercially available traction apparatus. This equipment, allows weight to be used to pull traction both longitudinally on the arm and laterally at the axilla to permit lateral translation of the glenohumeral joint. Distraction of the glenohumeral joint provides optimum visualization during arthroscopic procedures. 1 - 3 In the lateral decubitus position, the surgeon and assisting surgeon can function on both the anterior and the posterior aspects of the shoulder, while ideally visualizing separate monitors ( Fig. 3-1 ).

FIGURE 3-1 Overview of the lateral decubitus operating room setup.
(Modified from a sketch by David J. Wilson, MD.)

Description of setup ( figs. 3-1 to 3-12 )
After induction of anesthesia, the patient is placed in the lateral decubitus position on a padded table with the well side down. The operating room table setup can be augmented with a gel pad or bean bag. Care is taken to pad all bony prominences. Particular attention is specifically directed to the proximal fibula of the downside leg in order to protect the peroneal nerve from compression. A pillow is also placed between the legs. A small gel pad is used as an axillary roll to reduce any risk of compression of the downside axilla. The head is padded so that the longitudinal axis of the neck is in a neutral position, and not abducted or adducted. The down ear is padded and the eyes protected during the case.

FIGURE 3-2 Operating room bed setup with bean bag and sheet.

FIGURE 3-3 Padded arm board for the down elbow.

FIGURE 3-4 Axillary roll. This type is an inflatable axillary roll; however, an IV bag wrapped in a towel also works well.

FIGURE 3-5 Patient positioned with two people holding while the vacuum suction to the bean bag is applied.

FIGURE 3-6 At the edge of the bean bag where the leg meets the bag is a sharp point that should be padded to avoid potential pressure sores.

FIGURE 3-7 A pillow under the bottom leg and between the bottom and top leg are used to prevent any leg compression injuries.

FIGURE 3-8 Two towels are used on top of the bean bag, and then tape is secured to the table over the towels to secure the patient firmly to the table. Care is taken not to apply too much pressure or to squeeze in too tightly the bean bag.

FIGURE 3-9 A, Patient setup. B, Posterior view of the lateral decubitus position using a beanbag. C , Predraping padded lateral decubitus position using a commercially available lateral position system.
( A modified from a sketch by David J. Wilson, MD.)

FIGURE 3-10 A, Operative arm balanced suspension. Superior view of the lateral decubitus position. B, With operative setup. The arm is usually abducted between 45 and 60 degrees.
( A modified from a sketch by David J. Wilson, MD.)

FIGURE 3-11 Final setup. The patient is turned 90 degrees (or up to 180 degrees) away from the anesthesia machine in order to facilitate anterior and posterior access to the shoulder.

FIGURE 3-12 Final balanced suspension setup with the arm abducted about 50 degrees and a lateral strap is used to facilitate the visualization of the glenohumeral joint. Care must be taken to ensure the lateral suspension strap is around a padded arm sleeve.
To support the body in the lateral decubitus position, a bean bag is utilized. Excessive trunk motion or loss of positioning can occur if the bean bag loses suction pressure. This may be minimized with the use of straps or tape around the trunk, securing the patient to the operating room table. Alternatively, commercially available lateral positioning systems, such as those commonly used for hip arthroplasty cases, also may be used to provide a more stable support without compromising the intraoperative position of the patient. In the lateral decubitus position, the patient is tilted approximately 20 to 30 degrees posterior to orient the glenoid parallel to the floor. 4
The drapes are applied judiciously in an effort to maximize the surgical field about the shoulder, both anteriorly and posteriorly. For an arthroscopic case, two arthroscopy drape drains can be used to collect as much effluent as possible. The operative side axilla is commonly sealed off with a sterile sponge and a sterile adhesive after prepping. Planned incision sites are made away from acne and pustules if possible to avoid potential contamination with Proprionibacterium. 5
The arm is placed into a padded sleeve with the thumb pointing toward the ceiling and then is attached to one of the commercially available traction systems. These systems consist of a support that attaches to the end of the table and then uses a pulley system with weights to pull longitudinal balanced suspension on the arm and lateral traction in the axilla to obtain glenohumeral joint distraction. 1 - 3 These pulleys and weights can be adjusted to provide abduction and forward flexion of the shoulder. The ideal forward flexion is 20 to 30 degrees and the ideal abduction is 25 to 45 degrees, although most surgeons adjust the abduction and forward flexion to personal preferences. Intraoperative changes in glenohumeral abduction, forward flexion, and lateral translation position are obtained easily by adjusting the pulley system. Intraoperative rotation of the humeral head can be adjusted by changing the position of the arm in the sleeve or by rotation of the entire sleeve.



Advantages of the lateral decubitus position
The lateral decubitus position has the following advantages:
1. It maintains steady joint distraction that enhances visualization in the glenohumeral joint and subacromial space.
2. It provides better access to anterior, inferior, and posterior shoulder procedures.
3. The risk for cerebral hypoperfusion is decreased.
4. Surgeon fatigue is decreased because the arms and hands are working near the waist level.

Disadvantages of the lateral decubitus position
The lateral decubitus position has the following disadvantages:
1. Lateral anatomic shoulder orientation may be difficult.
2. There is less ability to rotate the shoulder.
3. Conversion to an open procedure is more difficult.
4. Difficult anesthesia airway management.

Complications
Potential complications from the lateral decubitus position include minor transient traction paresthesias, malpositioning complications, compression neurapraxia, and life-threatening pulmonary embolus.
Traction injuries are reported to have occurred from long arthroscopic procedures or those cases using excessive traction weight. Current recommendations include limiting traction to 2 hours and using less than 12 lb of longitudinal traction and less than 7 lb of lateral traction. Traction injuries usually are due to stretch and resolve over time, although permanent brachial plexus injuries have been reported. 6 , 7 Overtightening or improper positioning of the arm positioning sleeve also can cause compression and injury to the antebrachial cutaneous nerve. In addition, excessive traction has been associated with decreased arterial oxygen saturation using pulse oximetry. 8
Malpositioning complications include pressure injuries over the bony prominences, pressure injuries to the eyes and ears, and neck traction injuries. Care should be taken to pad all bony prominences, pad the down ear and protect the eyes during the case. The head is padded so that the neck is in a neutral position and not abducted, adducted, or rotated.
Compression neuropathies occur secondary to compression over superficial nerves. Particular attention is specifically directed to the proximal fibula of the downside leg in order to protect the peroneal nerve from compression. A pillow also is placed between the legs to protect both legs. A small gel pad is used as an axillary roll to reduce any risk of compression of the downside axilla.
Pulmonary embolus, while having significant morbidity and mortality associated with it, is a rare occurrence after arthroscopic surgery. 9

Beach chair
The beach chair position for shoulder arthroscopy utilizes the standard position used most frequently for open shoulder procedures. The advantages of the beach chair position include an anatomic shoulder orientation, greater freedom of shoulder motion including internal and external shoulder rotation, an easier conversion to an open procedure, and simplified anesthesia airway management. The disadvantages of the beach chair position are the greater risk of using hypotensive anesthesia and maintenance of minimum systolic pressure necessary to maintain cerebral perfusion, no standardized glenohumeral joint distraction, and the need for an assistant or a commercially available arm holding device to maintain the desired arm position. In the beach chair position, the surgeon and assisting surgeon can function on both the anterior and the posterior aspects of the shoulder, while ideally visualizing separate monitors.

Description of setup ( figs. 3-13 to 3-20 )
After induction of anesthesia, the patient is positioned supine on a standard or beach chair table. All bony prominences of the lower extremities are well padded. The patient is then placed into 10 to 15 degrees of Trendelenburg, with the hips flexed from 45 to 60 degrees and the knees flexed at 30 degrees. 4 , 10 , 11 The head is secured in a well-padded headrest in a neutral position with the ears padded and the eyes protected during the case. The hips and knees are flexed, and all bony prominences of the lower extremities are well padded. The nonoperative arm can be placed in a secure holder, a sling, or on an arm board, padding the elbow to protect the ulnar nerve.

FIGURE 3-13 A and B, A leg positioner is important to maintain a comfortable position for the patient and to ensure that the pelvis is level and against the back of the beach chair portion of the bed.

FIGURE 3-14 A foam facemask may be used to secure the head in position.

FIGURE 3-15 The kidney areas are held in with kidney protectors to position the patient on the bed. Cushioning (gel-pad or foam) should be used to prevent pressure sores.

FIGURE 3-16 A and B, Ideally, two people work together to place the patient into the beach chair position. One person lifts up the patient on the beach portion of the chair, while the other secures the head.

FIGURE 3-17 A and B, The head is secured with a foam facemask. Care should be taken to ensure that the neck is in a neutral position, and (C) that the facemask does not cover any mucosal or sensitive areas.

FIGURE 3-18 A, Some beach chairs have an attachment that may be slid medially to expose the posterolateral scapula. B, When slid medially, the back holder should have one to two towels placed against the medial scapular border in order to stabilize the scapula for the procedure.

FIGURE 3-19 A, The legs are then put into final position, ensuring that the leg pad is up against the buttocks, and the buttocks and low back are against the beach chair and not slumped. B, The peroneal nerve at the knee also should be checked to ensure that there is no pressure on it during the case, and then (C) the patient is placed into final position.

FIGURE 3-20 A, B, C, and D, Final positioning with the arm reduced to a pneumatic arm positioner. It is easier to reduce the arm to the arm holder that has been previously placed on the pneumatic arm positioner.
As with the lateral decubitus position, the drapes are applied judiciously in an effort to maximize the surgical field over the entire shoulder both anteriorly and posteriorly. For an arthroscopic case, one arthroscopy drape can be used under the axilla to collect as much effluent as possible. The axilla is commonly sealed off with a sterile sponge and a sterile adhesive after prepping. As before, planned incision sites are made away from acne and pustules if possible to avoid potential contamination with Proprionibacterium. 5
The operative arm is either placed in a commercially available sterile arm positioning device, controlled by an assistant, or placed on a well-padded Mayo stand. This allows for unimpeded positioning of the glenohumeral joint without distortion of the intra-articular anatomy, with minimal to no traction on the brachial plexus.
The beach chair position allows access to both the anterior and posterior aspects of the shoulder without placing the arm under undue tension across the joint and surrounding soft tissues. Anesthesiologists have direct access to the airway, and there may be less bleeding in the upright position with hypotensive anesthesia. 12
Perhaps one of the biggest advantages of the beach chair position is the ease of conversion to an open procedure if necessary. It is almost always possible to convert to an open procedure without needing to reposition or redrape the patient. Although this is not often required during an arthroscopic procedure, a conversion to an open procedure can add significant time in the operating room if the patient requires repositioning or redraping.



Advantages of the beach chair position
Advantages of the beach chair position include the following:
1. Operative arm range of motion is increased.
2. Conversion to open procedure is easier.
3. Anatomic orientation of the glenohumeral joint is normal.
4. Access to the anterior shoulder is better.
5. Anesthesiologists have direct access to the airway, and there may be less joint or subacromial bleeding in the upright position because of hypotensive anesthesia. 12

Disadvantages of the beach chair position
Disadvantages of the beach chair position include the following:
1. Additional assistance or a commercially available arm position is needed.
2. The risk for cardiovascular and cerebral complications is increased.
3. There is potential for more difficult access to the inferior, posterior, and superior areas of the glenohumeral joint.
4. The need for an arm holder and table incurs additional expense.

Complications
Although cerebrovascular events during surgery can be devastating when they occur, they are exceedingly rare. A recent survey of American Shoulder and Elbow Surgeons (ASES) Society revealed that of approximately 200,000 surgeries performed in the beach chair position, there were eight recorded cerebrovascular events (0.004%). 12 It has been reported that hypoperfusion events may be related to errors in blood pressure measurement. Therefore blood pressure should be measured at the level of the heart instead of on the calf, and not allowing blood pressure levels to drop below 80% of normal has been recommended. 13 Obese patients are at increased risk because of compression of the abdominal vena cava, which decreases venous return.

Summary
In summary, both the beach chair and the lateral position may be used to perform almost any shoulder procedure, although specific cases may be more readily completed in a certain position. Each of these positions carries some specific risk; however, potential complications are rare. Most shoulder surgeons would agree that perhaps the biggest impact on the case is the familiarity of performing the specific procedure in the planned position. Surgeons should be exposed to both the beach chair and the lateral position during their training so that they can choose their position of choice in their practice.
The views expressed in this article are those of the authors and do not reflect the official policy or position of the Department of the Army, Department of Defense, or the United States Government.

References

1. Andrews JR, et al. Arthroscopy of the shoulder: Technique and normal anatomy. Am J Sports Med . 1984;12:1.
2. Gross RM, et al. Shoulder arthroscopy: A modified approach. Arthroscopy . 1985;1:156.
3. Johnson LL. The shoulder joint. An arthroscopist’s perspective of anatomy and pathology. Clin Orthop Relat Res . 1987;223:113.
4. Peruto CM, et al. Shoulder arthroscopy positioning: Lateral decubitus versus beach chair. Arthroscopy . 2009;25:891.
5. Committee on Complications of the Arthroscopy Association of North America. Complications in arthroscopy: The knee and other joints. Arthroscopy . 1986;2:253.
6. Curtis AS, et al. Complications of shoulder arthroscopy. Arthroscopy . 1992;8:395.
7. Weber SC, et al. Complications associated with arthroscopic shoulder surgery. Arthroscopy . 2002;18:88. (supp)
8. Hennrikus WL. Lateral traction during shoulder arthroscopy: Its effect on tissue perfusion measured by pulse oximetry. Am J Sports Med . 1995;23:444.
9. Hariri A. Pulmonary embolism following thrombosis of the brachial vein after shoulder arthroscopy. A case report. Orthop Traumatol Surg Res . 2009;95:377.
10. Skyhar MJ, et al. Shoulder arthroscopy with the patient in the beach-chair position. Arthroscopy . 1988;4:256.
11. Warner JP. Shoulder arthroscopy in the beach chair position: Basic set-up. Op Tech Orthop . 1991;2:147.
12. Friedman DJ, et al. Prevalence of cerebrovascular events during shoulder surgery and association with patient position. Orthopedics . 2009;32:256.
13. Papadonikolakis A, et al. Avoiding catastrophic complications of stroke and death related to shoulder surgery in the sitting position. Arthroscopy . 2008;24:481.

Suggested readings

Committee on Complications of the Arthroscopy Association of North America. Complications in arthroscopy: The knee and other joints. Arthroscopy . 1986;2:253.
Level of evidence: 4
Summary: This article reports the results of a questionnaire sent to members of the Arthroscopy Association of North America surveying complications in arthroscopic surgery, including shoulder surgery. There were 14,329 arthroscopic shoulder cases reported, with the average surgeon performing only 2.37 shoulder arthroscopic cases monthly
Friedman DJ, et al. Prevalence of cerebrovascular events during shoulder surgery and association with patient position. Orthopedics . 2009;32:256.
Level of evidence: 4
Summary: This article reports the results of a questionnaire sent to 287 members of the American Shoulder and Elbow Surgeons Society surveying preference of patient positioning for surgery and prevalence of cerebrovascular events during surgery. The majority of surgeons averaged >300 shoulder cases annually, with most surgeons preferring beach chair position. In this study, beach chair positioning did not appear to increase the risk of an intraoperative cerebrovascular event
Hennrikus WL, Lateral traction during shoulder arthroscopy: Its effect on tissue perfusion measured by pulse oximetry. Am J Sports Med . 1995;23:444-1995.
Level of evidence: 4
Summary: Three different methods of shoulder traction during arthroscopy were evaluated on arterial oxygen saturation through pulse oximetry. The use of vertical traction in addition to longitudinal traction was found to result in ablation of the oxygen saturation in 25/30 patients compared to 1/30 patients when longitudinal traction alone was used
Papadonikolakis A, et al. Avoiding catastrophic complications of stroke and death related to shoulder surgery in the sitting position. Arthroscopy . 2008;24:481.
Level of evidence: 5
Summary: This article is a review of complications relating to cerebrovascular events during surgery performed on the patient in the sitting, or beach chair, position. It also describes the changes in blood pressure due to the relative position of the arm compared to the heart and how this leads to inaccurate blood pressure measurements
Skyhar MJ, et al. Shoulder arthroscopy with the patient in the beach-chair position. Arthroscopy . 1988;4:256.
Level of evidence: 5
Summary: This article is a review of use of the beach chair position for arthroscopic shoulder surgery in 50 consecutive patients. Routine arthroscopy, arthroscopic subacromial decompression, and arthroscopic stabilization procedures were all performed without complication. Positioning technique is described and advantages are listed
CHAPTER 4 Open and arthroscopic instrumentation for instability repair

Eric J. Strauss, MD, Joseph U. Barker, MD, Kevin C. McGill, MD, MPH, Nikhil M. Verma, MD

Key points

Appropriate anesthesia, operating room setup, and instrumentation enable the surgeon to effectively manage capsulolabral pathology using both open and arthroscopic techniques.
A combination of regional and general anesthesia reduces the need for inhalational agents and assists with postoperative pain control.
The findings of a proper examination under anesthesia before patient positioning can support the preoperative diagnosis and the planned operative approach.
During arthroscopic stabilization procedures, a thorough knowledge of both standard and accessory portals provides the surgeon with 360 degree access to the glenohumeral joint.
Some surgeons prefer open stabilization for patients participating in contact sports, those with glenoid or humeral head bone defects that require concomitant treatment, humeral avulsion of the glenohumeral ligaments, and those who have failed prior arthroscopic stabilization.
Various options are available with respect to suture anchors and suture passing instruments in the management of glenohumeral instability.

Introduction
Management of glenohumeral instability is a common, complex problem with a spectrum of pathology ranging from acute, traumatic dislocation to atraumatic, multidirectional instability. In most cases, once nonoperative management fails to resolve the patient’s symptoms, surgical stabilization is indicated. 1 , 2 Both open and arthroscopic techniques have been used with success in the surgical treatment of symptomatic glenohumeral instability. For each operative approach, proper patient positioning, surgical technique, and instrumentation are paramount to enable the surgeon to effectively manage various types of pathology involving the bone, tendon, labrum, and capsule. This chapter reviews these elements, providing an overview of the preparation and operative setup for open and arthroscopic shoulder stabilization.

Anesthesia
Both open and arthroscopic stabilization procedures can be performed under general anesthesia, regional anesthesia (interscalene block; Fig. 4-1 ), or a combined approach. The choice is based on patient preference, the anesthesiologist, the surgeon, and planned patient positioning. A combination of general and regional anesthesia has the benefits of reducing the need for inhalational agents, helping maintain the mean arterial pressure between 70 and 90 mm Hg for intraoperative visualization, and assisting with postoperative pain control. Additionally, it obviates the worry of the difficulty associated with the intraoperative conversion to general anesthesia with the patient in the lateral decubitus or beach chair position, which may become necessary.

FIGURE 4-1 Interscalene block. Regional anesthesia via an interscalene technique allows for successful blockade of the supraclavicular, suprascapular, axillary, and radial nerves during shoulder surgery.
Regional anesthesia via an interscalene technique allows for the successful neural blockade of the upper extremity, including the supraclavicular, suprascapular, axillary, and radial nerves during shoulder surgery. Successful placement of the block is highly technique dependent and the anesthesiologist may employ a nerve stimulator or ultrasound to help accurately localize the placement of the local anesthetic solution ( Fig. 4-2 ). Although the exact combination of local anesthetics varies depending on the anesthesiologist, institution, and anticipated duration of the surgical procedure, the interscalene technique has been found to be an effective method of regional anesthesia for shoulder surgery. Brown et al compared interscalene block to general anesthesia for use in shoulder surgery and found that interscalene block was safe and effective, provided excellent intraoperative analgesia and muscular relaxation, and resulted in fewer postoperative side effects and hospital admissions. 3 Limited potential complications of the interscalene block include injection-associated brachial plexopathy, peripheral neuropathy, pneumothorax, and cardiac arrhythmias. 4 Recent studies of regional anesthesia for shoulder surgery have reported complication rates ranging from 1.1% to 3.7%. 4 - 6

FIGURE 4-2 Ultrasound guidance for interscalene block. Ultrasound may be used to help localize the needle during placement of an interscalene block.
Although many cases can be completed under regional anesthesia only, general anesthesia may offer some additional advantages. In our experience, patient positioning in the lateral decubitus position is poorly tolerated in the awake patient and may be an indication for a general anesthetic. In addition, the interscalene block will not cover the region around the axilla, which is T1 sensory-innervated, and may result in pain during open procedures. Finally, the ability to provide complete paralysis during procedures performed under a general anesthetic may facilitate retraction and exposure during open surgery. In these cases, we prefer to use a combined approach with both general and regional anesthetic, which allows decreased intraoperative use of inhalational agents and effective postoperative pain control.

Examination under anesthesia
With the patient supine on the operating room table, before positioning, an examination under anesthesia (EUA) is performed on both shoulders, allowing for an assessment of range of motion and stability ( Fig. 4-3 ). The findings of the EUA can help support the preoperative diagnosis and the planned operative approach. 7 , 8 Range of motion is assessed by bringing each shoulder into maximal forward flexion and internally and externally rotating the shoulder with the arm both at the side and at 90 degrees of abduction. Anterior and posterior translation of the humeral head on the glenoid can be evaluated with a load-shift test, in which the shoulder is abducted to 60 degrees in neutral rotation, and an axial load combined with anterior or posterior translation force is applied to the proximal humerus. 9 , 10 The observed translation is recorded and compared to the opposite side. The amount of humeral head translation during these provocative maneuvers can be graded on a three-grade scale ( Table 4-1 ). 11 Grade I translation is one in which the humeral head translates to but not over the glenoid rim. Grade II instability describes translation of the humeral head over the rim of the glenoid followed by spontaneous reduction when the load is removed. Translation of the humeral head over the glenoid rim, which becomes locked and irreducible denotes Grade III instability.

FIGURE 4-3 Examination under anesthesia of the right shoulder. The examiner’s left hand rests on the top of the patient’s shoulder, allowing for the application of either anterior or posterior directed forces.
(Reprinted with permission: Cofield RH, et al: Evaluation and classification of shoulder instability: With special reference to examination under anesthesia. Clin Orthop Relat Res 223:32–43, 1987.)
Table 4-1 Three-grade Scale for Anterior and Posterior Translation of the Humeral Head on the Glenoid During the Examination Under Anesthesia Grade Characteristics I Humeral head translates to, but not over, the glenoid rim II Humeral head translates over the glenoid rim III Humeral head translates over the glenoid rim and becomes locked and irreducible
Posterior stability can be further assessed by forward flexing the shoulder to 140 degrees, which allows the greater tuberosity to clear the acromion, and adducting to 15 degrees as a posteriorly directed force is applied. Finally, an inferiorly directed force on the humerus can be applied to assess for the presence of a sulcus sign. Given that the rotator interval tightens normally in external rotation, the sulcus sign should be performed in both the neutral position and in external rotation to evaluate for pathologic laxity. In all cases, shoulder translation in all quadrants should be compared to the opposite extremity, which may provide further insight into the normal state for an individual patient.


Pearls of Anesthesia and the Examination Under Anesthesia

Combination regional and general anesthesia assists with operative visualization by allowing for maintenance of the mean arterial blood pressure between 70 and 90 mm Hg in addition to providing postoperative pain control.
During the examination under anesthesia, the patient’s range of motion and glenohumeral stability can be assessed and compared to the contralateral side.
A load-shift test can evaluate both anterior and posterior translation of the humeral head on the glenoid, with grading performed on a three grade scale.


Pitfall of Anesthesia and the Examination Under Anesthesia

Complications associated with interscalene block are rare but include injection associated brachial plexopathy, peripheral neuropathy, pneumothorax, and cardiac arrhythmias.

Arthroscopic shoulder stabilization
As techniques and instrumentation have evolved and surgical experience has increased, the arthroscopic management of glenohumeral instability has expanded. Compared to traditional open techniques, arthroscopic shoulder stabilization allows for smaller incisions; decreased soft-tissue dissection; improved visualization of glenohumeral anatomy and pathoanatomy; reduced perioperative morbidity and postoperative pain; and perhaps, easier postoperative rehabilitation. 9 , 12 Recent studies have demonstrated that the arthroscopic treatment of instability has clinical outcomes that are equivalent to open repairs. 9 , 13 - 18

Patient positioning
Positioning in the beach chair and lateral decubitus positions for arthroscopic shoulder surgery is described in Chapter 3 . Please refer to Chapter 3 for further details.

Arthroscopy equipment setup
Once the patient is prepped, positioned, and draped, the necessary equipment for the arthroscopic procedure is set up ( Fig. 4-4 ). The arthroscopic tower containing the monitor, light source, control box, and shaver power source is positioned on the side opposite to the operative site. The fluid irrigation pump and the control box for the radiofrequency device also are placed on the opposite side of the patient. A Mayo stand is positioned distally, above the patient’s waist, serving to hold the instrumentation that will be used frequently during the operative procedure. Finally, the surgical scrub technician’s back table is positioned behind the surgeon and his or her assistant for easy access.

FIGURE 4-4 Arthroscopy set. Necessary surgical equipment for arthroscopic shoulder stabilization.
Fluid management for the arthroscopic procedure is controlled by the fluid irrigation pump or through a gravity-driven system, which infuses sterile saline into the glenohumeral joint. Our preference is to use a pump system to maintain hemostasis and distention, and to improve visualization. In general, the fluid pressure within the joint is kept between 35 and 45 mm Hg. While intermittent increases in fluid pressure may be required for visualization purposes, extended periods of increased pressure can lead to fluid extravasation into the soft tissues, causing swelling and distortion of normal anatomy. Adequate hemostasis is critical to maintaining visualization during the procedure and can be facilitated by maintaining a mean arterial blood pressure of 70 to 90 mm Hg and the addition of epinephrine to the fluid bags. At our institution, we employ 1.5 ampules of 1:1000 epinephrine added to each 5-L bag of irrigation fluid.

Skin marking and portal placement
Following patient positioning and prepping of the surgical field, the superficial bony shoulder anatomy is marked out with a surgical marking pen, helping to guide the later placement of arthroscopic portals. Important anatomic landmarks to identify include the coracoid process, clavicle, acromioclavicular joint, and outline of the acromion process, paying close attention to the anterolateral and posterolateral corners of the acromion ( Fig. 4-5 ).

FIGURE 4-5 Skin marking. Following patient positioning and draping, the superficial bony anatomy of the shoulder is marked out with a surgical marking pen, helping guide the later placement of arthroscopic portals. Important landmarks to identify include the coracoid process, clavicle, acromioclavicular joint and the outline of the acromion process, paying close attention to the location of the anterolateral and posterolateral corners of the acromion.
Portal positioning during arthroscopic stabilization should not be underestimated; correct positioning facilitates repair while malpositioning can significantly complicate surgery. The procedure begins with the creation of a posterior viewing portal and introduction of the arthroscope into the glenohumeral space ( Fig. 4-6 ). When the patient is in the beach chair position, the posterior portal is typically placed 2 cm inferior and 1 to 1.5 cm medial to the posterolateral corner of the acromion. Alternatively, manual palpation of the posterior “soft spot,” localizing the joint space, can facilitate positioning of the posterior portal. This soft spot represents the interval between the infraspinatus and teres minor muscles, centered over the glenohumeral joint space. Secondary to lateral distraction of the joint space in the lateral position, the posterior portal should be placed 2 cm inferior and in line with the posterolateral aspect of the acromion.

FIGURE 4-6 Posterior viewing portal. The position of the posterior viewing portal varies, depending on whether the patient is in the beach chair or lateral decubitus position. When the patient is in the beach chair position the posterior portal is typically placed 2 cm inferior and 1 to 1.5 cm medial to the posterolateral corner of the acromion (blue circle). Secondary to lateral distraction of the joint space in the lateral position, the posterior portal is typically placed 2 cm inferior and in line with the posterolateral aspect of the acromion (red circle).
For stabilization procedures, four accessory portals allow 360 degree access to the glenohumeral joint space. Two anterior portals are typically established, one anterosuperior and one mid-glenoid ( Fig. 4-7 ). The anterosuperior portal is created using an outside-in technique starting with an 18 gauge spinal needle inserted 1 cm anterior to the acromion and 2 cm lateral to the coracoid process. The needle should be visualized entering the glenohumeral joint high within the rotator interval, just medial and posterior to the biceps tendon. A 5.0 to 6.5 mm cannula is inserted through this portal for instrumentation and suture passage. Care must be taken to place this portal high in the interval, allowing space for a second portal to be placed inferiorly.

FIGURE 4-7 Anterior portals. For arthroscopic stabilization, typically two anterior portals are established, one anterosuperior (A) and one mid-glenoid (B).
The mid-glenoid portal also is created using an outside-in technique, aiming to establish the portal just above the superior edge of the subscapularis tendon, as lateral as possible to facilitate anchor insertion into the glenoid. Sufficient spread between the two portals should be maintained. Secondary to the passage of larger suture passing instruments through this portal, a larger 8.25-mm twist-in cannula is inserted. Alternatively, either portal can be created with an inside-out technique, using a Wissinger rod passed through the posterior cannula, positioned in the desired location within the rotator interval.
An additional anterior accessory portal can be useful during stabilization procedures, depending on the location of the patient’s pathology. As described by Davidson and Tibone, the anteroinferior 5 o’clock portal provides direct, linear access to the anteroinferior aspect of the glenoid, the typical site of a Bankart lesion. 19 This portal is established just lateral to the conjoined tendon in the lower third of the subscapularis muscle, passing lateral to the musculocutaneous nerve and superolateral to the axillary nerve. Either an outside-in or inside-out technique can be used for portal creation. With the inside-out technique, the humerus is adducted, better exposing the subscapularis muscle. The position of the portal should be first localized with a spinal needle. Our preference is to use this portal for percutaneous anchor insertion to the most anterior-inferior anchor position. Alternatively, a cannula can be placed to access the joint, although insertion through the thick subscapularis muscle and tendon can be difficult.
Access to the posterior and inferior glenohumeral joint is accomplished via an accessory posterolateral or 7 o’clock portal created 4 cm inferior to the posterolateral corner of the acromion. This portal is lateral to the standard posterior portal, allowing appropriate angle for anchor insertion in the posterior or inferior glenoid. Again, the portal should be localized via spinal needle localization followed by Wissinger rod placement ( Fig. 4-8 ). The portal can be used for percutaneous anchor placement, or a large bore cannula can be used for further instrumentation. This portal allows access to the inferior aspect of the glenoid and the axillary pouch for anchor insertion and capsular plication.

FIGURE 4-8 Spinal needle localization for 7 o’clock portal. Access to the posterior and inferior glenohumeral joint can be accomplished via an accessory posterolateral or 7 o’clock portal created 4 cm inferior to the posterolateral acromion.
Accessory superolateral, anterolateral, and posterolateral (Port of Wilmington) portals also can be created for the surgical repair of superior labrum anterior and posterior (SLAP) tears. As shown by Laurencin et al, the superolateral portal is placed just lateral to the acromion on a line drawn between the coracoid process and the acromion. 20 The accessory anterolateral portal is placed 1 cm lateral to the anterior aspect of the acromion, allowing for an appropriate angle for anchor insertion during SLAP repair. The portal of Wilmington is used in the repair of posterosuperior labral tears. It is established 1 cm lateral and 1 cm anterior to the posterolateral corner of the acromion, at an angle of 45 degrees. Because these portals may violate the supraspinatus and infraspinatus tendon, most surgeons choose to avoid the insertion of a cannula, choosing to insert the drill guide, drill, and anchor percutaneously.

Open shoulder stabilization
Although controversial, some authors have reported that indications for open stabilization over an arthroscopic technique include patient participation in contact or collision sports, the presence of glenoid or humeral head bone defects that require concomitant treatment, humeral avulsion of the glenohumeral ligaments, and failed prior arthroscopic stabilization. 21

Patient positioning
For cases of anterior glenohumeral instability, open stabilization is performed with the patient placed supine on the operating room table, with the head of the table raised to 30 degrees and the arm abducted 45 degrees on a well-padded arm board. Posterior instability is typically addressed with the patient in the lateral decubitus or “sloppy” lateral position, allowing access to the posterior aspect of the shoulder.

Surgical approaches
The anterior approach to the glenohumeral joint utilizes the deltopectoral interval, taking advantage of the internervous plane between the axillary nerve and the medial and lateral pectoral nerves. A longitudinal surgical incision is made starting just lateral to the coracoid process and extending distally along Langer’s lines in line with the anterior axillary crease. Subcutaneous dissection will identify the cephalic vein, which marks the deltopectoral interval. The vein is dissected free and retracted laterally, allowing for the interval to be developed down to the level of the clavipectoral fascia. The fascia is then incised at the lateral border of the conjoined tendon from the level of its coracoid attachment to a point distal to the subscapularis tendon. The coracoacromial ligament can then be divided to assist in exposure of the superior glenohumeral capsule. A self-retaining Kolbel retractor is then placed to provide medial-lateral retraction, exposing the underlying subscapularis tendon. The subscapularis tendon can be taken down laterally or split horizontally to expose the underlying joint capsule. The interval between the subscapularis and the underlying joint capsule is then developed using a combination of blunt and sharp dissection. This exposes the anterior aspect of the glenohumeral joint, allowing for assessment of capsular, bone, and labral pathology, which is addressed as indicated.
Open treatment of posterior shoulder instability begins with a vertically oriented incision centered over the glenohumeral joint, extending from the junction of the scapular spine and acromion to the axillary crease. If a diagnostic arthroscopy was performed before the open procedure, the posterior viewing portal can be incorporated into the middle of the incision. Subcutaneous dissection is performed to the level of the fascia overlying the deltoid. The fascia is incised in line with the deltoid fibers allowing for a blunt split of the deltoid directly over the glenohumeral joint. Once through the deltoid, the fascia overlying the infraspinatus and teres minor is exposed. Self-retaining retractors can be placed into the wound to improve the operative exposure. Exposure of the posterior glenohumeral joint capsule can then be achieved by either creating a horizontal split within the infraspinatus muscle or by using the interval between the infraspinatus and teres minor muscle. If the latter approach is used, the surgeon must be careful to avoid dissecting inferior to the teres minor because of the proximity of the axillary nerve. The interval between the infraspinatus and the underlying joint capsule is then developed using a combination of blunt and sharp dissection. Once exposed, the posterior capsule can be split, allowing exposure of the underlying posterior labrum.

Tools and implants for open and arthroscopic stabilization procedures
Whether the operative approach is open or arthroscopic, the surgical goals of surgery for shoulder instability are the same. The site of capsulolabral injury is identified, the tissue is mobilized, the repair site is prepared, and the tissue is reapproximated to the glenoid. However, given the limited access provided during arthroscopic surgery, specialized instrumentation is required for suture passage, suture manipulation, and knot tying.
For arthroscopic stabilization techniques, a standard arthroscopy set is required that includes an arthroscopic probe, a sharp elevator, a tissue grasper, a suture loop or crochet hook, a suture passing device, and a knot pusher. As noted previously, at least two arthroscopic cannulas are used, typically a 5 to 6 mm and an 8.25 mm. A specialized arthroscopic elevator is required to mobilize and release the torn labrum in order to achieve anatomic reduction. A motorized shaver is used to debride the torn tissue and prepare a bony bed for repair. In cases of very hard bone, a bone-cutting shaver or an arthroscopic burr may be necessary. Once the capsulolabral tissue is mobilized and the glenoid rim prepared, suture anchors are inserted to facilitate fixation of the soft tissue to bone. A variety of anchors are commercially available, each with slightly different suture material and insertion technique. Depending on the site of the labral injury and the associated choice of portals, suture passing ensues followed by tying of arthroscopic knots, recreating a functional capsulolabral bumper with capsular plication to restore glenohumeral stability.


Pearls

A 3.5 mm or smaller bone cutter shaver is optimal for preparation of the glenoid for instability repair. Its small size and bone cutting/burring ability allow it to easily prepare glenoid bone. Larger shavers may have difficulty fitting in between the capsulolabral tissue and the glenoid.
Numerous elevators are available to subperiosteally elevate the labrum off the glenoid neck. Care must be taken not to “shred” the labrum or inadvertently create radial tears in the labrum. Elevators with one sharp edge or a spoon-shaped elevator may help prevent inadvertent tearing of the labrum
Open stabilizations require a basic orthopaedic surgery set and a small fragment set, which include self-retaining retractors; ring (Rowe or Fukuda) retractors; Army-Navy retractors ( Fig. 4-9 ); osteotomes; needle drivers; and drill bits, if bone tunnels are used. In anterior capsulolabral reconstruction, a drill set can be used to drill holes in the anterior glenoid rim for suture anchors that will be used to advance the inferior capsular flap and suture it into a more superior position. For an anteroinferior capsular shift, small Darrach retractors can be used to define the superior border of the subscapularis tendon in order to close the rotator interval before performing the capsular shift without involving the supraspinatus. A ball-tipped pusher can be used to push the humeral head posteriorly to enhance exposure of the capsule, a periosteal elevator may be helpful to reflect the subscapularis tendon, and a needle-nosed rongeur can be used to mark a starting point for drilling holes for the suture anchors placed in the glenoid rim. A self-retracting device, such as the Kolbel, is especially helpful to place just under the conjoint tendon and subdeltoid to allow for maximal exposure.

FIGURE 4-9 Retractors used in open stabilization. In addition to a basic orthopaedic surgery set, open stabilizations require retractors to aid in exposure.
Following capsulolabral mobilization, fixation to the prepared bony rim can be accomplished using bone tunnels or suture anchors, depending on the surgeon’s preference. Absorbable sutures (2-0) are used for closing deep fascia and 2-0 Prolene subcuticular sutures are used for skin closure.

Suture anchors
In an effort to reapproximate torn capsulolabral tissue to the glenoid, suture anchors were developed as an alternative to bone tunnels for shoulder stabilization procedures. While their size, composition, eyelet type, implantation technique, number, and type of associated sutures vary among manufacturers, the general principles of suture anchor use remain the same. Whether used in arthroscopic or open stabilization, the suture anchor must provide a stable fixation point for the attached suture, have adequate pull-out strength, and allow for the tying of an arthroscopic knot. Recent innovations with respect to suture anchors include the use of bioabsorbable or biocompatible material; the use polyetheretherketone (PEEK) material, which is radiolucent and more closely approximates the modulus of human cortical bone; the introduction of knotless designs; and the incorporation of high-strength core sutures. 22
Suture anchors are available in a wide variety of sizes, depending on their intended application and the quality of the patient’s bone. For stabilization procedures, we typically use 2.3 mm anchors, reserving larger 2.9 mm anchors for cases of osteoporotic bone ( Fig. 4-10 ). Whereas historically metal anchors were used for stable fixation to the glenoid, the recent trend is toward anchors composed of bioabsorbable or PEEK material. We have transitioned to the use of PEEK suture anchors in an attempt to avoid the potential cystic reaction that has been noted with other bioabsorbable materials (poly-L-lactide [(PLLA)], polylactic-co-glycolic acid [(PLGA)]). Additional variables to consider with respect to suture anchor use include the implantation technique, number of associated sutures (single-loaded versus double-loaded), and the type of suture material included in the anchor. In a recent study from our institution (publication pending, AJSM, 2009) comparing different repair constructs for anterior Bankart repair, we found similar ultimate failure loads and displacement with cyclic loading between single-loaded anchors tied with simple knots, single-loaded anchors tied with a horizontal mattress knot, and a double-loaded anchor tied with simple knots.

FIGURE 4-10 A 2.3 mm PEEK suture anchor. PEEK suture anchors can be used for stable fixation of capsulolabral tissue to the glenoid. PEEK anchors have gained popularity in an attempt to avoid the potential cystic reaction that has been noted with other bioabsorbable materials.
Anchor placement should closely follow the manufacturer’s specifications with regard to the size and depth of pilot hole preparation and the depth of anchor insertion. With a number of options available in the marketplace, it is up to the surgeon to be familiar with the specifications, implantation technique, and characteristics of their suture anchor of choice for glenohumeral stabilization. In all cases, one must be most concerned about depth of insertion. Multiple reports of significant chondral injury have been associated with proud anchor placement, and injury can occur with any material including metal, bioabsorbable, and PEEK suture anchors.

Suture passing instruments
Once the suture anchor is inserted into the glenoid, suture passage through the capsulolabral tissue can be accomplished with a number of different instruments and techniques. Arthroscopic penetrators of various angles can be used to pierce the tissue and grasp one or both of the suture limbs for later knot tying with simple or horizontal mattress configurations ( Fig. 4-11 ). These penetrating devices are most useful in the upper half of the glenoid where a direct line from cannula to passage site is available. In addition, the width of the instrument may leave a large defect in the capsule or labrum during passage.

FIGURE 4-11 Arthroscopic suture passing instruments. Arthroscopic penetrators of various angles can be used to pierce tissue and grasp one or both suture limbs during capsulolabral repair.
In the inferior half of the glenoid, curved suture shuttle devices are required to allow for suture passage and capsular shift. Suture shuttling for capsulolabral repair can be accomplished using reusable passers such as the Spectrum (ConMed Linvatec, Largo, FL), which employs tissue penetrating hooks of 12 different angles and configurations ( Fig. 4-12 ). Once the tip of the penetrating hook is inserted through the capsulolabral tissue, a monofilament suture such as a 0 Prolene suture is advanced through the instrument. This Prolene suture is grasped through one of the anterior cannulas and tied to one of the suture limbs from the suture anchor. The suture passing device is then removed, allowing for shuttling of the suture limb through the capsulolabral tissue using the monofilament suture. In addition, multiple similar single-use suture passing devices are available in various shapes, angles, and curvatures.

FIGURE 4-12 Spectrum suture passer. Suture shuttling for capsulolabral repair can be accomplished using a reusable passer such as the Spectrum.
(ConMed Linvatec, Largo, FL), which employs tissue penetrating hooks of 12 different angles and configurations.


Pearls
Numerous suture passing instruments are available. In order to accomplish a capsulolabral shift, the device usually needs not only to be inserted and rotated but also translated to shift the tissue to a proper tensioning location.
Different angles of the suture passing devices may accomplish different shifts of capsulolabral tissue and also may account for different trajectory with cannula positioning.
Similar to the number of options available with respect to suture anchors, the operating surgeon should be familiar with different suture passing instruments and techniques in order to successfully manage labral tears of different sizes and locations.

Conclusion
Both open and arthroscopic techniques have been used with success in the surgical treatment of symptomatic glenohumeral instability. For each operative approach, a thorough knowledge of proper patient positioning, surgical technique, available implants, and instrumentation enable the operating surgeon to effectively and consistently manage these cases.

References

1. Brophy RH, et al. The treatment of traumatic anterior instability of the shoulder: Nonoperative and surgical treatment. Arthroscopy . 2009;25(3):298-304.
2. Schenk TJ, et al. Multidirectional instability of the shoulder: Pathophysiology, diagnosis, and management. J Am Acad Orthop Surg . 1998;6(1):65-72.
3. Brown AR, et al. Interscalene block for shoulder arthroscopy: Comparison with general anesthesia. Arthroscopy . 1993;9(3):295-300.
4. Lenters TR, et al. The types and severity of complications associated with interscalene brachial plexus block anesthesia: Local and national evidence. J Shoulder Elbow Surg . 2007;16(4):379-387.
5. Weber SC, et al. Scalene regional anesthesia for shoulder surgery in a community setting: An assessment of risk. J Bone Joint Surg Am . 2002;84-A(5):775-779.
6. Bishop JY, et al. Interscalene regional anesthesia for shoulder surgery. J Bone Joint Surg Am . 2005;87(5):974-979.
7. Bonner K. Patient positioning, portal placement, normal arthroscopic anatomy, and diagnostic arthroscopy . Philadelphia: Saunders; 2008.
8. Mazzocca AD, et al. Shoulder: Patient positioning, portal placement, and normal arthroscopic anatomy. Philadelphia: Saunders; 2004.
9. Bottoni CR, et al. Suture anchor fixation for shoulder instability . Philadelphia: Saunders; 2008.
10. Tzannes A, et al. An assessment of the interexaminer reliability of tests for shoulder instability. J Shoulder Elbow Surg . 2004;13(1):18-23.
11. Altchek DW, et al. T-plasty modification of the Bankart procedure for multidirectional instability of the anterior and inferior types. J Bone Joint Surg Am . 1991;73(1):105-112.
12. Green MR, et al. Arthroscopic versus open Bankart procedures: A comparison of early morbidity and complications. Arthroscopy . 1993;9(4):371-374.
13. Bottoni CR. Arthroscopic repair of primary anterior dislocations of the shoulder. Tech Shoulder Elbow Surg . 2001;2(1):2-16.
14. Fabbriciani C, et al. Arthroscopic versus open treatment of Bankart lesion of the shoulder: A prospective randomized study. Arthroscopy . 2004;20(5):456-462.
15. Kim SH, et al. Arthroscopic anterior stabilization of the shoulder: Two to six-year follow-up. J Bone Joint Surg Am . 2003;85-A(8):1511-1518.
16. Kim SH, et al. Bankart repair in traumatic anterior shoulder instability: Open versus arthroscopic technique. Arthroscopy . 2002;18(7):755-763.
17. Mazzocca AD, et al. Arthroscopic anterior shoulder stabilization of collision and contact athletes. Am J Sports Med . 2005;33(1):52-60.
18. Tauro JC. Arthroscopic inferior capsular split and advancement for anterior and inferior shoulder instability: Technique and results at 2- to 5-year follow-up. Arthroscopy . 2000;16(5):451-456.
19. Davidson PA, et al. Anterior-inferior (5 o’clock) portal for shoulder arthroscopy. Arthroscopy . 1995;11(5):519-525.
20. Laurencin CT, et al. The superior lateral portal for arthroscopy of the shoulder. Arthroscopy . 1994;10(3):255-258.
21. Pagnani M. Open repair of anterior shoulder instability . Philadelphia: Saunders; 2008.
22. Barber FA, et al. Suture anchor materials, eyelets, and designs: Update 2008. Arthroscopy . 2008;24(8):859-867.

Suggested readings

Fabbriciani C, et al. Arthroscopic versus open treatment of Bankart lesion of the shoulder: A prospective randomized study. Arthroscopy . 2004;20(5):456-462.
Level of evidence: 1
Summary: In this prospective, randomized clinical study including 60 patients with traumatic anterior shoulder instability, patients were divided into two treatment groups: open versus arthroscopic repair of an isolated Bankart lesion. The treatment groups were similar with respect to patient age, gender, hand dominance, number of dislocations, time interval between first dislocation and surgical treatment, and pathologic findings. Outcomes were assessed and compared at 2 years of follow-up. The mean Constant and Rowe shoulder scores were not significantly different between treatment groups and neither group had recurrence of shoulder instability. Although outcome scores were similar, patients treated with arthroscopic repair had better postoperative range of motion than those managed with open surgical repair
Kim SH, et al. Arthroscopic anterior stabilization of the shoulder: Two to six-year follow-up. J Bone Joint Surg Am . 2003;85-A(8):1511-1518.
Level of evidence: 4
Summary: This study evaluates the results of arthroscopic Bankart repair in 167 patients with traumatic recurrent anterior instability. The mean age of the cohort at the time of surgery was 25 years. Both pre- and postoperatively, patients were assessed using three outcome scoring systems (Rowe score, UCLA shoulder rating scale, American Shoulder and Elbow Surgeons [ASES] score) and two subjective scoring systems (pain and function Visual Analog Scale [VAS] scales). At a mean follow-up of 44 months, all shoulder scores significantly improved compared to preoperative values. According to the Rowe score, 95% of patients in this cohort had good to excellent results, and 91% of patients returned to greater than 90% of their preinjury activity level. Postoperative recurrence occurred in 4% of patients (1 dislocation, 2 subluxation, and 4 positive results on postop anterior apprehension testing). Following operative repair, patients experienced a mean 2-degree loss of external rotation
Kim SH, et al. Bankart repair in traumatic anterior shoulder instability: Open versus arthroscopic technique. Arthroscopy . 2002;18(7):755-763.
Level of evidence: 3
Summary: This case-control study compared the results of open and arthroscopic Bankart repair in 89 shoulders presenting with traumatic, unilateral, anterior shoulder instability. Thirty shoulders were treated arthroscopically and 59 shoulders were managed with open surgical repair. At a mean of 39 months postoperatively, 86.6% of patients in the open treatment group had good to excellent results compared to 91.5% in the arthroscopic group. Patients in the arthroscopic treatment group had slightly higher scores in the Rowe and UCLA scoring systems. The incidence of recurrent instability was 6.7% among patients in the open repair group compared with 3.3% in the arthroscopic group. Postoperative range of motion and the percentage of patients returning to their preinjury level of activity were similar between the treatment groups
Mazzocca AD, et al. Arthroscopic anterior shoulder stabilization of collision and contact athletes. Am J Sports Med . 2005;33(1):52-60.
Level of evidence: 4
Summary: This case series looked at 18 collision and contact athletes younger than 20 years of age who underwent arthroscopic anterior shoulder stabilization as treatment of symptomatic shoulder instability. Surgical management included suture anchor repair of the torn labrum, capsulorrhaphy, and rotator interval closure when indicated. At a mean follow-up of 37 months (range 24 to 66 months), 2 collision athletes (football players) experienced recurrent dislocations after the procedure. None of the contact athletes (wrestlers, soccer players) experienced recurrent instability. Based on their findings, the authors concluded that participation in collision and contact athletics is not a contraindication for arthroscopic anterior shoulder stabilization
Weber SC, et al. Scalene regional anesthesia for shoulder surgery in a community setting: An assessment of risk. J Bone Joint Surg Am . 2002;84-A(5):775-779.
Level of evidence: 4
Summary: This retrospective study evaluated 218 patients who received scalene block regional anesthesia for shoulder surgery over a 3-year period. All blocks in this series were performed using a standard blunt-needle technique with the patient awake and a nerve stimulator used to localize the brachial plexus. Adjunctive general anesthesia was used in 82% of cases. Block failure occurred in 13% of patients, and 33% of patients required intravenous pain medication immediately upon arrival in the recovery room. Complications related to the block occurred in 6 patients, including one grand mal seizure, one episode of cardiovascular collapse, and 4 cases of severe respiratory distress. The mean duration of the block was 9 6 4.6 hours
CHAPTER 5 Sutures and glenoid anchors for instability

F. Alan Barber, MD, FACS, Scott A. Hrnack, MD

Key points

The surgeon should be familiar with the types and composition of suture materials and suture anchors being used in today’s marketplace.
Bioabsorbable and biocomposite suture anchors have shown similar strengths, improved postoperative visualization on imaging, and allowed for easier revision surgery than metallic suture anchors.
A surgeon should master at least one sliding and nonsliding knot. A sliding knot backed up by at least three, preferably four, reversed half hitch knots with switching posts should ensure adequate knot security.
Suture anchors have many potential failure sites; however, the suture-anchor interface, and bone-anchor interface are most frequently sites of failure for glenohumeral stability procedures.
Suture materials and anchors should be tested for both single tested pullout and fatigue failure in a laboratory before introduction into the market.

Introduction
Shoulder instability is a common problem especially in the young and athletic population. This instability can be unidirectional (anterior or posterior) or multidirectional. In addition, the instability can manifest as a complete dislocation or lesser subluxations. The glenoid is a shallow concave socket, and its depth is increased at least 50% by the attached glenoid labrum. Providing glenohumeral stability to augment the labrum are the capsuloligamentous structures. Anteriorly static stability is provided by three glenohumeral ligaments. The superior, middle, and inferior glenohumeral ligaments resist anterior and inferior dislocation of the humeral head. The inferior glenohumeral ligament has anterior and posterior bands with an intervening sling and is the primary stabilizer to anterior humeral translation at 90 degrees abduction. The anterior band reciprocally tightens in abduction and external rotation, and the posterior band tightens with forward elevation and internal rotation.
When the glenohumeral joint dislocates, damage may occur to the bone, labrum, and the ligamentous attachments. The extent of this damage and the physiologic characteristics of the individual sustaining the dislocation influence the prognosis and have a bearing upon the appropriate treatment. A significant bone fragment may require reattachment of replacement. An engaging Hill-Sachs lesion may require a posterior humeral anchor to attach the infraspinatus tendon to fill the defect in the humeral head. Anchoring techniques may be required to reattach the fracture fragment. Concurrent with bony, labral, and ligamentous disruption, significant capsular stretching is a real possibility. To maximize the chances of success, the surgical treatment for shoulder instability must repair not only the torn labrum and bone but also address any stretched capsular tissue.
Arthroscopic stabilization techniques have advanced as a result of two major developments: suture anchors and ultra-high molecular weight polyethylene (UHMWPE) suture material. Although these anchors and sutures are now routinely used for both open and arthroscopic procedures, there can be no question that the innovation targeted arthroscopic procedures. Over time biomechanical studies on the properties of suture anchor fixation have lead to improvements in these anchors. The obvious benefits of stronger sutures have led to their wide acceptance.
Product innovation is not the only reason arthroscopic techniques have become the new “gold standard” for shoulder instability surgery; technique changes also play a major role. Thumbtacklike devices that reattach the torn capsuloligamentous structures medially on the glenoid neck have been abandoned because of the recognition that they are creating an anterior labral periosteal sleeve avulsion (ALPSA) lesion instead of reestablishing normal anatomic relationships. The recognition of the need for at least three anterior fixation points, locating the anchor sites on top of the glenoid cartilage (rather than medially on the neck), considering rotator interval closure to address inferior subluxation, adding posterior inferior sutures when appropriate, including a capsular plication stitch to address a patulous capsule, and better knot-tying techniques have all resulted in clinical outcomes consistent with those of open techniques.
Suture anchor designs are procedure specific. Some designs are best suited for holding multiple sutures in osteoporotic bone (rotator cuff repairs), or they allow static sutures to slide through the anchor eyelet with the option for independent tensioning after anchor insertion (lateral row cuff anchors). The focus of this chapter is on the anchors and sutures best suited for use in the glenoid labrum. The common features that make anchors well suited for a shoulder instability application include smaller size, reduced requirement for multiple sutures, and shorter lengths to avoid penetrating through the inferior glenoid at the 6 o’clock position.
Although not an absolute requirement but certainly preferable, biodegradable material is very attractive in a suture anchor, especially for one destined to be placed in the glenoid. While metal anchors were commonly used in the past, biodegradable anchors have comparable pull out strength; do not create problems in revision surgery or postoperative imaging; 1 and, with the introduction of biocomposite materials, offer the prospect of osteoconductive behavior leading to their replacement with bone.
This chapter covers the current state of sutures and suture anchors appropriate for glenohumeral instability, including the materials and their properties, various knot configurations, biocomposite materials, and suture anchor characteristics. Each subject area concentrates on areas orthopaedic surgeons should be familiar with in order to make informed decisions when selecting these implants for patient use.

Suture material
Desirable material properties for an arthroscopic suture are similar to those for any surgical suture and include good handling characteristics, biocompatibility, adequate strength, and good loop and knot security. What distinguishes a superior arthroscopic suture is greater strength for a standard size and a low friction surface conducive to tying in the arthroscopic environment.
Many sutures are available and in addition to material and size differences can be monofilament, braided, blended, and absorbable or nonabsorbable. Each of these features has advantages and disadvantages of which the surgeon should be aware. A common biodegradable monofilament suture (polydioxanone or PDS) is adaptable to the arthroscopic environment and frequently used in shoulder instability surgery. PDS is often used as a shuttling suture for passing braided sutures through the glenoid capsuloligamentous tissue. It is often used for rotator interval closure stitches because it can be inserted directly with common suture hook devices (Spectrum system, Linvatec, Largo, FL; Ideal suture hook, Depuy Mitek, Rayham, MA) without the need for a shuttling device or suture. Because polydioxanone suture material degrades in a relatively short interval, its choice for suturing the rotator interval is based on the likelihood that should tightening be excessive, the degradation of the suture will allow the overconstrained tissue to stretch out with therapy. PDS degrades steadily after insertion, losing both mass and strength. At 2 weeks in vivo, PDS sutures retained 60% of the original strength and by 6 weeks 40%. The suture was almost completely reabsorbed by 9 weeks. Although PDS is easy to use and has relatively good strength, the stiffness associated with it results in PDS having a “memory,” with the tendency for knots tied with it to unravel if an insufficient number of backup half hitches are not tied. Nonetheless, PDS is a commonly used suture in glenohumeral instability surgery.
Until recently, braided polyester suture was the most commonly used suture in shoulder surgery. Although different brands were available, Ethibond (Ethicon Inc., Somerville, NJ) was the “gold standard” because it was easier to handle, more pliable, and passed easily through tissues because of a polybutylate coating. This coating is not present on Mersilene (Ethicon Inc., Somerville, NJ) and other braided polyester sutures. This changed when Arthrex (Naples, FL) introduced FiberWire suture, which has a braided polyester coat around a central core of multiple small strands of ultra-high molecular weight polyethylene (UHMWPE).
By way of background, the United States Pharmacopeia (USP) is an official public standards–setting authority. The USP standard correlated suture size and suture strength and set standard ranges for both. Following the USP standard, all number 2 size sutures were to have a breaking strength within a specific range. From the standpoint of the arthroscopic surgeon, this presented a problem. Unless considerable finesse was used during arthroscopic knot tying, the leverage applied to the suture by a knot pusher could break the suture. Additionally, braided polyester sutures were inclined to fray against the eyelet of a metal suture anchor or the insertion instrumentation, further diminishing the suture’s resistance to breakage. The introduction of FiberWire redefined suture performance. Although initially ignored by suture manufacturers, other arthroscopic instrumentation companies realized the advantages of the concept of “super strength” suture materials.
Dyneema fiber is an ultra-high-strength polyethylene fiber that offers a maximum strength combined with a minimum weight. It is up to 15 times stronger than quality steel and up to 40% stronger than aramid (aromatic polyamide) fibers on a weight-for-weight basis. This fiber was made available to many companies with various braid designs and was introduced into the field of arthroscopic surgery under several different brand names. These brand names include Hi-Fi (ConMed Linvatec, Largo, FL), Force Fiber (Stryker Endoscopy, San Jose, CA), Ultrabraid (Smith & Nephew, Andover, MA), Magnum Wire, (Axya Medical, Beverly, MA, and ArthroCare, Sunnyvale, CA) and MaxBraid PE (Arthrotek, Warsaw, IN) ( Table 5-1 ). The newer UHMWPE-containing sutures have been shown to have 2 to 2.5 times the ultimate strength of traditional braided polyester suture and a 500-fold increase in resistance to fraying. 2
Table 5-1 Common Ultra-High Molecular Weight Polyethylene–Containing Sutures Suture Composition FiberWire (Arthrex: Naples, FL) Braided polyester outer covering, UHMWPE fiber core Orthocord (DePuy Mitek, Raynham, MA) UHMWPE and PDS (polydioxanone) Hi-Fi (ConMed Linvatec, Largo, FL) Braided UHMWPE Ultrabraid (Smith & Nephew, Andover, MA) Braided UHMWPE Force Fiber (Stryker Endoscopy, San Jose, CA) Braided UHMWPE MaxBraid PE (BioMet Sports Medicine, Warsaw, IN) Braided UHMWPE MagnumWire (ArthroCare, Sunnyvale, CA) Braided UHMWPE
Subsequent to the release of the Dyneema family of braided sutures, Ethicon released Orthocord suture, which is used in many of the DePuy Mitek suture anchors. Orthocord is unique in that it combines UHMWPE with a degradable material. The size No. 2 consists of a combination of UHMWPE (32%) and polydioxanone (PDS) (68%) and is coated with polyglactin 910. The Orthocord design comprises a PDS core with a UHMWPE sleeve. 3 This configuration is designed to leave a lower profile suture after the PDS has dissolved while retaining strength from the outer sleeve. It should be noted that the percentage of PDS and UHMWPE differs slightly with the different sizes of Orthocord suture. 4
Although these UHMWPE-containing sutures have distinct advantages in arthroscopic shoulder instability surgery, concerns about mechanical irritation, articular cartilage erosion, tissue abrasion while running the suture through tissue, and impingement persist. As yet, no completely absorbable ultra-high-strength suture exists, although it is a desirable goal.


Pearls for Suture Material
New sutures containing ultra-high molecular weight polyethylene (UHMWPE) are now the gold standard.
UHMWPE-containing sutures are more likely to slip than braided polyester and have different tying characteristics: they are harder to break, have a different feel, and can cut your hand more easily.
Orthocord is the only new high strength suture that combines UHMWPE with a biodegradable suture material.

Suture performance and knots
Knot security and loop security are the two basic principles in arthroscopic knot tying. Loop security is defined as the ability of the suture loop to hold the tissue and to maintain a tight suture loop as the knot is tied. A knot with good loop security will not allow the backsliding of the knot once tied, which ensures continued proper tension between the repaired tissues. Loop security is influenced by the suture’s mechanical properties and by the tension the surgeon applies while tightening the knot. Knot security is the ability of the knot to resist slippage when a load is applied. Both knot and loop security vary with the different suture materials.
Arthroscopically tied knots consist of an initial slip knot that removes any slack at the tissue and a locking mechanism, usually a series of half hitches. When a surgeon ties knots by hand, he or she is able to apply square throws. In contrast, arthroscopic half hitches result from asymmetric tension being applied to the two strands. This feature may result in a less secure knot and may explain why arthroscopic knots fail at a greater rate than hand-tied square knots. To counter this tendency of half hitches to slide, more complex sliding locking knots have been developed. These knots have more internal resistance and result in greater knot and loop security.
For arthroscopic shoulder instability surgery (as with any arthroscopic knot tying), the surgeon should master two types of knots: nonsliding and sliding knots. Nonsliding knots are used in cases when the suture is caught, frayed, or otherwise cannot slide freely. These consist of a series of half hitches that vary the direction of the throw and alternate the post around which the half hitch is thrown. The most common nonsliding knot ( Fig. 5-1 ), the Revo knot, has been shown to test well compared with sliding knots. 5 , 6 The first two half hitches of the Revo knot are throwing in the same direction on the same post. The third half hitch reverses that direction but uses the same post. These three half hitches are tensioned at this point using a “past pointing” technique with a single lumen knot pusher. Two additional half hitches are then thrown using the other suture limb as the post and alternating the direction of the throw.

FIGURE 5-1 The Revo knot step-by-step. The Revo (multiple alternating half hitches) knot is the most common nonsliding knot. A, The first two half hitches of the Revo knot are throwing in the same direction on the same post. B, The third half hitch reverses that direction but uses the same post. These three half hitches are tensioned at this point using a “past pointing” technique with a single lumen knot pusher. C, and D, Two additional half hitches are then thrown using the other suture limb as the post and alternating the direction of the throw. E, Final Revo knot configuration.
(Copyright by F. Alan Barber, MD, FACS.)
When the suture slides freely through the suture anchor eyelet and soft tissue, sliding knots can be used. A major advantage of a sliding joint is that it is assembled entirely outside the cannula. When tying a sliding knot, the post strand is shortened to less than half the length of the loop strand. This is done because as the knot is delivered down the cannula and into the joint, the post limb is pulled out of the joint, lengthening it, and the loop limb slides into the joint, shortening it. Once the main knot is delivered to the fixation site, it is reinforced with alternating half hitches on alternating posts. Traction must be maintained on the post of a sliding knot while the half hitches are thrown and locked. This is not needed for a sliding locking knot.
Sliding knots can be subdivided into locking and nonlocking knots. The Duncan knot is a sliding nonlocking knot. To tie a Duncan loop ( Fig. 5-2 ), the sutures are grasped between the thumb and index finger and a loop is created by passing the loop strand over the post. The loop strand continues in the same direction to place four subsequent throws around the post limb. The free end of the loop limb is the passed through the original loop created, and the knot is tightened to remove the slack from the knot configuration. Once the knot is “policed,” the post strand is pulled and the knot advanced. At least three reversed half hitches should be used to reinforce the knot.

FIGURE 5-2 The Duncan knot step-by-step. The Duncan knot is a sliding nonlocking knot with a strong tendency to slip when tied using high strength sutures. A to D, To tie a Duncan loop, the sutures are grasped between the thumb and index finger and a loop is created by passing the loop strand over the post. The loop strand continues in the same direction to place four subsequent throws around the post limb. E, The free end of the loop limb is the passed through the original loop created, and the knot is tightened to remove the slack from the knot configuration. Once the knot is “policed,” the post strand is pulled and the knot advanced. At least three reversed half hitches should be used to reinforce the knot. F, Final Duncan knot configuration.
(Copyright by F. Alan Barber, MD, FACS.)
Many studies have been published describing the performance and security of various knots tied with Ethibond suture. 7 However, these must now be viewed with caution because recent studies have shown that the performance of UHMWPE-containing sutures differs from that of braided polyester suture (Ethibond). 4 - 6 What is notable and clinically significant is that the UHMWPE-containing sutures are more likely to slip. Consequently, at this point, sliding knots such as the Duncan knot, Weston knot (knots slipped in over 90%), and the Fisherman’s knot cannot be recommended to be used with the newer sutures. Sliding locking knots such as the Samsung Medical Center (SMC) knot ( Fig. 5-3 ), 4 Tennessee slider ( Fig. 5-4 ), and San Diego ( Fig. 5-5 ) knots were stronger and slipped in less than 10% of the tests. 5

FIGURE 5-3 The SMC (Samsung Medical Center) knot is a very consistent sliding locking knot.
(Copyright by F. Alan Barber, MD, FACS.)

FIGURE 5-4 The Tennessee slider knot is a sliding locking knot.
(Copyright by F. Alan Barber, MD, FACS.)

FIGURE 5-5 The San Diego knot is a sliding locking knot.
(Copyright by F. Alan Barber, MD, FACS.)
To tie the SMC knot, the sutures are grasped between the thumb and index finger, and a loop is created by passing the loop strand over the post as in the Duncan loop. Next the loop limb continues under and over both strands again. The loop limb then is passed under the post and between both suture ends and then over the top of the post strand away from the initial loop. A triangular interval is formed between the initial throws over the post strand. The free end of the loop limb is passed from the bottom to the top through this interval under the post strand, and a locking knot is created. If preferred, with the thumb and index finger, release the sutures, and the locking loop can be kept open for later locking, or the entire construct may be “policed” for easier passage into the joint. Once in place, the post strand is pulled firmly, and the knot is locked. After the initial sliding knot is locked, it must be reinforced by reversed half hitches. We prefer to apply four, but some are confident with only three.
The Tennessee slider is a buntline hitch on the post limb followed by a series of reversed half hitches with alternating posts. The buntline hitch also is known as a clove hitch. To start, the loop limb is thrown over and around the post limb and then comes back under the loop limb. It continues around and back over the post limb again in the same counterclockwise direction but is brought back through the interval created between the first pass under the post limb and the second pass over the post limb. At this point, the slack is removed from the knot, and it is advanced into the proper position by pulling on the post limb and pushing with a single lumen knot pusher. Once in position, pulling on the loop limb locks the knot. It is secured with four reversed half hitches.
The San Diego knot, described by Abbi et al, 6 starts with the post limb, with the post limb shortened as much as possible. The loop limb is used to create a slip loop that is tightened securely to remove any slack. A second slip loop is then created using the loop of the initial slip loop and the loop limb, which is passed into the first slip loop to create the two linked slip loops. The first slip loop is tightened securely as the second slip loop is created. However, the second slip loop is left open. The post strand is then passed through the second (and open) slip loop, and the knot is “policed” by taking the slack from the knot. The knot is delivered down the cannula by pulling the post strand and pushing with a single lumen knot pusher. Once the knot is in proper position, the knot is locked by pulling firmly on the loop limb to lock the loop.
Even with the sliding locking knots such as the SMC, Tennessee slider, and San Diego knot, it is necessary to reinforce these with reversed half hitches. We recommend reinforcing these initial knots with four reversed half hitches with reversed posts. Several reports indicate that the SMC knot consistently provides strong knot with good loop security even with UHMWPE-containing suture.
Suture welding of monofilament suture has been described as an alternative to arthroscopic knot tying. Although clinical evidence supports this process, welding is seldom performed. Another option is the use of knotless suture anchors to approximate the tissues. Knotless anchors offer some benefits, including avoiding the need to tie knots, and they limit the placement of sutures in tissue and are not capable of a simultaneous capsular plication with the labral advancement. Also tissue tensioning is linked to the anchor insertion rather than being a separate step associated with knot tying.


Pearls for Knots and Sutures

The surgeon should master two types of knots: nonsliding and sliding knots for arthroscopic shoulder instability surgery.
Sliding locking knots should be reinforced by at least three (preferably four) reversed half hitches.
The Duncan knot, Weston knot, and the Fisherman’s knot should not be tied using UHMWPE-containing sutures because of the risks of knot slipping.
The SMC, Tennessee slider, and San Diego knots slip in less than 10% of tests using UHMWPE-containing sutures.

Suture anchors
Patients undergoing arthroscopic shoulder stabilization are younger with better bone quality than those undergoing a rotator cuff repair. Postoperative immobilization is generally shorter, and the rehabilitation program begins sooner. This leads to stresses being applied sooner to the suture-tissue repair site. On the other hand, the capsulolabral tissue and bone involved in a shoulder instability case are more robust than that encountered with cuff repairs. Consequently the biomechanical properties and design features of an acceptable glenoid anchor will be strikingly different from one used in the humeral tuberosity.
The size and shape of the glenoid require an anchor that will not be as effective in the tuberosity. The nature of the glenoid dictates that successful anchors must be relatively small and hold well in the cortical bone. Some of the current anchors suitable for use in the glenoid are listed in Table 5-2 . The glenoid bone contrasts significantly to the more osteoporotic humeral tuberosities.
Table 5-2 Common Glenoid Suture Anchors Manufacturer Anchor DePuy Mitek, Raynham, MA Lupine BR (2.9 drill, 3.7 mm implant) The Biocryl Rapide (BR) biocomposite is 70%: PLLA(85) co-glycolide(15) + 30% β-tricalcium phosphate (β-TCP) Gryphon P BR (2.4 mm drill)   BioKnotless BR (or plus = PLLA) 3.9 mm × 9 mm Arthrex: Naples, FL Bio-SutureTak (2.4 mm × 12 mm) (3.7 mm × 14 mm) PLDLA   PEEK SutureTak (3.0 mm × 12 mm) (85% PLLA/ 15% β-TCP) Biocomposite PushLock (2.9 mm × 10.7 mm; 3.5 mm ×14 mm) (85% PLDLA/ 15% β-TCP) BioComposite SutureTak (2.4 mm × 12 mm; 3 mm × 14 mm) ConMed Linvatec, Largo, FL BioAnchor, PLLA 3.5 mm × 10.5 mm PLLA   Mini-BioRevo 3.1 mm O.D. × 11 mm SR-PL(96)D(4)LA   Mini-Revo 2.7 mm O.D. × 8.5 mm metal   Impact Suture Anchor 3.5 mm × 10.5 mm SR-PL(96)D(4)LA Smith & Nephew, Andover, MA Bioraptor 2.3 PK 3 mm × 11.6 mm   Kinsa (knotless) 3.0 drill, 3.4 mm × 15.1 mm Stryker Endoscopy, San Jose, CA Xcel anchor PLLA 3 mm   PEEK TwinLoop 3.5 mm double-looped suture eyelets BioMet Sports Medicine Warsaw, IN Hitch anchor: 2.4 mm (PEEK and LactoSorb L15) offset suture loop eyelet L15 is 85% PLLA and 15% PGA; LactoSorb is 82% PLLA and 18% PGA LactoScrew 2.8 mm and 3.5 mm (LactoSorb)   Micromax 2.9 mm and 3.9 mm (LactoSorb) ArthroCare, Sunnyvale, CA ParaSorb PLLA, 3 mm (two #2 sutures)   Parafix Titanium, 3 mm (single #2 suture)
O.D., outer diameter; PEEK, polyetheretherketone; PGA, polyglycolic acid; PLDLA, poly levo dextro lactic acid; PLLA, poly-L-lactic acid.
The anchors best suited for the glenoid rim are smaller in size and range from 2 mm to 3.5 mm. This smaller size meets the requirements of the confined space and dense bone of the glenoid rim. Toggle anchor designs that would not be as appropriate for a decorticated greater tuberosity have a place in the glenoid. The Lupine BR anchor is an example of a toggle anchor ( Fig. 5-6 ). Drill depth and overall anchor length are also factors. Care must be taken to avoid overpenetration of the inferior glenoid near the 6 o’clock position. The length of the drill or anchor may cause either to break through into the axillary space. Conversely, smaller anchors generally have lower load to failure strengths than larger anchors. Therefore, a reasonable balance between anchor size and holding strength must be sought.

FIGURE 5-6 The Lupine BR anchor is an example of a toggle anchor.
(Copyright by F. Alan Barber, MD, FACS.)
Some smaller anchors cannot accommodate two sutures of the size commonly chosen for glenoid capsuloligamentous repair. The Mini-BioRevo is an example of a single eyelet, single suture glenoid anchor ( Fig. 5-7 ). Yet, for some applications in which a single suture per anchor is desired, this does not present a limitation.

FIGURE 5-7 The Mini-BioRevo anchor is a single eyelet, single suture glenoid anchor.
(Copyright by F. Alan Barber, MD, FACS.)
With the widespread acceptance of suture anchors, most initial ineffective designs have been replaced. The currently available anchors will all probably be effective if deployed correctly. Prior concerns about load to failure strength have generally been replaced by decisions based on anchor size, the number of accompanying sutures, the anchor material (anchor and suture), and the surgeon’s preferred technique.
The anchor may be preloaded with between one to three sutures. Our preference is to use an anchor that can accommodate one or two sutures to provide the option for redundant fixation, particularly at the inferior glenoid anchor. The suture material options include a braided polyester suture or an UHMWPE-containing suture. Our preference is to use the UHMWPE-containing sutures for ease of application but in conjunction with a sliding locking knot (either the SMC knot or Tennessee slider). Because of the biodegradable component of the suture, Orthocord is our preferred arthroscopic suture.


Pearls for Suture Anchors

The size and shape of the glenoid require an anchor that will not be as effective in the tuberosity.
Smaller anchors are better suited for the glenoid rim and should have a minor diameter or drill size from 2 mm to 3 mm to avoid excessive bone loss.

Suture anchor materials
The number of surgeons who still favor metallic implants is declining as arthroscopic skills improve and our knowledge of nonmetallic materials expands. As the trend moves further from metal, newer implant materials have been chosen for suture anchors. These include the standard biodegradable polymers (poly-L-lactic acid [PLLA]), co-polymers and stereoisomers of lactide, and nonabsorbable biologically inert polymers (polyetheretherketone [PEEK]). PEEK is an organic crystalline thermoplastic polymer that is chemically resistant, can operate in a wide pH range from 60% sulfuric acid to 40% sodium hydroxide, and resists deformation at high temperatures. Several current glenoid suture anchors are made of PEEK, including the PEEK SutureTak ( Fig. 5-8 ).

FIGURE 5-8 A, The PEEK SutureTak anchor is made of PEEK material. B demonstrates the eyelet of the PEEK anchor up close, showing the orientation and alignment of the suture eyelet to the remainder of the anchor.
(Copyright by F. Alan Barber, MD, FACS.)
Bioabsorbable suture anchors were introduced to help minimize the problems seen with metallic anchors and have gained considerable popularity. 8 These suture anchors were designed to be just as strong and secure as the metallic anchors but to have the ability to degrade slowly over time as the tissue repair healed, becoming more stable. Degradable materials commonly used in suture anchors are polyglycolic acid (PGA), PLLA, poly-D-L-lactic acid (PLDLA), and combinations of these. Slowly degrading biodegradable implants are unlikely to cause the lytic reactions previously seen with rapidly degrading implants made from pure PGA. However, in an effort to reduce the time needed for an implant to degrade, various stereoisomer combinations of PLLA [PD(96%)L(4%)LA or PD(70%)L(30%)LA] and copolymers (PLLA co-PGA) have been introduced that do not cause the lytic response.
The advantages of nonmetallic anchors include better imaging, easier revision (especially troubling with a proud improperly placed metal anchor), diminished concerns about late anchor migration, and less suture abrasion at the eyelet. Although plastic (PEEK) anchors are also radiolucent and can be drilled through during a revision procedure, they present many of the same concerns as a metal anchor (late migration, “permanent”). Also, even if a PEEK anchor may be drilled through during a revision procedure, it is imperative, yet difficult, to remove all the small plastic shavings created during this process. In contrast to the debris created when drilling through a biodegradable implant, PEEK shavings will never disappear and offer the potential to create abrasive injury to the articular cartilage. Finally, because of the age of the patient typically undergoing shoulder instability surgery, having an anchor that degrades over time is attractive because of the patient’s anticipated longevity.
Recently, biocomposite technology has led to the introduction of suture anchors made from bioceramic materials. Beta-tricalcium phosphate (β-TCP) derivatives have demonstrated osteoconductive properties that may result in bone ingrowth into the prior anchor site, or they may enhance material incorporation into host bone. Combinations of biodegradable polymers and β-TCP blend these two substances and result in a material possessing the properties of the two separate materials. For instance, the compressive strength and stiffness of β-TCP is very high, and when blended, imparts these characteristics to the biocomposite.
Biocomposite technology promises to be a significant advancement in arthroscopic implants, and the recently released β-TCP-containing biocomposite suture anchors offer a new direction. Examples of these biocomposite suture anchors on the market today include the Arthrex BioComposite Corkscrew FT (85% PLLA/15% β-TCP); 3.5 mm BioComposite PushLock (85% PLLA/15% β-TCP); and the BioComposite SutureTak, which uses a different biocomposite composed of 15% β-TCP and 85% PLDLA. The DePuy Mitek Lupine BR (see Fig. 5-6 ) and Gryphon BR anchors use still another biocomposite composed of 30% β-TCP and 70% PLGA. The PLGA copolymer present in the Biocryl Rapide (BR) portion of these anchors is made of 15% PGA and 85% PLLA (see Table 5-2 ). Preliminary studies shows that resorption of β-TCP-containing composite materials occurs within 18 to 24 months, followed by significant bone ingrowth by 36 months.
A totally suture-based anchor was recently released. The JuggerKnot 1.4 (Biomet Sports Medicine, Warsaw, IN) is made from a single strand of No. 1 MaxBraid suture that passes through a sleeve of braided polyester suture in a “ V ” configuration. When deployed, this combination creates the anchoring mechanism ( Figs. 5-9 and 5-10 ).

FIGURE 5-9 The JuggerKnot 1.4 anchor is completely suture based.
(Copyright by F. Alan Barber, MD, FACS.)

FIGURE 5-10 There are several areas in which any suture-anchor construct may fail. This figure depicts the potential zones of failure, including, the tissue/suture interface (superficial layer), the suture/anchor interface (middle), and the anchor/bone (deep) interface. All are important components of the suture-anchor construct and all need to work together in order to provide reliable fixation.
(Modified from Nho SJ, et al: Biomechanical fixation in arthroscopic rotator cuff repair. Arthroscopy 23(1):94–102.e1, 2007, Figure 1.)


Pearls for Suture Anchor Materials

Nonmetallic anchors offer the advantages of better postoperative imaging, easier revision, diminished concerns about late anchor migration, and less suture abrasion at the eyelet.
PEEK anchors are radiolucent and can be drilled out for revision procedures. However, they have many of the same concerns as metal anchors (late migration, “permanent”). In addition, when drilling out a PEEK anchor, small plastic shavings are created that may be difficult to remove completely.
Beta-tricalcium phosphate (β-TCP) demonstrates osteoconductive activity and may induce bone ingrowth into the prior anchor site, making it a desirable part of a biocomposite material.

Glenoid anchor techniques
Suture anchors have proven superior to older suture fixation methods for glenohumeral instability. Originally, anchors were made from metal and used with braided polyester sutures. Metal anchor limitations include the risk of suture abrasion at the eyelet, removal difficulties when improperly placed or proud, and the potential for devastating chondral wear. With the introduction of UMWPE-containing sutures, failure by suture breaking and fraying has become less likely. Instead, knot slipping with nonlocking sliding knots (Duncan loop or Weston knot) are more likely. Biodegradable anchor failure at a point in the degradation pathway can lead to anchor fragments or sutures within the joint. Anchor loosening and migration are still possible.
Successful shoulder instability repair is based on optimal anchor placement, adequate advancement of the detached glenohumeral ligaments, preservation and restoration of any detached labrum, and the elimination of a stretched or patulous capsule. Anchor placement should be as close to the 6 o’clock position as reasonable; however, the 5:30 o’clock position on the glenoid works well and can be obtained through the standard mid-glenoid portal. A more inferior anchor location is not necessary because if the capsuloligamentous structures are adequately mobilized from the anterior glenoid neck, they can be captured and a suture passed to allow an adequate advancement. Additionally, the more inferior anchor position risks overpenetration of the inferior glenoid by the drill and subsequent anchor placement into the axilla.
Once advanced, the capsule and inferior glenohumeral ligament can be reattached in place, restoring the anatomy and eliminating any stretched capsule. The anchor site should be drilled upon the glenoid articular cartilage about 1 to 2 mm from the anterior glenoid rim to avoid creating a surgical ALPSA lesion and to achieve placement of the repaired labrum on top of the glenoid. The goal is to fashion a superior shift of the capsule, ligaments, and labral tissue and to ensure that an adequate amount of capsular tissue is imbricated in the repair. The imbrications will vary, depending on the pathology observed but are generally in the range of 5 to 10 mm.
Suture passage can be the most difficult step in arthroscopic shoulder stabilization. The initial stitch should restore the normal anatomic position of the capsulolabral complex, anatomically reapproximate the soft tissue against the glenoid rim, and incorporate any observed soft tissue laxity to restore normal tension.
Glenoid suture anchors can carry a single suture or be double loaded. Double-loaded anchors provide an additional fixation point for the repair or at least a backup in case something goes amiss with the first suture. When using both sutures of a double-loaded anchor, the first suture should be left untied after it is passed. It can be threaded through a suture saver or simply clamped with a hemostat outside the cannula until the second suture is passed. At that time, both are tied.
Suture-passing instruments vary, but the authors prefer a suture hook device. Working the device’s needle hook through the tissue is easier if traction is placed on the tissue. This can be achieved either by grasping the tissue with a device or using a previously placed temporary traction suture. Anchors should be placed 5 mm to 7 mm apart, and if the inferior capsule is still patulous after all sutures are secured, additional capsular plication stitches may be needed.
Some patients with marked inferior subluxation of the humeral head or with clinical signs of hyperlaxity may benefit from a posterior inferior figure-of-eight plication stitch. In addition, a rotator interval stitch 9 also may be used to decrease the intra-articular volume. In cases in which the labral displacement continues to the posterior and inferior glenoid, posterior anchors may be required. Care should be taken to not overtighten the posterior capsule to prevent motion loss. The goal is a “balanced” repair that balances the posterior capsular tightness with the anterior instability repair. Provencher et al have demonstrated that the intact posteroinferior or anteroinferior glenoid labrum provides fixation strength similar to a glenoid suture anchor. 10


Pearls for Suture Management
The consistent and reproducible management of sutures in shoulder stabilization procedures is facilitated by keeping several things in mind.
Use a threaded cannula (preferably clear) for all instrumentation and suture management steps. The cannula should remain constantly in the joint throughout the suture-passing and knot-tying process to avoid tissue capture.
When using a suture shuttling device, do not retrieve the shuttling device out the same cannula through which it was introduced.
Do not cross sutures. Select the suture limb closest to the tissue you want it to secure. For instance, with an inferior glenoid anchor, select the inferior-most suture from the anchor to pass through the tissue. This will avoid one suture trapping the other or interposing itself between the tissue and bone.
Before withdrawing a suture from the joint, grasp it with a ring grasper near the anchor and have the assistant alternately pull both arms of the suture. By observing which direction each arm slides, you can determine the correct arm to secure and the correct arm to pull. This avoids inadvertent unloading of the anchor.
If multiple sutures are used from a single anchor, wait to tie the sutures until all have been passed through the tissue. To avoid tangling the sutures, suture savers can be used to keep them organized and separate. An alternative is to pull the unused sutures out an alternate cannula.
Tie the knots on the suture arm that passes through the soft tissue. In this way, the knot will not be near the articular surface.
When passing reversed half hitches to secure the initial sliding locking knot, do not tighten the half hitch unless you can actually see it slide down the cannula and become fully seated at the fixation point. Placing the half hitches by feel can result in a prematurely locked knot should one of the half hitches not advance completely down to the fixation point.
Mastering arthroscopic knot tying is the cornerstone to successful arthroscopic shoulder instability surgery. Appropriate suture selection, optimal knot configuration, and proficient surgical skills contribute to the outcome.

Conclusions
Advances in sutures and suture anchors offer improved techniques for arthroscopic glenohumeral instability surgery. Metallic anchors have been mainly replaced by nonmetallic anchors including bioabsorbable, the newer biocomposite, and PEEK (plastic) suture anchors. The biocompatible absorbable anchors are just as strong and durable as the metallic and plastic anchors and facilitate easier postoperative imaging and revision surgery. As new anchors continue to be introduced into the market place, surgeons should be familiar with the composition and behavior of any new suture anchor they contemplate using.

References

1. Barber FA, et al. Cyclic load testing and ultimate failure strength of biodegradable glenoid anchors. Arthroscopy . 2008;24:224-228.
2. Wust DM, et al. Mechanical and handling properties of braided polyblend polyethylene sutures in comparison to braided polyester and monofilament polydioxanone sutures. Arthroscopy . 2006;22:1146-1153.
3. Barber FA, et al. Sutures and suture anchors—update 2006. Arthroscopy . 2006;22:1063-1069.
4. Swan KGJr, Baldini T, McCarty EC. Arthroscopic suture material and knot type: An updated biomechanical analysis. Am J Sports Med . 2009;37:1578-1585.
5. Barber FA, et al. Cyclic load and failure behavior of arthroscopic knots and high strength sutures. Arthroscopy . 2009;25:192-199.
6. Abbi G, et al. Evaluation of 5 knots and 2 suture materials for arthroscopic rotator cuff repair: Very strong sutures can still slip. Arthroscopy . 2006;22:38-43.
7. Hassinger SM, et al. Biomechanical characteristics of 10 arthroscopic knots. Arthroscopy . 2006;22:827-832.
8. Nho SJ, et al. Bioabsorbable anchors in glenohumeral shoulder surgery. Arthroscopy . 2009;25:788-793.
9. Mologne TS, et al. The addition of rotator interval closure after arthroscopic repair of either anterior or posterior shoulder instability: Effect on glenohumeral translation and range of motion. Am J Sports Med . 2008;36:1123-1131.
10. Provencher MT, et al. A biomechanical analysis of capsular plication versus anchor repair of the shoulder: Can the labrum be used as a suture anchor. Arthroscopy . 2008;24:210-216.

Suggested readings

Barber FA, et al. Cyclic load testing and ultimate failure strength of biodegradable glenoid anchors. Arthroscopy . 2008;24:224-228.
Summary: Biodegradable glenoid anchors (BioKnotless, Lupine Loop, BioPushLock, BioSutureTak, BioFasTak, BioAnchor, and BioRaptor) showed no differences in ultimate failure strength after cyclic loading. Most displacement occurred in the first 100 cycles. Anchor failures were principally by the anchor pulling out of bone. The BioSutureTak also failed by the suture loop eyelet pulling out of the anchor body, and the BioPushLock failed by the suture slipping past anchor.
Barber FA, et al. Cyclic load and failure behavior of arthroscopic knots and high strength sutures. Arthroscopy . 2009;25:192-199.
Summary: The Revo, Tennessee slider, San Diego, and SMC knots were less likely to slip than the Duncan loop and Weston knot, especially when tied using high-strength sutures. While stronger than braided polyester sutures, newer sutures containing ultra-high molecular weight polyethylene have a greater tendency to slip. Backing up knots with four reversed half hitches with switched posts does not guarantee knot security.
Mologne TS, et al. The addition of rotator interval closure after arthroscopic repair of either anterior or posterior shoulder instability: Effect on glenohumeral translation and range of motion. Am J Sports Med . 2008;36:1123-1131.
Summary: An arthroscopic rotator interval closure after posterior capsulolabral repair does not improve posterior stability or inferior stability but does improve anterior stability. Arthroscopic rotator interval closure significantly decreases external rotation at both neutral and abducted arm position.
Nho SJ, et al. Bioabsorbable anchors in glenohumeral shoulder surgery. Arthroscopy . 2009;25:788-793.
Summary: Metallic anchors have reported problems of implant loosening, migration, and chondral injury and have been largely replaced by bioabsorbable suture anchors, which may fail by implant breakage or premature degradation. Newer materials, such as polyetheretherketone and biocomposites, may address concerns of biocompatibility and material strength.
Provencher MT, et al. A biomechanical analysis of capsular plication versus anchor repair of the shoulder: Can the labrum be used as a suture anchor. Arthroscopy . 2008;24:210-216.
Summary: An intact posteroinferior or anteroinferior glenoid labrum provides fixation strength similar to a glenoid anchor but will show greater labral displacement (up to 1.5 mm) in load to failure testing. There were no strength differences between the anteroinferior and posteroinferior labrum.
Swan KGJr, et al. Arthroscopic suture material and knot type: An updated biomechanical analysis. Am J Sports Med . 2009;37:1578-1585.
Summary: The polyblend sutures (FiberWire, ForceFiber, MaxBraid) were stronger than braided polyester sutures (Ethibond, Ticron). Pure ultra-high molecular weight polyethylene (UHMWPE) sutures were stronger than those containing blends of UHMWPE and other materials. The surgeon’s and SMC knots were stronger than the Duncan loop and Roeder knot.
Section 2
Anterior Instability
CHAPTER 6 Findings and pathology associated with anterior shoulder instability

R. Michael Greiwe, MD, William N. Levine, MD

Key points

The shoulder is the most commonly dislocated joint in the body.
The inferior glenohumeral ligament (IGHL) is the most important capsular stabilizer of the glenohumeral joint (anterior band for anterior stability; posterior band for posterior stability).
The Bankart lesion (tear of the anterior capsulolabral structures off the glenoid) is present after nearly all anterior instability injuries and can be soft tissue only (labral tear with capsular stretch), bony (bony Bankart or anterior glenoid “fracture”), or a combination thereof.
The anterior labral periosteal sleeve avulsion (ALPSA) represents a labrum that has torn off the glenoid and healed medially down the neck.
The humeral avulsion of the glenohumeral ligament (HAGL) is a rarer variant of instability pathology in which the capsule is torn off the humerus.
The glenolabral articular disruption (GLAD) lesion represents an injury to the articular surface of the glenoid, usually after a recurrent instability event.
Bony injury is common in recurrent anterior shoulder instability, including injuries to the glenoid, humeral head (Hill-Sachs), or both.

Introduction
The shoulder is the most commonly dislocated joint in the human body, most often in the anterior direction. Depending on arm position, humeral head version, vector of force being imparted on the shoulder, and the time with which the force is delivered, an injury will occur to some or all of the anterior shoulder structures. These include the bone and surrounding cartilage, the labrum, capsule, glenohumeral ligaments, and posterior humeral head. Arthroscopy has advanced our understanding of the anatomy and pathologic findings following shoulder dislocations.
The shoulder provides the greatest range of motion of all the joints in the body. As such, it has an amazing capacity to dislocate, with the overall population incidence of 1.7%. 1 Younger patients appear to have more recurrent dislocations than older patients, and patients younger than 20, may have a chance of recurrence as high as 90%. 2 Unfortunately, after shoulder dislocation, injuries occur to the surrounding ligaments, labrum, capsule, and osteochondral surfaces, leading Hovelius et al to find moderate to severe arthritis in 26% of patients treated nonoperatively at 25 years. 3 In this chapter, we discuss the radiographic and arthroscopic findings associated with anterior instability of the shoulder.

Anatomy and biomechanics
Figure 6-1 , A demonstrates the anatomic restraints to anterior shoulder dislocation. At the periphery of the glenoid, the fibrocartilaginous labrum, and long head of the biceps deepen the socket and provide additional stability. A study by Halder et al demonstrated that resection of the glenoid labrum resulted in diminished stability to the glenohumeral joint via the concavity-compression mechanism. 4 The capsule is a thin layer of fibrous tissue that contains thickenings known as the glenohumeral ligaments. The rotator interval is a triangular area of tissue whose borders are the supraspinatus anteriorly and the subscapularis inferiorly. It contains two important ligaments: the coracohumeral ligament (CHL) and the superior glenohumeral ligament (SGHL). The stronger CHL proceeds in a distal-lateral direction from the base of the coracoid, inserting on the greater and lesser tuberosities. The coracohumeral ligament contains two layers as it splits to envelop the biceps tendon and eventually proceeds to its lateral insertion site. 5 , 6

FIGURE 6-1 A, Schematic representation of the glenohumeral capsule and ligaments. B, Arthroscopic view of the middle glenohumeral ligament (MGHL) passing perpendicularly (right shoulder, beach chair position; posterior viewing portal). C, Arthroscopic view of the inferior glenohumeral ligament (IGHL) (right shoulder, beach chair position; posterior viewing portal). D, Sagittal view of the glenohumeral ligaments. E, Graphic representation of anterior ligaments of the shoulder complex.
( B and C courtesy of Center for Shoulder, Elbow and Sports Medicine, Columbia University. D from Reider B, et al: Operative techniques: Sports medicine surgery, Philadelphia, 2010, Saunders Elsevier.)
The SGHL originates from the 1 o’clock position at the supraglenoid tubercle just anterior to the biceps tendon and inserts at the tip of the greater tuberosity. 6 The SGHL and joint capsule make up the deep layer of the medial rotator interval, and the superficial CHL makes up the more superficial layer. The functions of the CHL and SGHL are threefold: to provide a sling for the biceps, to limit external rotation when the arm is at the side, and to resist inferior translation of the arm in adduction. While the CHL is a consistent finding, the SGHL is absent 6% of the time. 7
The middle glenohumeral ligament (MGHL) has more anatomic variation than all of the glenohumeral ligaments. Like the SGHL, it originates from the supraglenoid tubercle. Its point of origin, however, is slightly more variable than the SGHL, and can originate as far as 3 o’clock on the glenoid rim. 6 Some fibers of the MGHL insert on the subscapularis muscle approximately 2 cm medial to the muscle’s insertion. 8 The MGHL may be wide and thin or cordlike, and can have varying degrees of confluence with the inferior glenohumeral ligament (IGHL) ( Fig. 6-1 , B ). The function of the MGHL is to limit external rotation of the arm with the arm in 45 degrees of abduction. The MGHL is a variable structure and can present between 65% and 85% of the time. 6 , 7
The IGHL is the most important stabilizer of the glenohumeral joint ( Fig. 6-1 , C ). The anterior band is the thickest and strongest of all of the capsular thickenings in the shoulder. In a study by Bigliani et al, the stress at failure of the IGHL, which is commonly injured in an anterior shoulder dislocation, is 5.5 MPa. 9 The IGHL originates from the 2 o’clock to 5 o’clock position on the glenoid and labrum. 7 The posterior band takes its origin between the 7 o’clock and 9 o’clock position. The anterior band is almost always present, but the posterior band is only present 60% of the time. The anterior IGHL serves as the primary static restraint to anterior instability at 90 degrees of abduction.
Because of its direct connection to the superior labrum, the long head of the biceps also may play a role in stabilizing the glenohumeral joint. A study by Rodosky et al showed that in late cocking, the long head of the biceps was found to contribute to the torsional stability of the humerus. Further, after sectioning of the long head of the biceps, the anterior/inferior structures demonstrated more strain. 10 Loading of the biceps also demonstrates decreased anterior/posterior translation of the humerus. 11 Therefore, it is clear that the long head of the biceps also plays a role in anterior stability.

Anatomic variants
Anatomic variants in the shoulder are common and must be recognized to prevent inadvertent repair of normal structures. One of the anatomic variants commonly found is the sublabral foramen, or sublabral hole, occurring in 12% of patients. 12 A sublabral foramen occurs between the 9 and 12 o’clock positions (left shoulder) and must be distinguished from an anterosuperior labral tear. Typically, it can be recognized by its smooth transition from labrum to foramen and the absence of any trauma to the adjacent labrum, cartilage, or capsule ( Fig. 6-2 ). A cordlike MGHL is found in 9% of patients and commonly is associated with a sublabral foramen ( Fig. 6-3 ). Finally, a less frequently occurring anatomic variant is the Buford complex, found in 1.5% of shoulders. Williams et al first described this variant as a cordlike MGHL found concurrently with an absent anterosuperior labrum. Failure to recognize any of these normal anatomic variants will lead to inappropriate surgical repair that can result in pain and loss of external rotation. 12

FIGURE 6-2 A, A sublabral foramen is demonstrated (double arrow) ; note the smooth border of the adjacent tissue and no evidence of trauma (left shoulder, beach chair position; posterior viewing portal). B, Example of a sublabral foramen, a normal anatomic variant. C, MRI-arthrogram (MRA) of a sublabral foramen. Note that this is not an anterior labral tear, but a normal variant.
( A courtesy of Center for Shoulder, Elbow and Sports Medicine, Columbia University. B from Williams SM, et al: The Buford complex—the “cord-like” middle glenohumeral ligament and absent centrosuperior labrum: A normal anatomic capsulolabral variant. Arthroscopy 10:244–245, 1994.)

FIGURE 6-3 Posterior viewing portal of a cordlike MGHL (left shoulder, lateral decubitus position).
(Courtesy of Center for Shoulder, Elbow and Sports Medicine, Columbia University.)

Lesions of the glenoid labrum and ligamentous attachments

Bankart lesion
The Bankart lesion is an avulsion of the anterior labroligamentous structures from the anterior glenoid rim. Bankart described it as the “lesion of necessity” in anterior shoulder instability and believed that it occurred in 100% of all dislocations. 13 Modern studies estimate that approximately 90% of all anterior dislocations have Bankart lesions. 14 The anterior scapular periosteum is disrupted, and the labrum and attached ligaments are typically found anterior to the glenoid rim. Therefore, the anterior band of the inferior glenohumeral ligament or middle glenohumeral ligament cannot perform their stabilizing functions at the end ranges of motion. In addition, the labrum does not function to deepen or stabilize the glenoid socket. With the labrum removed, the force required to translate the shoulder anteriorly is reduced by 50%. 15
After appropriate history and physical examination, magnetic resonance imaging (MRI) with intra-articular gadolinium is often obtained to confirm the pathologic findings. The Bankart lesion is usually found on the axial cut of the MRI, in the anteroinferior aspect of the glenoid. Gadolinium is visualized between the anterior labrum and glenoid ( Fig. 6-4 , A ).

FIGURE 6-4 A, Axial MR arthrogram demonstrating an anterior labral tear. Note fluid interposed between anterior labrum and glenoid (arrow). B, Anterosuperior viewing portal of a detached anteroinferior labrum ( double arrowhead indicates separation of labrum from glenoid) (right shoulder, lateral decubitus position). C, Depiction of typical Bankart tear. D, Coronal view of typical Bankart tear.
( B courtesy of Center for Shoulder, Elbow, and Sports Medicine, Columbia University. C from Lee DH, et al: Operative techniques: Shoulder and elbow surgery, Philadelphia, 2011, Saunders Elsevier, Fig. 12-15, B . D from Reider B, et al: Operative techniques: Sports medicine surgery , Philadelphia, 2010, Saunders Elsevier.)
During arthroscopic evaluation, an abnormal separation between the labrum and glenoid is often present ( Fig. 6-4 , B ). There will occasionally be hemorrhage signifying injury, but because of the poor vascularity of the glenoid, this is not a reliable finding. A probe can be used to identify the labral tear, confirming the preoperative examination and imaging studies.

Anterior labroligamentous periosteal sleeve avulsion (ALPSA)
Neviaser first described the ALPSA lesion in 1993. 15a The labroligamentous complex heals medially on the glenoid neck allowing for recurrent anterior instability due to the incompetent anterior IGHL. In contrast, the Bankart lesion contains a rupture of the scapular periosteum, and the injured tissue stays at the level of the glenoid surface. Recent reports have suggested that ALPSA lesions do not usually occur with first time dislocations. Habermeyer et al described a “time-dependent” and “recurrence-dependent” etiology for the evolution of the ALPSA lesion. 16 Another recent study suggested that almost all ALPSA lesions were found to exist in shoulders with chronic dislocations. 17
The ALPSA lesion is best identified with a contrast-enhanced MRI ( Fig. 6-5 ). After an acute injury, the anterior glenoid periosteum is stripped down to the neck of the glenoid, and contrast fills this space. In a chronic situation, the anterior scapular periosteum and labroligamentous structures are found in a ball or heap on the scapular neck.

FIGURE 6-5 A, Axial MRA demonstrating an ALPSA lesion (arrow). B, Axial MRA depicting another example of an ALPSA tear. C, ALPSA tear. D, ALPSA tear, coronal view.
( A courtesy of Center for Shoulder, Elbow and Sports Medicine, Columbia University. C from Lee DH, et al: Operative techniques: Shoulder and elbow surgery, Philadelphia, 2011, Saunders Elsevier. D from Reider B, et al: Operative techniques: Sports medicine surgery, Philadelphia, 2010, Saunders Elsevier.)
Arthroscopically, an ALPSA lesion can be difficult to identify from the posterior viewing portal ( Fig. 6-6 , A ). Usually, the labroligamentous complex has healed medially and cannot be seen with an apparent loss of labral tissue. However, the lesion can be best visualized from the anterosuperior portal ( Fig. 6-6 , B ). This position gives a view down the anterior glenoid face and allows identification of the medially displaced and healed labroligamentous complex. In these situations, this tissue must be elevated off of the scapular neck and brought back into anatomic position on the glenoid face.

FIGURE 6-6 A, Posterior viewing portal of an ALPSA lesion. Note the apparent “absent labrum” (left shoulder, lateral decubitus position). B, Anterosuperior viewing portal of same shoulder. Note the ALPSA lesion (small arrowhead) and the glenoid articular cartilage (arrow) (left shoulder, lateral decubitus position).
( A and B courtesy of Center for Shoulder, Elbow and Sports Medicine, Columbia University.)

Glenolabral articular disruption (GLAD)
The GLAD lesion was also described by Neviaser in 1993. 17a This lesion typically occurs following a forced adduction of the externally rotated and abducted arm and is a shear injury to the articular cartilage and glenoid labrum. A study by Sanders et al found six patients with GLAD lesions diagnosed by magnetic resonance (MR) arthrography. 17b Five of the six had a history consistent with an impaction injury associated with an abducted and externally rotated arm. Four then underwent arthroscopy where the GLAD lesion was identified.
Lesions are best visualized using MR arthrography with a cartilage definition sequence such as fast spin-echo. These sequences show a loss of articular cartilage adjacent to a labral defect.
Arthroscopic findings will suggest either a flap tear of cartilage tissue or a loss of articular cartilage ( Fig. 6-7 ). Loose bodies may or may not be present in the shoulder.

FIGURE 6-7 A, Posterior viewing portal demonstrating a GLAD lesion (glenolabral articular defect) (right shoulder, lateral decubitus position). B , Example of GLAD lesions (white arrows).
( A courtesy of Center for Shoulder, Elbow and Sports Medicine, Columbia University. B provided courtesy of Matthew T. Provencher, MD, San Diego, CA. C from Reider B, et al: Operative techniques: Sports medicine surgery, Philadelphia, 2010, Saunders Elsevier.)

Bony bankart
The bony Bankart injury results from an anterior dislocation that causes a fracture of the anterior-inferior glenoid in varying sizes. It is unclear whether the humeral anatomy, arm position, or timing and direction of applied force cause this pattern of injury, rather than a labral injury. While the bony architecture of the glenoid is small, it is highly congruent. 18 A slight injury to the shallow anterior bony glenoid allows the humeral head to easily sublux anteriorly.
Hintermann et al prospectively evaluated the arthroscopic findings of 212 consecutive arthroscopies in patients with a history of shoulder dislocation. The authors found a 30% rate of bony Bankart lesions in this series. 14 Burkart, who has emphasized the “inverted pear glenoid” to denote loss of anteroinferior glenoid bone, found that 61% of typical arthroscopic methods of fixation were doomed to failure when the patient had an “inverted pear” shaped glenoid. 19
The bony Bankart lesion occasionally can be seen on plain radiography. An instability series consisting of true anteroposterior (AP) views in neutral, internal and external rotation, a scapular Y view, and axillary views are obtained. Sometimes, the Stryker notch and West Point views can provide additional information. A recent study, however, suggested that 60% of bony lesions were not found on plain radiographs alone. 20 The best diagnostic tool for visualizing glenoid bone defects is a computed tomography (CT) scan ( Fig. 6-8 ). When necessary, a three-dimensional (3-D) CT reconstruction can show the inverted pear lesion, so that adequate preoperative planning can be made.

FIGURE 6-8 Axial CT scan demonstrating a large anteroinferior bony Bankart lesion.
(Courtesy of Center for Shoulder, Elbow and Sports Medicine, Columbia University).
During arthroscopic evaluation of a glenoid bone defect, it is important to view from the anterosuperior portal. This view allows visualization of a possible “inverted pear” glenoid and may allow visualization of the fractured bone that has displaced anteriorly. The common failure to diagnose this entity and subsequent higher recurrence rates underscore the importance of adequate preoperative imaging before surgery. 19 , 21

Humeral avulsion of glenohumeral ligament (HAGL)
While avulsion of the anterior inferior glenohumeral ligament from the glenoid is common, humeral-sided avulsions also can occur following anterior shoulder dislocations. Bach et al first described humeral detachment of the glenohumeral ligaments in 1988. 22 In a classic biomechanical study of the inferior glenohumeral ligament, humeral avulsion of the ligaments was noted in 25% of the specimens. 22a Wolf et al later coined the term “HAGL” (Humeral Avulsion of the Glenohumeral Ligaments) in 1995 and noted an incidence of 1% to 9% of shoulders following anterior dislocations. 23
In patients with documented anterior instability, a HAGL lesion should be ruled out because this may have implications for preoperative planning; for example, many surgeons will choose to treat HAGL lesions with open surgery if it is diagnosed. This lesion can be diagnosed on a T2 weighted coronal image MRI with gadolinium enhancement ( Fig. 6-9 A ).

FIGURE 6-9 A, Coronal oblique MR arthrogram demonstrating detachment of the capsule from the humerus (a humeral avulsion of the glenohumeral ligament [HAGL] lesion). B, Arthroscopic view of a HAGL lesion (lateral decubitus position). C, HAGL tear.
( A courtesy of Matthew T. Provencher, MD, San Diego, CA. B courtesy of Matthew Provencher, MD, San Diego, CA. C From Reider B, et al: Operative techniques: Sports medicine surgery, Philadelphia, 2010, Saunders Elsevier.)
At the time of arthroscopy it is critical to thoroughly evaluate the entire capsule and ligamentous complex ( Fig. 6-9 , B ). If a HAGL lesion is identified, it must be treated or the failure rate for arthroscopic Bankart repair is much higher.

Superior labral anterior and posterior tears
Although a superior labral anterior and posterior (SLAP) tear is not a primary diagnosis of anterior instability, these lesions often are found concurrently in patients following dislocations. In Hintermann et al’s study of 212 patients treated arthroscopically, a 7% incidence of SLAP tears was identified. 14
MRI with intra-articular gadolinium is the preferred imaging study for confirming the diagnosis. The most superior cuts on the axial images will demonstrate contrast between the glenoid and the superior labrum ( Fig. 6-10 , A ). Coronal oblique views likewise demonstrate dye between the labrum and the glenoid ( Fig. 6-10 , B ).

FIGURE 6-10 A, Axial MRI demonstrating SLAP tear. Note dye interposed between superior glenoid and labrum (arrow). B, Coronal oblique MRI demonstrating SLAP tear. Note dye interposed between superior glenoid and labrum (arrow). C, Arthroscopic posterior viewing portal of a complex SLAP tear (type V) associated with an anterior labral tear. Note the probe on the inferiorly dislocated superior labrum (right shoulder, lateral decubitus position).
( A to C courtesy of Center for Shoulder, Elbow and Sports Medicine, Columbia University.)
At the time of arthroscopy, SLAP tears can be identified in conjunction with other lesions in the shoulder, including labral tears, capsular tears, rotator cuff tears, and ligament avulsions. These lesions have been classified by Snyder as types 1, 2, 3, and 4. 24 Maffet et al further classified these lesions as types 5 to 8. 25 SLAP tears associated with anterior labral tears have been classified as type V lesions ( Fig. 6-10 , C ). Type 2 and 4 lesions render the biceps anchor unstable and typically require arthroscopic stabilization. In older patients or in younger patients who have failed attempted repair, a biceps tenodesis may be an appropriate alternative to consider.

Capsular lesions

Capsular injury
Spatschil et al arthroscopically evaluated 303 patients with posttraumatic anterior-inferior instability for capsular injury. Isolated capsular injuries are rare accounting for only 11% of all injury patterns. However, capsular injuries in association with other pathology are extremely common, and injuries to the IGHL or MGHL were found to occur in 60% and 50% of all recurrent and primary dislocations, respectively. Not surprisingly, capsular injuries were found to be more frequent following recurrent dislocations. 26

Thermal capsular damage
Thermal capsulorrhaphy was developed in an attempt to arthroscopically modify the collagen triple helix by shortening it and decreasing the capsular volume. However, initial widespread enthusiasm was tempered by reports of clinical failures and unforeseen complications. D’Alessandro et al reported a prospective study and demonstrated a 37% unsatisfactory rate. 27 Other studies have shown similar failure rates (36% to 50%). 28 - 30
One potential cause for the high failure rate is the thermal injury that is imparted to the capsule. A recent histologic study confirmed that histologic changes occur up to 16 months following thermal capsulorrhaphy. Upon gross inspection, 71% of the cases had thin and attenuated capsules. 31
In patients who have failed prior arthroscopic thermal procedures, planning for possible capsular insufficiency is critical to enhance success. If the capsule is so attenuated (or absent), then an open reconstruction with allograft reinforcement may become necessary.

Humeral lesions

Hill-sachs defect
A humeral-sided bone defect is a common finding after shoulder dislocation and was first described by Hill and Sachs in their classic article in 1940. They termed it a “grooved defect” of the humeral head when the relatively softer posterolateral bone of the humeral head is impacted against the more dense bone of the glenoid. 32
The incidence of Hill-Sachs defects after a primary shoulder dislocation is between 47% and 80%. In recurrent instability, the lesion is found even more frequently. 26 , 33 An axillary radiograph, AP in internal rotation, or a Stryker notch view (axillary radiograph obtained in 45 degrees of internal rotation) are the best initial studies to obtain to determine the size and location of a Hill-Sachs defect. However, bony lesions of the humeral head are probably best identified on CT scan.
The Hill-Sachs defect must be differentiated arthroscopically from the bare area. The bare area is an area of dense subchondral bone adjacent to the footprint of the infraspinatus tendon. A Hill-Sachs defect is an area of impacted bone adjacent to an area of normal cartilage. The bone will appear impacted and may present as exposed cancellous bone with hemorrhage, or in more chronic cases with an impacted area of fibrocartilage scar. Occasionally, when the Hill-Sachs lesion is large enough, the lesion can be seen to “engage” the anterior rim of the glenoid in the position of abduction and external rotation. In these cases, surgery is often necessary to prevent chronic subluxation or dislocation.

Physical examination (see chapter videos)

• Apprehension test ( VIDEO 6-1 ): The patient is in a supine position and the arm is placed in 90 degrees abduction and 90 degrees of external rotation. A positive test for anterior instability occurs if the patient experiences “apprehension.” On the other hand, if the patient experiences “pain,” especially if the shoulder is extended as well, this is more likely positive for “internal impingement.”


Pearl
Make sure to avoid hyperextension of the shoulder to avoid crossover with internal impingement.
• Relocation test ( VIDEO 6-2 ): The patient is in a supine position and a posteriorly directed force is applied to the shoulder after a positive apprehension test has been documented. The patient will experience decreased sensation of subluxation.
• Anterior release test ( VIDEO 6-3 ): This is a combination of the relocation and apprehension tests. It is performed in the supine position as well. The examiner applies a posteriorly directed force on the humerus as the arm is brought in to 90 degrees abduction and 90 degrees external rotation. When the shoulder reaches the typical apprehension position the examiner removes the hand, and the patient will experience subluxation and a positive anterior release test.
• Active compression test ( VIDEO 6-4 ): This is an upright examination. The arm is placed in 90 degrees forward flexion, 15 degrees adduction and then maximal internal rotation (thumb down) and the patient is asked to resist downward pressure from examiner. A “positive” test is one in which the patient experiences “deep pain” suggestive of a SLAP tear. The pain will be decreased or eliminated when the maneuver is repeated with the arm maximally externally rotated (thumb up). If the patient experiences pain that is “superficial” this will often represent AC joint-related symptoms.

Pearls and Pitfalls
Be wary of this test if it is positive in association with many other tests (false positive). However, if it is the only positive test (or one of just a few) it seems to be more reliable.
• Generalized ligamentous laxity: patients with anterior instability should be examined for this by noting thumb to forearm apposition, elbow recurvatum, and metacarpophalangeal (MCP) hyperextension.

Imaging evaluation

• Plain Films
• True AP (Grashey view): This is a critical view designed to show the glenohumeral joint in profile to evaluate the joint space and the normal relationship of the humeral head and the glenoid.
• Axillary: This is essential to rule out dislocation (anterior or posterior). This view can also demonstrate bony deficiency of the anteroinferior glenoid or the posterolateral humeral head (Hill-Sachs lesion).
• Scapular lateral ( Y view): This is the third view obtained routinely and can also help demonstrate anterior or posterior instability.
• AP in internal rotation: This view is helpful for demonstrating the Hill-Sachs lesion (posterolateral impression defect of the humeral head).
• MRI Arthrography
• Intra-articular gadolinium is our preferred imaging study to demonstrate labral tears. As previously indicated, there are a number of normal anatomic variants, and these need to be differentiated from pathologic labral tears.
• The coronal oblique view is the best view to identify SLAP tears.
• The axial view demonstrates anterior and posterior labral tears.
• CT
• CT is indicated for suspected bony deficiencies (glenoid and humeral head).
• A 3-D CT reconstruction is typically ordered as well in these cases to better identify and quantify the bony deficiency.
• The best CT scan to measure glenoid bone loss is a 3D reconstruction of the glenoid with the humeral head digitally subtracted ( enface view).

Conclusions
Shoulder arthroscopy has dramatically improved our ability to identify the pathologic tissues of the labrum, capsule, and bone. A thorough understanding of the normal glenohumeral anatomy and recognized anatomic variants is critical to properly diagnose and treat patients with anterior shoulder instability. Finally, familiarity with these variants will assist in eliminating their inappropriate fixation, which typically will lead to loss of motion and functional deficits.


VIDEOS
Videos available at www.expertconsult.com

Video 6-1 Apprehension maneuver
Examiner places patient’s involved shoulder into 90 degrees abduction and 90 degrees of external rotation. A positive test is considered if the patient experiences a sense of “apprehension” that the shoulder will sublux or dislocate.

Video 6-2 Relocation maneuver
Examiner places a posteriorly directed force on the anteriorly subluxed humeral head, thereby eliminating the “apprehension.”

Video 6-3 Anterior release test
This test combines the apprehension and relocation into one maneuver. The examiner applies a relocation force to the humeral head while the arm is brought into an apprehension position (90/90) and then removes the hand, allowing the humeral head to sublux and reproduce the symptoms of anterior instability.

Video 6-4 Active compression test
The examiner places the patient ’s arm in 90 degrees of forward flexion, 15 degrees of adduction and maximal internal rotation (thumb down) and asks the patient to resist downward force. The maneuver is repeated with the thumb up. A positive test for a SLAP tear is one in which the patient describes “deep pain” in the thumb-down position that is decreased or eliminated with the thumb-up position. A positive test for acromioclavicular (AC) joint pathology is one in which the patient describes pain over the AC joint.

References

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2. Arciero RA, et al. Arthroscopic Bankart repair versus nonoperative treatment for acute, initial anterior shoulder dislocations. Am J Sports Med . 1994;22(5):589-594.
3. Hovelius L, et al. Arthropathy after primary anterior shoulder dislocation—223 shoulders prospectively followed up for twenty-five years. J Shoulder Elbow Surg . 2009;18(3):339-347.
4. Halder AM, et al. Effects of the glenoid labrum and glenohumeral abduction on stability of the shoulder joint through concavity-compression: An in vitro study. J Bone Joint Surg Am . 2001;83-A(7):1062-1069.
5. Jost B, et al. Anatomy and functional aspects of the rotator interval. J Shoulder Elbow Surg . 2000;9(4):336-341.
6. Steinbeck J, et al. The anatomy of the glenohumeral ligamentous complex and its contribution to anterior shoulder stability. J Shoulder Elbow Surg . 1998;7(2):122-126.
7. Ide JS, et al. Normal variations of the glenohumeral ligament complex: An anatomic study for arthroscopic Bankart repair. Arthroscopy . 2004;20(2):164-168.
8. Burkart AC, et al. Anatomy and function of the glenohumeral ligaments in anterior shoulder instability. Clin Orthop Relat Res . 2002;400:32-39.
9. Bigliani LU, et al. Tensile properties of the inferior glenohumeral ligament. J Orthop Res . 1992;10(2):187-197.
10. Rodosky MW, et al. The role of the long head of the biceps muscle and superior glenoid labrum in anterior stability of the shoulder. Am J Sports Med . 1994;22(1):121-130.
11. Itoi E, et al. Dynamic anterior stabilisers of the shoulder with the arm in abduction. J Bone Joint Surg Br . 1994;76(5):834-836.
12. Williams MM, et al. The Buford complex—the “cord-like” middle glenohumeral ligament and absent anterosuperior labrum complex: A normal anatomic capsulolabral variant. Arthroscopy . 1994;10(3):241-247.
13. Bankart ASB. The pathology and treatment of recurrent dislocation of the shoulder. Br J Surg . 1938;26:23-29.
14. Hintermann B, et al. Arthroscopic findings after shoulder dislocation. Am J Sports Med . 1995;23(5):545-551.
15. Matsen FA, et al. Mechanics of glenohumeral instability. Clin Sports Med . 1991;10(4):783-788.
15a. Neviaser TJ. The anterior labroligamentous periosteal sleeve avulsion lesion: a cause of anterior instability of the shoulder. Arthroscopy . 1993;9(1):17-21.
16. Habermeyer P, et al. Evolution of lesions of the labrum-ligament complex in posttraumatic anterior shoulder instability: A prospective study. J Shoulder Elbow Surg . 1999;8(1):66-74.
17. Yiannakopoulos CK, et al. A comparison of the spectrum of intra-articular lesions in acute and chronic anterior shoulder instability. Arthroscopy . 2007;23(9):985-990.
17a. Neviaser TJ. The GLAD lesion: another cause of anterior shoulder pain. Arthroscopy . 1993;9(1):22-23.
17b. Sanders TG, et al. The glenolabral articular disruption lesion: MR arthrography with arthroscopic correlation. AJR AM J Roentgenol . 1999;172(1):171-175.
18. Soslowsky LJ, et al. Articular geometry of the glenohumeral joint. Clin Orthop Relat Res . 1992;285:181-190.
19. Burkhart SS, et al. Traumatic glenohumeral bone defects and their relationship to failure of arthroscopic Bankart repairs: Significance of the inverted-pear glenoid and the humeral engaging Hill-Sachs lesion. Arthroscopy . 2000;16(7):677-694.
20. Bushnell BD, et al. The bony apprehension test for instability of the shoulder . San Francisco, CA: Annual Meeting of the American Academy of Orthopaedic Surgeons; 2008.
21. Tauber M, et al. Reasons for failure after surgical repair of anterior shoulder instability. J Shoulder Elbow Surg . 2004;13(3):279-285.
22. Bach BR, et al. Disruption of the lateral capsule of the shoulder. A cause of recurrent dislocation. J Bone Joint Surg Br . 1988;70(2):274-276.
22a. Bigliani LU, et al. Tensile properties of the inferior glenohumeral ligament. J Orthop Res . 1992;10(2):187-197.
23. Wolf EM, et al. Humeral avulsion of glenohumeral ligaments as a cause of anterior shoulder instability. Arthroscopy . 1995;11(5):600-607.
24. Snyder SJ, et al. SLAP lesions of the shoulder. Arthroscopy . 1990;6(4):274-279.
25. Maffet MW, et al. Superior labrum-biceps tendon complex lesions of the shoulder. Am J Sports Med . 1995;23(1):93-98.
26. Spatschil A, et al. Posttraumatic anterior-inferior instability of the shoulder: Arthroscopic findings and clinical correlations. Arch Orthop Trauma Surg . 2006;126(4):217-222.
27. D’Alessandro DF, et al. Prospective evaluation of thermal capsulorrhaphy for shoulder instability: Indications and results, two- to five-year follow-up. Am J Sports Med . 2004;32(1):21-33.
28. Miniaci A, et al. Thermal capsular shrinkage for treatment of multidirectional instability of the shoulder. J Bone Joint Surg Am . 2003;85-A(12):2283-2287.
29. Levy O, et al. Thermal capsular shrinkage for shoulder instability. Mid-term longitudinal outcome study. J Bone Joint Surg Br . 2001;83(5):640-645.
30. Frostick SP, et al. Arthroscopic capsular shrinkage of the shoulder for the treatment of patients with multidirectional instability: Minimum 2-year follow-up. Arthroscopy . 2003;19(3):227-233.
31. McFarland EG, et al. Histologic evaluation of the shoulder capsule in normal shoulders, unstable shoulders, and after failed thermal capsulorrhaphy. Am J Sports Med . 2002;30(5):636-642.
32. Hill HA, et al. The grooved defect of the humeral head. A frequently unrecognized complication of dislocation of the shoulder joint. Radiology . 1940;35:690-700.
33. Bushnell BD, et al. Bony instability of the shoulder. Arthroscopy . 2008;24(9):1061-1073.
CHAPTER 7 Clinical history and physical examination

Edward G. McFarland, MD, Juan Garzon-Muvdi, MD, Steve A. Petersen, MD

Key points

The position of the patient’s arm at the time of an instability episode is critical for determining the direction of instability.
The anterior apprehension test and relocation tests, when apprehension is used as the criterion for diagnosis, are very accurate.
Any instability test (anterior or posterior) for which pain is the criterion for instability should not be taken as a diagnostic sign of instability.
Shoulder laxity testing can help in the evaluation of shoulder instability if it reproduces symptoms of instability.
What constitutes inferior glenohumeral instability has not been adequately established.

Introduction
The shoulder joint has been found by many providers to be difficult to examine, especially when it comes to making the diagnosis of instability. The good news is that most cases of traumatic anterior shoulder instability can be diagnosed with a good history and physical examination. However, posterior instability and patients with instability in more than one direction can create a diagnostic challenge. Similarly, a substantial number of patients can present with lesser degrees of shoulder instability in which they have a sense of looseness in the shoulder but cannot localize the direction of their symptoms. Such patients may or may not complain of symptoms only with certain shoulder motions. Because the shoulder has a wide range of normal laxities, whether such patients have a form of hyperlaxity or whether their condition should be called multidirectional instability is controversial; the challenge is to determine if the laxity is pathologic.
This chapter highlights the most reliable history and physical examination methods for evaluating patients with these various forms of instability, addresses the controversy over the role of instability in creating shoulder pain in the overhead athlete and how to interpret the examinations in such patients, and discusses the challenge of diagnosing multidirectional instability.

History
When evaluating patients with shoulder instability, patient history plays an important role in reliably determining the diagnosis. Patients should be asked about having any neurologic symptoms (such as paresthesias or weakness) because they are not typically caused by shoulder abnormalities and may indicate a neurologic cause of their symptoms. Patients also should be asked about coldness or swelling in the extremity because such symptoms may indicate a vascular cause, such as an exertional deep venous thrombosis or thoracic outlet syndrome.
Then questions should be directed to the mechanism of injury to the shoulder, the symptoms at the time of injury, the effect of the injury on the ability to perform activities of daily living, and if there is a history of any joint instability or connective tissue disorders in the individual or a family member. Patient demographic factors also play an important role in the choice of treatment plan.
The mechanism of injury refers to the activity the individual was performing at the time of the incident, the position of the arm at the time of the injury, and the direction of force on the arm. Traumatic anterior shoulder instability typically occurs when the arm is placed in an abducted and externally rotated position with the arm in extension, such as throwing a ball or reaching behind from the front to the back seat of a car. Posterior shoulder instability typically occurs when an axial load is applied to the arm when it is in front of the body, such as an offensive lineman in football blocking with his arms outstretched in front, but it can also occur when the leading arm comes across the body into abduction, such as in the follow-through of a golf swing or when a baseball player is batting. True inferior instability, or luxatio erecta, occurs when the arm is jerked with high force from an adducted position to an abducted position in the plane of the body, resulting in the arm being stuck at approximately 90 degrees of abduction. This arm position after a dislocation distinguishes it from anterior and posterior instability, in which the arm is typically closer to the side, at approximately 20 degrees to 30 degrees of elevation.
The symptoms at the time of injury are important because they can indicate the degree of the injury. Patients with traumatic shoulder instability typically have fairly severe pain until the shoulder is reduced. Patients with dislocations can usually tell the practitioner which way the humeral head was dislocated. Patients with traumatic subluxation may have severe pain but may not be able to distinguish the direction of instability. Usually patients with a dislocation or subluxation cannot continue with their sport or activity after the event, which is an indicator to the clinician of the severity of the injury.
Patients with recurrent shoulder instability experience dislocation or subluxation that affects their function and ability to participate in sports and may interfere with their activities of daily living. Therefore, determining the extent of disability is an important part of the decision-making process. The clinician also should elicit information about familial laxity and connective tissue disorders such as Ehlers-Danlos syndrome or Marfan syndrome because such patients are known to have dislocations of multiple joints and tend to have frequent recurrences.
Other demographic factors that may help determine treatment are patient age, whether the instability began with insidious onset or from a specific injury, whether the affected side is the dominant or nondominant extremity, whether the patient has concomitant injuries, and the patient’s sports of choice and aspirations for those sports.


Pearls

The mechanism and arm position at the time of injury are important clues to the direction of the shoulder instability.
The frequency of dislocations or subluxations is important information about the amount of disability the patient is experiencing.
Subluxations without trauma may suggest an underlying connective tissue disorder.

The basic examination
There are several basic portions of the physical examination that should be part of every examination. First, both shoulders of the patient should be exposed and examined for asymmetry that may indicate more severe injuries (e.g., subluxation versus dislocation; nerve injury versus no nerve injury) or subtle muscle atrophy. A neurologic examination of both upper extremities is also helpful to rule out nerve or vessel injury associated with shoulder instabilities. Although all dermatomes, myotomes, and peripheral nerves should be tested, particular attention should be paid to the function of the axillary nerve, which is the most common nerve injured in instability episodes. However, more extensive involvement of the brachial plexus or the peripheral nerves has been reported after shoulder instability, especially after inferior dislocations (i.e., luxatio erecta).
Strength testing should be performed, specifically of the rotator cuff muscles. The supraspinatus can be tested with the arm abducted 90 degrees; the infraspinatus, with resisted external rotation with the arm at the side; and the subscapularis, with the lift-off test or belly-press test. Lag signs, such as the external rotation lag sign and the lift-off lag sign, are also helpful for patients with suspected rotator cuff injury after a dislocation. 1 Range of motion of the shoulder, including elevation, rotations at 90 degrees of elevation, external rotation with the arm at the side, and internal rotation with the arm up the back, should be assessed. Increased external rotation with the arm at the side may be helpful for diagnosing subscapularis tendon tears, but other tests more specific for testing the subscapularis tendon (e.g., the lift-off test or belly-press test) are typically more useful in making that diagnosis.
Lastly, it is often helpful to ask patients if they can reproduce their instability episodes, especially if they have indicated they could subluxate the shoulder from an early age. The ability to subluxate the shoulder over the glenoid rim intentionally with muscle activity or by positioning the arm has been called “voluntary,” “habitual,” “involuntary,” and “demonstrable” instability. Because such patients typically can reduce the shoulder subluxation themselves, measuring generalized joint hyperlaxity may be helpful to rule out such disorders as Marfan or Ehlers-Danlos syndromes.

Types of shoulder instability

Anterior shoulder instability
Anterior shoulder instability can result from traumatic or atraumatic causes. In patients who are experiencing true instability where the shoulder dislocates or subluxates, the physical examination findings are fortunately fairly accurate and can reliably make the diagnosis. However, it is important to note that these physical examination tests are most accurate when the criterion for a positive test is “apprehension” with the test and not pain alone.
For anterior shoulder instability, the time-proven examination test is the anterior apprehension test. 2 In this test, the arm is abducted, externally rotated, and extended until the patient reports apprehension that the shoulder will subluxate or dislocate ( Fig. 7-1 ). Lo et al 3 found that the position of apprehension averaged 90 degrees abduction and 83.44 degrees of external rotation. Some studies have found that the anterior apprehension test has excellent specificity (95.7% to 100%) and sensitivity (50% to 55.6%) ( Table 7-1 ). 3 , 4 If a patient has a positive test for apprehension then the likelihood ratio has been reported to be as high as 20. 4 However, if the patient has only pain with this maneuver, then the sensitivity and specificity are significantly lower 4 ; pain alone with this maneuver should not be interpreted as a sign of anterior instability (see Table 7-1 ).

FIGURE 7-1 The anterior apprehension test.

Table 7-1 Diagnostic Value of Physical Examination Tests for Anterior Shoulder Instability
A variation of the anterior apprehension test is the relocation maneuver. 5 This test is performed essentially like a supine apprehension test: the patient is positioned supine, and the arm is placed in abduction, external rotation, and extension until the patient reports apprehension that the shoulder may subluxate or dislocate. When the patient reports apprehension, the examiner places a posterior force on the humeral head from the front, thereby stabilizing the humeral head ( Fig. 7-2 ). If the patient reports that this maneuver relieves the apprehension, then the test is positive and strongly supports the diagnosis of anterior instability (likelihood ratio = 10, sensitivity = 81%, specificity = 92%). 4 However, if pain is used as the criterion for a positive test instead of apprehension, Farber et al 4 found that the sensitivity and specificity are much lower, and the likelihood ratio is only 31.13; they also found that the likelihood ratio of the relocation test is 3. 4

FIGURE 7-2 The relocation test.
(From McFarland EG : Shoulder range of motion. In Kim TK, Park HB, El Rassi G, Gill H, Keyurapan E, editors: Examination of the shoulder: The complete guide, New York, 2006, Thieme, pp 15–87.)
A third test reported to be equally sensitive and specific for anterior instability is the surprise test. 3 This test is performed exactly like a relocation test as described above except that after the humeral head has been stabilized by the examiner, the examiner then suddenly releases the stabilizing posterior force on the humeral head. This should “surprise” the patient as it recreates suddenly the forces that produce symptoms of instability. Lo et al 3 reported that this test had a sensitivity of 63.89% and a specificity of 98.91%. However, they admitted that this test should be performed with caution because the patient may be caught unaware and the shoulder might subluxate or dislocate. Therefore, we do not include this test in our examination of patients with anterior instability.
The last test for making the diagnosis of anterior shoulder instability is the use of shoulder laxity testing. Laxity of the shoulder is the measure of translation of the humeral head on the glenoid surface. A certain degree of shoulder laxity is normal because it allows the shoulder to have such a wide range of motion. However, when the laxity becomes excessive and leads to symptomatic subluxations, it is considered abnormal and is called instability.
There are basically two ways to test shoulder laxity on examination. One is by performing the anterior and posterior drawer tests ( Figs. 7-3 and 7-4 ) as described by Gerber et al. 6 These tests are performed by elevating the arm to 70 to 80 degrees and then stabilizing the scapula by creating an axial force up the humerus into the glenoid. The hands are then used to subluxate the shoulder anteriorly and posteriorly to see if the humeral head can be subluxated over the glenoid rim (see Fig. 7-2 ). The second way to measure shoulder laxity is with the load-and-shift test, 7 which is typically performed with the patient sitting. This test is performed by stabilizing the scapula and shoulder by placing one hand on the top of the shoulder and placing the second hand on the arm. The arm is held in a position of 20 degrees of abduction, 20 degrees of flexion, and in neutral, and the clinician exerts an anterior and posterior force to translate the humeral head over the glenoid rim.

FIGURE 7-3 Laxity testing using the anterior (A, B) and posterior (C, D) drawer signs.
(Parts A and C from McFarland EG : Instability and laxity. In Kim TK, Park HB, El Rassi G, Gill H, Keyurapan E, editors: Examination of the shoulder: The complete guide, New York, 2006, Thieme, pp 162–212.)

FIGURE 7-4 Laxity in the shoulder can be graded using a modified Hawkins scale.
(From McFarland EG , et al: Posterior shoulder laxity in asymptomatic athletes. Am J Sports Med 24(4): 468-471, 1996.)
Laxity of the shoulder can be measured several ways, but all involve translation of the humeral head. The first is to measure in millimeters the translation of the humeral head on the glenoid, which is difficult to accurately establish on examination. The second is to report the translation as the percentage of the humeral head diameter that translates over the glenoid. Using this second technique, the examiner would estimate that 25%, 50%, or more of the humeral head translates over the glenoid. Although this method seems logical, it has not been shown to be valid or reliable. The third is a procedure originally described by Silliman et al 7 in which the examiner reports what he or she feels when translating the humeral head over the glenoid (see Fig. 7-1 ). When performing a load-and-shift test or the drawer tests, the examiner will feel the humeral head translate over the glenoid rim and spontaneously reduce (grade II) or will not feel the humeral head translate over the rim (grade I). Grade III laxity is an uncommon finding in the office examination but occurs in approximately 5% of all patients with a diagnosis of shoulder instability who are examined under anesthesia. 8
There is a wide range of normal shoulder laxities, and the ability to subluxate the shoulder over the glenoid rim is not diagnostic of shoulder instability. In subjects who have never had symptoms of instability or pain in the shoulder, more than 50% can be subluxated over the posterior glenoid rim (grade III posterior laxity). 9 Similarly, the ability to subluxate the shoulder over the glenoid rim anteriorly or posteriorly is greater in patients under anesthesia than in the office. 8
The role of shoulder laxity testing in the examination has become better defined. 4 The usefulness in the office setting is limited by the inability of approximately 15% of patients to relax for the examination. 4 Similarly, the examiner should realize that asymmetry of shoulder laxity can occur in up to 30% of subjects who do not have shoulder instability. Consequently, it is important that the examiner (1) examine the normal and affected side, (2) attempt to subluxate the unaffected side over the glenoid rim, and (3) ask the patient if the subluxation is similar to the sensation felt when the shoulder produces symptoms. If the patient is markedly guarding the affected shoulder, subluxation of the other shoulder often results in the patient exclaiming that the feeling is similar to the one in the affected shoulder except that the event in the affected shoulder is more painful. However, the clinical use of laxity testing for traumatic anterior instability has shown that laxity testing is not as valuable as the apprehension (sensitivity = 72%, specificity = 96%, likelihood ratio = 20.22) or relocation (sensitivity = 81%, specificity = 92%, likelihood ratio = 10.35) tests; laxity testing has a sensitivity of 53%, a specificity of 85%, and a likelihood ratio of 3.57 (positive) and 0.56 (negative) for traumatic anterior instability of the shoulder. 4
Chronic, locked anterior shoulder instability is uncommon but when it does occur, it is usually seen in patients who have experienced motor vehicle accidents, seizures, or substance abuse or in those who are otherwise fully healthy. It can occasionally occur after closed or open manipulation of the shoulder under anesthesia. Patients with locked anterior dislocations present with shoulder pain, swelling, and loss of range of motion. In overweight or obese patients or in postoperative patients who cannot report pain accurately or who may have had regional (scalene) anesthesia, this diagnosis can be difficult to make on physical examination. In patients with chronically dislocated shoulders, neurovascular and vascular symptoms can occur because of compression of the humeral head against the brachial plexus. In such patients, the arm is typically held at the side, and although they may have limited motion at the glenohumeral joint, use of the scapulothoracic articulation can provide elevation up to 80 degrees or more. The diagnosis often cannot be made without radiographs, especially scapular Y views or axillary views. Computed tomography may be indicated for some individuals.

Posterior shoulder instability
Posterior shoulder instability can be much more difficult to diagnose on physical examination than anterior instability. One reason is that patients with posterior instability often do not appreciate that the shoulder is subluxing over the posterior glenoid rim; instead, all they feel is pain. However, patients with true posterior shoulder instability often are aware of the position the arm is in when it subluxates or dislocates and are aware that the shoulder is unstable. The patient who has only posterior shoulder pain and who is unsure of what is happening to his or her shoulder is challenging to diagnose.
The other reason posterior shoulder instability is difficult to examine is that the tests described for making the diagnosis of posterior instability have not been studied independently enough to determine their accuracy. The posterior apprehension test described by Kessel 10 in 1982 is the most commonly used test for posterior instability. It is performed by flexing and adducting the arm and pushing posteriorly on the elbow to create an axial load on the posterior aspect of the shoulder ( Fig. 7-5 ). This maneuver is supposed to make the patient apprehensive that the shoulder is going to come out of the socket. Unfortunately, this test is based on a faulty observation based on patients who can show their posterior instability. 11 High-speed cameras show that in patients with posterior shoulder instability, the shoulder does not subluxate in adduction and internal rotation but rather when the arm is slightly abducted and in neutral rotation. The adducted and internally rotated position typically seen in patients who have posterior shoulder instability is actually where the patient rests the arm and not where it subluxates.

FIGURE 7-5 The posterior apprehension test.
As a result, the posterior apprehension test, in which apprehension is the criterion for a positive test, has been found in one unpublished study to have a low sensitivity (42%) and specificity (92%) for posterior instability (as reported by McFarland 1 ). If pain was used as a criterion for a positive posterior apprehension sign, the sensitivity was 52% and the specificity was 86%. 1
Another test described by Matsen et al 12 for posterior instability is the “jerk” test. In this test, the arm of the patient is elevated as an axial load is applied to the shoulder. The arm is brought into adduction and then horizontally extended so that the humeral head subluxes back into the glenoid. Kim et al 13 did not have a control group, but they found that the jerk test was negative in all patients after surgery, so sensitivity (100%) and specificity (100%) for this test were excellent. However, this experience has not been duplicated, and, based on our personal experience, this test is difficult to perform.
The last physical examination test for posterior shoulder instability is laxity testing of the shoulder using a load-and-shift test or a posterior drawer test. 1 These are performed as described previously, except that the examiner directs a posterior force to the proximal humerus to slide the humeral head over the stabilized scapula. The degree of translation can be described using the modified Hawkins classification. 1
To our knowledge, there is only one study that evaluates the results of posterior shoulder laxity testing for making the diagnosis of posterior instability. 1 In that study, a positive test was when the patient reported that the subluxation of the humeral head over the posterior glenoid reproduced the feeling of instability. Using that criterion, the posterior drawer test had a sensitivity of 42%, a specificity of 92%, and a likelihood ratio of 5.30. 1 If pain was used as a criterion for a positive test, then the sensitivity was 50%, the specificity was 82%, and the likelihood ratio was 2.72. 1 In summary, posterior shoulder laxity can be helpful in confirming a diagnosis of posterior instability, but the sensitivity is very low.
Locked posterior dislocations are typically seen after motor vehicle accidents, after seizures, in patients with substance abuse problems, or in patients with massive rotator cuff tears with or without trauma ( Fig. 7-6 ). Such patients can have surprisingly good elevation of their shoulders, markedly restricted external rotation, and varying degrees of pain depending on the length of time from the original instability event. If the patients do not have pain, then the diagnosis of a Charcot joint should be considered from cervical spine conditions (e.g., syrinx), central nervous system problems (e.g., stroke), or substance abuse.

FIGURE 7-6 Patient with a fixed, chronic posterior dislocation of the shoulder.


Pearls

Making the diagnosis of posterior shoulder instability can be helped by obtaining a history of the mechanism of the original injury and also a history of what position the arm is in at the time of symptoms.
Posterior laxity testing can be very helpful in making the diagnosis of posterior shoulder instability.
The posterior apprehension test is frequently not helpful in making the diagnosis of posterior shoulder instability.
The “jerk test” can make the diagnosis of posterior shoulder instability, but it is difficult to perform.

Inferior shoulder instability
True inferior instability of the shoulder in which the patient has symptomatic subluxations or a true inferior dislocation (luxatio erecta) is uncommon. Luxatio erecta has been reported to account for less than 0.5% of all shoulder dislocations. 14 As previously mentioned, this type of dislocation results in substantial damage to the shoulder ligaments, the rotator cuff, and the greater tuberosity of the humerus. Such patients should have a complete neurovascular examination because brachial plexus and vascular injury have been frequently reported with this direction of shoulder instability. 1 , 14
Inferior subluxation of the glenohumeral joint is more difficult to diagnose because true inferior subluxations are uncommon and because of the confusion resulting from the difficulty of making the diagnosis with physical examination findings and the lack of definitive criteria. Specifically, the physical examination tests that are used for measuring inferior laxity of the shoulder have been confused as indicating instability.
This confusion over inferior laxity and inferior instability began when Neer et al 15 described the use of the sulcus sign as a finding in patients with multidirectional instability. In that original study, the authors stated that all their patients had “symptomatic” inferior instability based on a positive sulcus sign. However, they did not say whether the patients had a sense of instability or just pain with sulcus testing, and they did not define what constituted a positive test. As a result, subsequent authors 9 created a grading system in which grade I translation was less than 1.0 cm movement of the humeral head, grade II was 1.0 to 1.5 cm of movement, and grade III was more than 1.5 cm or movement, and many interpreted a high-grade sulcus sign (grade II or III) as indicative of inferior shoulder instability whether or not the patient had symptoms of inferior instability. Consequently, many patients who had unidirectional instability in an anterior or posterior direction were diagnosed with a concomitant inferior instability whether or not they had true symptoms of shoulder instability. Such patients were erroneously given a diagnosis of multidirectional instability based on asymptomatic laxity testing, with the result that studies of nonoperative and operative treatment have a mixed population of patients who had a combination of unidirectional instability and high grades of inferior shoulder laxity.
The sulcus sign can be performed via several methods during the physical examination. We prefer to test both shoulders concurrently with patients sitting because it helps them relax ( Fig. 7-7 ). The arm is tested with the patient relaxed and an inferior force directed on the humerus. The patient is asked if this causes the shoulder to subluxate or slide and if it reproduces symptoms of instability. The patient may report pain with a sulcus sign, but pain cannot be considered to be diagnostic for inferior instability.

FIGURE 7-7 Sulcus testing is best performed with the patient sitting in a relaxed position.
Some authors have suggested that the sulcus sign should be repeated with the arm in external rotation because doing so may indicate laxity of the rotator cuff interval. 1 , 7 However, we have not considered this a critical finding because an increase in laxity with the arm in external rotation is very subjective. A biomechanical study 16 has shown that tightening the rotator cuff interval does not affect inferior translation as much as it tightens external rotation, and clinical studies 17 , 18 have shown that is it not a necessary procedure for treating most patients with shoulder instability.
There are several issues with the use of the sulcus sign in clinical practice. The first issue with inferior laxity testing with the sulcus sign is that the schema used to measure it has never been validated. The range of inferior laxity in normal shoulders was measured using electromagnetic sensors by Harryman et al 19 and found to be 5 mm to 15 mm. Another study 20 suggested that with a sulcus sign, inferior shoulder laxity is 4.7 to 17.6. Although the Harryman et al 19 schema is the most commonly used, it does not reflect true translations of the humeral head.
A second issue with inferior laxity testing with the sulcus sign is that high grades of inferior laxity are not uncommon in asymptomatic individuals who have never had a problem with their shoulders. A study of school-age children (average, 16.6 years old) found that 11% met the criteria for multidirectional instability based on a positive sulcus sign. 21 A study of high-school athletes with no previous shoulder problems found that 9% of females and 3% of males had a grade III sulcus sign. 22
A third issue with inferior laxity testing is that it is not reliable between observers or reproducible when performed twice by one examiner. One study found that in a cohort of patients under anesthesia, the intraobserver reliability was 73% and the interobserver reliability was 70%. 23 As a result, if a sulcus sign is used as a criterion of inferior instability, what one examiner considers excessive laxity may not be the findings of another examiner.
Another physical examination test reported for determining inferior shoulder laxity is the Gagey sign ( Fig. 7-8 ). 24 In this technique, the examiner stabilizes the scapulothoracic articulation and then elevates the arm until the first endpoint is encountered where glenohumeral motion stops and scapulothoracic motion begins. This position of the arm was validated using a cadaver study to indicate the degree of laxity in the inferior capsule of the shoulder. 24 Those authors found that when the angle between the arm and the thorax exceeded 105 degrees, the patient was more likely to have a component of inferior instability in the shoulder. 24 To our knowledge, this test has not been used in any large studies, and its relationship to surgical findings and results warrants additional study.

FIGURE 7-8 The Gagey test for inferior laxity is performed with the patient sitting. This is a normal result under 90 degrees of abduction with the scapular stabilized.
Because of the inexact nature of physical examination testing for inferior shoulder laxity, attempts have been made to measure the inferior laxity with radiographs or ultrasound. These studies have proven inconclusive because the numbers of patients studied are typically small; few asymptomatic patients are studied as controls; the subsequent statistical analysis is lacking; and the relationship of the measurements to shoulder abnormality, treatment, and results have not been shown.


Pearls

True inferior shoulder instability is rare.
A large sulcus sign indicates inferior laxity and not inferior instability.
It is rare for a patient to have symptoms of instability with inferior laxity testing, and pain alone with this test should not confirm the presence of inferior instability.
The use of sulcus testing alone to define multidirectional instability results in an overdiagnosis of that disorder.
Shoulder hyperlaxity alone does not necessarily indicate multidirectional instability.

Multidirectional instability
Because of the confusion over what constitutes symptomatic inferior laxity on physical examination, the definition of multidirectional instability remains protean. The first issue is whether multidirectional instability comprises instability in two or three directions. We think that multidirectional instability studies should divide patients into two groups: those with the more common two-directional form and those with the less common three-directional form. The second issue is whether the instability must be symptomatic in the sense that the patient knows the shoulder is subluxating or dislocating in more than one direction. If pain is used as a criterion for instability, then more patients may be diagnosed with instability in directions that may not be substantiated by radiographs or arthroscopic shoulder surgery. We think that the patient should not be considered unstable in one direction or another unless the patient experiences subluxations in the direction of the presumed instability or unless there are solid criteria to support the direction of instability at the time of arthroscopic evaluation.
There are two major reasons for the overdiagnosis of multidirectional instability. The first reason is laxity testing used as the lone criterion for instability. If a patient has proven traumatic anterior shoulder instability, but has grade II posterior shoulder laxity with a shoulder that can also be subluxated over the posterior glenoid rim, then that patient should not be considered to have multidirectional instability. Similarly, if the same patient has a grade II or III sulcus sign that is asymptomatic or even produces pain, the patient should not be diagnosed as having multidirectional instability unless there are also findings of inferior instability at the time of arthroscopic evaluation (via a superiorly located Hill-Sachs lesion or complete inferior labrum or capsular avulsions). One study found that using laxity testing alone as a criterion for shoulder instability in a cohort of patients with instability yielded the diagnosis of multidirectional instability that could vary from 5% to 80% of the patients. 25
The second reason that multidirectional instability is overdiagnosed is that the laxity of the shoulder joint in athletes has been suggested to represent a form of occult instability and because many of these athletes have severe shoulder laxity in a variety of directions, they have been diagnosed as having multidirectional instability. The first study to suggest that overhead athletes had “occult” shoulder instability as the cause of their shoulder pain was Rowe et al 2 who performed Bankart repairs on overhead athletes with pain and dysfunction of their shoulders. Jobe et al 26 subsequently popularized this idea that overhead athletes had a form of anterior shoulder instability because of stretching of the inferior glenohumeral ligaments. Since that time, it has become dogma that any overhead athlete with a painful shoulder has abnormal shoulder laxity and instability as a cause of the pain. The reality is that no one to date has deciphered completely the exact cause of pain in this subgroup of patients.
However, the high degree of shoulder laxity (which presumably is normal) in these patients has been noticed by some authors. 1 Gerber 27 suggested that such patients have a normal “physiologic hyperlaxity,” and that patients who have legitimate instability should be called “anterior instability with physiologic hyperlaxity.” Walch et al 28 called such conditions “the painful athletic shoulder” to refer to patients involved in overhead sports who surgically are typically shown to have partial rotator cuff tears and superior labrum lesions. We jokingly have called such patients “loosy-goosy shoulders with pain,” but think that because this laxity is normal for this sports participation, the individuals should be said to have “physiologic laxity with pain.” Until the exact cause of pain is determined in such patients, it remains confusing and inexact to say they have multidirectional instability.


Pearls

True multidirectional instability is where the patient has symptoms of instability in more than one direction and is uncommon.
True instability in one direction with hyperlaxity in other directions is the more common clinical presentation of patients who are loose jointed.
It is controversial when inferior laxity needs to be treated surgically, and nonoperative treatment is the first treatment of choice.

References

1. McFarland EG. Instability and laxity. Kim TK, Park HB, El Rassi G, Gill H, Keyurapan E, editors, Examination of the shoulder: The complete guide. New York: Thieme; 2006:162-212.
2. Rowe CR, et al. Recurrent transient subluxation of the shoulder. J Bone Joint Surg Am . 1981;63(6):863-872.
3. Lo IKY, et al. An evaluation of the apprehension, relocation, and surprise tests for anterior shoulder instability. Am J Sports Med . 2004;32(2):301-307.
4. Farber AJ, et al. Clinical assessment of three common tests for traumatic anterior shoulder instability. J Bone Joint Surg Am . 2006;88(7):1467-1474.
5. Jobe FW, et al. Shoulder pain in the overhand or throwing athlete. The relationship of anterior instability and rotator cuff impingement [published erratum appears in Orthop Rev 18(12):1268, 1989]. Orthop Rev . 1989;18:963-975.
6. Gerber C, et al. Clinical assessment of instability of the shoulder. With special reference to anterior and posterior drawer tests. J Bone Joint Surg Br . 1984;66(4):551-556.
7. Silliman JF, et al. Classification and physical diagnosis of instability of the shoulder. Clin Orthop Relat Res . 1993;291:7-19.
8. Jia X, et al. An analysis of shoulder laxity in patients undergoing shoulder surgery. J Bone Joint Surg Am . 2009;91(9):2144-2150.
9. McFarland EG, et al. Posterior shoulder laxity in asymptomatic athletes. Am J Sports Med . 1996;24(4):468-471.
10. Kessel L. Clinical disorders of the shoulder . New York: Churchill Livingstone; 1982.
11. McFarland EG. Electromyographic analysis of recurrent posterior instability of the shoulder. In: Post M, Morrey BF, Hawkins RJ, et al, editors. Surgery of the shoulder . St. Louis: Mosby-Year Book; 1990:112-116.
12. Matsen FAIII. Glenohumeral instability. In: Rockwood CAJr, Matsen FAIII, et al, editors. The shoulder . ed 2. Philadelphia: WB Saunders; 1998:611-754.
13. Kim SH, et al. Arthroscopic posterior labral repair and capsular shift for traumatic unidirectional recurrent posterior subluxation of the shoulder. J Bone Joint Surg Am . 2003;85(8):1479-1487.
14. Yanturali S, et al. Luxatio erecta: Clinical presentation and management in the emergency department. J Emerg Med . 2005;29(1):85-89.
15. Neer CSII, et al. Inferior capsular shift for involuntary inferior and multidirectional instability of the shoulder. A preliminary report. J Bone Joint Surg Am . 1980;62(6):897-908.
16. Werner CML, et al. The effect of capsular tightening on humeral head translations. J Orthop Res . 2004;22(1):194-201.
17. Provencher MT, et al. Arthroscopic treatment of posterior shoulder instability: Results in 33 patients. Am J Sports Med . 2005;33(10):1463-1471.
18. Williams RJIII, et al. Arthroscopic repair for traumatic posterior shoulder instability. Am J Sports Med . 2003;31(2):203-209.
19. Harryman DTII, et al. Laxity of the normal glenohumeral joint: A quantitative in vivo assessment. J Shoulder Elbow Surg . 1992;1(2):66-76.
20. Sauers EL, et al. Validity of an instrumented measurement technique for quantifying glenohumeral joint laxity and stiffness [abstr]. J Athl Train . 2001;36(2 Suppl):S-40.
21. Emery RJH, et al. Glenohumeral joint instability in normal adolescents. Incidence and significance. J Bone Joint Surg Br . 1991;73(3):406-408.
22. Lintner SA, et al. Glenohumeral translation in the asymptomatic athlete’s shoulder and its relationship to other clinically measurable anthropometric variables. Am J Sports Med . 1996;24(6):716-720.
23. McFarland EG, et al. Evaluation of shoulder laxity. Sports Med . 1996;22(4):264-272.
24. Gagey OJ, et al. The hyperabduction test. J Bone Joint Surg Br . 2001;83(1):69-74.
25. McFarland EG, et al. The effect of variation in definition on the diagnosis of multidirectional instability of the shoulder. J Bone Joint Surg Am . 2003;85(11):2138-2144.
26. Jobe CM, et al. Evaluation of impingement syndromes in the overhead-throwing athlete. J Athl Train . 2000;35(3):293-299.
27. Gerber C. Observations on the classification of instability. In: Warner JJP, Iannotti JP, Gerber C, editors. Complex and revision problems in shoulder surgery . Philadelphia: Lippincott-Raven Publishers; 1997:9-18.
28. Walch G, et al. Impingement of the deep surface of the supraspinatus tendon on the posterosuperior glenoid rim: An arthroscopic study. J Shoulder Elbow Surg . 1992;1(5):238-245.

Suggested readings

Farber AJ, et al. Clinical assessment of three common tests for traumatic anterior shoulder instability. J Bone Joint Surg Am . 2006;88(7):1467-1474.
Level of evidence: Diagnostic study, Level 1
Summary: This study evaluates the clinical usefulness of three tests for traumatic anterior instability: anterior relocation, apprehension, and anterior drawer tests. The authors found these tests to be diagnostic if the symptoms of instability were reproduced but not when they produce pain
Harryman DT, II, et al. Laxity of the normal glenohumeral joint: A quantitative in vivo assessment. J Shoulder Elbow Surg . 1992;1(2):66-76.
Level of evidence: Diagnostic study, Level 1
Summary: This article is a quantitative study of the clinical in vivo laxity in normal shoulders. The authors used a spatial tracker to assess the motion of the humerus and scapula while manual laxity testing was performed and showed a wide range of normal shoulder laxities in the anterior, posterior, and inferior directions
Jobe FW, et al. Shoulder pain in the overhand or throwing athlete. The relationship of anterior instability and rotator cuff impingement published erratum appears in Orthop Rev 18(12):1268, 1989. Orthop Rev . 1989;18:963-975.
Level of evidence: Diagnostic study, Level 5
Summary: In this article, the authors advocated the concept that shoulder pain in the throwing athlete can be a result of loss of the stabilizing mechanisms of the glenohumeral joint. They suggested that the use of the apprehension test followed by the relocation test is the most sensitive way to detect occult glenohumeral subluxation
Lo IKY, et al. An evaluation of the apprehension, relocation, and surprise tests for anterior shoulder instability. Am J Sports Med . 2004;32(2):301-307.
Level of evidence: Diagnostic study, Level 1
Summary: This study is one of the few that statistically evaluate the usefulness of the apprehension, relocation, and surprise tests for anterior shoulder instability. Although the surprise test is helpful for making the diagnosis of anterior instability, the authors urge caution about the use of the test in clinical practice
Walch G, et al. Impingement of the deep surface of the supraspinatus tendon on the posterosuperior glenoid rim: An arthroscopic study. J Shoulder Elbow Surg . 1992;1(5):238-245.
Level of evidence: Diagnostic study, Level 3
Summary: In this study, 17 athletes who presented with unexplained shoulder pain and subsequently underwent arthroscopic evaluation were found at the time of arthroscopy to have contact of the rotator cuff to the posterior superior glenoid when the arm was placed in abduction and external rotation. The authors indicated that this contact might be a source of pain and disability in this population
CHAPTER 8 Radiographic studies and findings

Giuseppe Porcellini, MD, Francesco Fauci, MD, Fabrizio Campi, MD, Paolo Paladini, MD

Key points

The treatment of instability requires precise identification of the underlying lesion through clinical examination and diagnostic imaging.
Visualization and treatment of any associated lesions are essential because the lesions are often associated with pain and poor outcomes.
The diagnosis of shoulder instability involves a workup that begins with plain x-rays and is completed with magnetic resonance imaging or magnetic resonance arthrography.
Dedicated views and approaches have been developed to address multiple types of shoulder lesions.

Introduction
Improvements in anatomic and biomechanical knowledge and in arthroscopic techniques now allow ad hoc management of all lesions underlying shoulder instability and restoration of the premorbid anatomy to prevent recurrences. Hence precise lesion identification through clinical examination and diagnostic imaging is needed not only to address the primary lesion but also to depict any associated lesions, which are often related to pain and poor outcomes.
Lesions change as a function of time since the first dislocation, the number of dislocations, and patient age. The diagnosis of shoulder instability involves a workup that begins with plain x-rays and is completed with magnetic resonance (MR) arthrography.

Imaging evaluation

Plain x-rays
The anterior or posterior direction of the instability is established on plain films. X-rays demonstrate bone lesions such as glenoid fracture, Hill-Sachs lesion, and fracture of the tuberosities or of the proximal humeral epiphysis. Patients presenting with an acute lesion undergo the trauma series, whereas the true anteroposterior (AP), axillary, West Point, and Stryker notch views are essential in those with chronic instability because they demonstrate any glenoid or humeral lesions (e.g., Bankart and Hill-Sachs lesions).

Standard anteroposterior view
The standard AP view is an oblique view in which the humeral head and the glenoid partially overlap because of the anterior tilt (approximately 40 degrees) of the beam directed toward the humeral head. This view can be obtained in internal and external rotation to demonstrate a Hill-Sachs lesion ( Fig. 8-1 ).

FIGURE 8-1 Plain x-rays, standard anteroposterior view. A, External rotation. B, Internal rotation: the dashed line outlines a Hill-Sachs fracture. C, AP x-ray in the plane of the body. An AP view in the coronal plane of the body is of limited use in the evaluation of the glenohumeral joint, the joint space, or the relationship of the humeral head to the glenoid fossa.
(Modified from Matsen FA, III, et al: Shoulder surgery: Principles and procedures, Philadelphia, 2004, WB Saunders, p 7.)

True anteroposterior (grashey) view
The beam directed lateral to the scapula (45 degrees) affords optimal visualization of the glenohumeral (GH) joint, with the overlying anterior and posterior glenoid rim highlighting the joint line. This view clearly demonstrates any erosion of the anterior glenoid rim that fails to be depicted ( Fig. 8-2 ).

FIGURE 8-2 A, AP x-ray in the plane of the scapula. An AP view in the plane of the scapula reveals the glenohumeral joint space and demonstrates whether the humeral head has a normal relationship to the glenoid fossa. It is most easily taken by positioning the patient’s scapula flat on the cassette and then passing the x-ray beam at right angles to the film, aiming at the coracoid process. B, A simulated x-ray view of a scapular AP view using a backlighted skeletal model. This view reveals the radiographic glenohumeral joint space and provides a good opportunity to detect fractures of the humerus or glenoid lip. C, Plain x-rays: True anteroposterior (Grashey) view. Intact glenoid rim. D, Erosion of anterior glenoid rim (dashed line).
( A modified from Matsen FA, III, et al: Shoulder surgery: Principles and procedures, Philadelphia, 2004, WB Saunders, p 7. B from Rockwood CA, et al: The shoulder, ed 4, Philadelphia, 2009, Saunders Elsevier.)

West point view ( fig. 8-3 )
For this variant of the AP view, the patient lies prone, arm in 90 degrees of abduction and elbow hanging over the edge of the examination table. The beam has an approximate 25 degrees anterior and medial tilt to demonstrate the anteroinferior glenoid rim. This view is difficult to obtain in noncooperative patients and in acute dislocation because of pain. The West Point view is also helpful in the workup of suspected glenoid bone loss because it provides an excellent view of the anterior glenoid rim.

FIGURE 8-3 West Point axillary view helps provide excellent visualization of the anterior glenoid rim.
(Redrawn from Rokous JR, et al: Modified axillary roentgenogram. Clin Orthop Relat Res 82: 84–86, 1972.)

Stryker notch view ( fig. 8-4 )
This variant of the AP view is obtained with the patient lying supine, the arm abducted and externally rotated and the palm behind the head. The beam has approximately 10 degrees of cephalic inclination to display the posterolateral humeral head and document Hill-Sachs fractures. The Stryker notch view is important to help with evaluation of humeral head Hill-Sachs lesions. In addition, an internal rotation view also may be helpful to visualize Hill-Sachs injuries ( Fig. 8-4 , D ).

FIGURE 8-4 A, Apical oblique view. The shoulder is positioned as for an anteroposterior view in the plane of the scapula except that the x-ray beam is angled inferiorly at an angle of 45 degrees. This reveals the contour of the posterolateral humeral head and the anteroinferior glenoid. Solid arrow indicates Hill-Sachs defect. Dashed arrow indicates anteroinferior glenoid defect. B, Stryker notch view. C, Position of the patient for the Stryker notch view. The Stryker notch view is helpful for identification of humeral head bony injuries. The patient is supine with the cassette posterior to the shoulder. The humerus is flexed approximately 120 degrees so that the hand can be placed on top of the patient’s head. Note that the angle of the x-ray tube is 10 degrees superior. D, Defects in the posterolateral aspect of the humeral head are seen in three different patients with recurring anterior dislocations of the shoulder.
( A redrawn from Matsen FA, III, et al: Shoulder surgery: Principles and procedures, Philadelphia, 2004, WB Saunders, p 12. B redrawn from Hall RH, et al: Dislocations of the shoulder with special reference to accompanying small fractures. J Bone Joint Surg Am 41:489–494, 1959. C and D modified from the work of Hall RH, et al: Dislocation of the shoulder with special reference to accompanying small fractures. J Bone Joint Surg Am 41:489–494, 1959; appearing in Rockwood CA, et al: The shoulder, ed 4, Philadelphia, 2009, Saunders Elsevier, p 187.)

Axillary view ( fig. 8-5 )
The beam is directed toward the axillary cavity, with a medial tilt of approximately 15 degrees, and the arm is abducted. It depicts any anterior glenoid rim bone fragments, which may be related to a bony Bankart lesion, and erosion of the anteroinferior portion of the glenoid rim (see Fig. 8-5 , C ).

FIGURE 8-5 A, The dashed line outlines the normal shape of the anterior glenoid rim. B, The dashed line outlines the anterior glenoid bone loss. C, Patient and beam positioning for axillary view and modifications of the axillary view. An axillary x-ray reveals the glenohumeral joint space and the AP position of the humeral head and glenoid fossa. It is obtained by having the patient’s arm in abduction (e.g., holding onto an IV pole), the cassette on the superior aspect of the shoulder, and the x-ray beam passing up the axilla, aiming at the coracoids. D, The axillary view with a curved cassette, a method that is useful if the arm cannot be adequately abducted for a routine axillary view. E, The Velpeau axillary lateral x-ray technique. With the arm in a sling, the patient leans backward until the shoulder is over the cassette. F, A trauma axillary lateral radiograph. The arm is flexed on a foam wedge.
( C redrawn from Matsen FA, III, et al: Shoulder surgery: Principles and procedures, Philadelphia, 2004, WB Saunders, p 9. D redrawn from Rockwood CA, et al: The shoulder, ed 4, Philadelphia, 2009, Saunders Elsevier, p 667. E redrawn from Bloom MH, et al: Diagnosis of posterior dislocation of the shoulder with use of the Velpeau axillary and angle-up roentgenographic views. J Bone Joint Surg Am 49:943–949, 1967. F redrawn from Rockwood CA, et al: The shoulder, ed 4, Philadelphia, 2009, Saunders Elsevier, p 668.)

Transcapular (Y) view
In the Y view, the beam is trained directly onto the scapular plane, with a tilt of approximately 60 degrees compared to the AP view. This view provides information on the subacromial space and is performed in patients with posterior chronic dislocation because it demonstrates the static posterior dislocation of the humeral head with respect to the glenoid.

Dynamic x-ray examination
As suggested by its name, dynamic x-ray examination allows functional fluoroscopic study of the shoulder. The drawer test is performed with the patient awake or under general anesthesia. The contralateral shoulder also needs to be examined in patients with constitutional laxity or multidirectional instability. Anterior head movement up to 25% of its surface and posterior movement by 30% to 50% are held to be in the normal range. This examination is not easy to perform in acute conditions because of patient apprehension and pain.

Considerations
Plain films are the mainstay of the diagnostic workup for GH joint instability. Radiologist and surgeon experience and patient clinical condition and collaboration guide in the choice of views and techniques. X-rays specifically depict bone lesions, which are a common consequence of acute and chronic dislocation. Bone loss significantly affects the prognosis and management of instability, even though the extent to which it does so is debated. Hill-Sachs fractures are usually demonstrated on AP views with the arm in internal rotation, the larger ones with the arm in neutral or external rotation. Visualization of a Hill-Sachs fracture in external rotation has an adverse prognostic significance.
The true AP view affords diagnosis of superior subluxation and of other lesions of the acromioclavicular joint, collarbone, and ribs, as well as of glenoid hypoplasia, a rare congenital condition involving absence or marked reduction of the glenoid neck. Glenoid hypoplasia is often associated with recurrent dislocation; hence, there is x-ray evidence of GH arthritis, bone spurs, and intra-articular loose bodies. When excessive glenoid retroversion with respect to the humerus is the suspected cause of instability, a CT scan is the most informative examination. Finally, a ganglion cyst at the level of the lower glenoid region may be associated with pain and GH joint dislocation. In such cases, the frequent clinical finding of supraspinatus and infraspinatus hypotrophy is well documented on MRI. In overhead and thrower athletes, such as baseball pitchers, plain films can demonstrate specific lesions such as Bennett lesion, which involves a bony spur on the posterior-inferior surface of the glenoid. When Bennett first described it, in 1941, he attributed spur formation to traction of the brachial triceps on the infraglenoid tubercle and suggested a dedicated view with the beam tilted 5 degrees cephalad and the arm in 90 degrees of abduction and 90 degrees of external rotation. In fact, this lesion is due to ossification of the posterior band of the inferior glenohumeral ligament (IGHL), and the bone spur is due to the impact of the humeral head on the posterior glenoid with each throwing movement.

Arthrography
Arthrography, which became routine in the 1970s and 1980s, has now been superseded by computed tomography (CT) arthrography and MR arthrography. It is still used to disclose rotator cuff lesions through leakage of the contrast agent into the subacromial space in the early phases of contrast-enhanced CT or MRI.

Computed tomography scan
The introduction of CT was a major advance in diagnostic imaging of the unstable shoulder. Despite key limitations compared with MRI (i.e., lack of multiplanar imaging, exposure to ionizing radiation, and poor specificity for labral lesions without dislocation) CT with intra-articular injection of an iodinated contrast agent is a useful technique. CT is superior to MRI in documenting two major findings: glenoid bone lesions and Hill-Sachs fracture. 1 - 4
Hill-Sachs fracture has a large role in shoulder instability because its site and depth affect the rate of recurrence. There is no accepted or validated method to measure glenoid bone erosion. Large osseous defects are associated with poorer outcomes if managed by arthroscopic repair without bone grafting. 5 - 9
Glenoid bone lesions account for 10% to 70% of cases of instability. Bigliani first proposed the term “glenoid lesions” in 1998. CT has high sensitivity (93%) and specificity (78%) for the glenoid bone and for diagnosing shoulder instability based on rim changes and erosion ( Fig. 8-6 ). Examination of the contralateral shoulder is essential. The first three-dimensional glenoid studies were reported by Nobuhara ( Fig. 8-7 ). The bone defect is classified as large when it involves >20% of the glenoid surface, medium when it involves 5% to 20% of the glenoid, or small when it involves <5% of the glenoid. CT scans correlate well with arthroscopic examination. It is difficult to define the extent of bone erosion excluding arthroscopic repair. Two cutoffs have been suggested: a 25% reduction in glenoid width, or a glenoid width-to-length ratio <79%. The width of the glenoid is usually slightly greater than two thirds of its length, with a mean width-to-length ratio of approximately 0.7. A width reduction without changes in length involves a reduction of the width-to-length ratio. Glenoid retroversion and anterior scapular tilt can affect the calculation.

FIGURE 8-6 A, Parasagittal CT scan, entire glenoid rim. B, Parasagittal CT scan: arrows indicate bone erosion of the anterior glenoid rim.

FIGURE 8-7 CT and MRI: A, Three-dimensional CT: Arrow indicates the bone fragment detached from the anterior glenoid rim. B, Parasagittal CT scan: arrow indicates the bone fragment detached from the anterior glenoid rim. C, Axial CT scan: arrow indicates the bone fragment detached from the anterior glenoid rim. D, Axial MRI scan: arrow indicates the bone fragment detached from the anterior glenoid rim.


Pearls

Glenoid bone loss is important to recognize. Dedicated plain radiographic views such as the West Point and axillary views are important to detect the presence of glenoid bone loss.
The precise determination of glenoid bone loss is best obtained with computed tomography, and three-dimensional reconstruction images. An en face view of the glenoid with the humeral head digitally subtracted provides excellent visualization of the glenoid and can accurately determine the extent of glenoid bone loss.
A posterior bony lesion (Bennet lesion) may be visualized in a throwing shoulder or with recurrent posterior shoulder instability.
Hill-Sachs injuries are best visualized on plain radiographs with the Stryker or internal rotation views. Advanced imaging will help quantify the extent of Hill-Sachs injury.

Magnetic resonance imaging and magnetic resonance arthrography
In addition to the common glenoid rim lesions, patients with GH joint instability can have more complex soft tissue lesions of capsule, rotator cuff, glenohumeral ligaments (GHL), and cartilage. The glenoid rim, GHL, capsule, and subscapularis tendon are isointense to the surrounding anatomic structures. Conventional MRI is accurate, sensitive, and specific for GH instability and cuff lesions. A sensitivity of 78% to 93% and a specificity of 68% to 80% in diagnosing glenoid rim lesions have been reported in different studies. Injection of an intra-articular contrast agent increases sensitivity and specificity to 91% and 93%, respectively. 10 - 12

Normal capsule and ligament anatomy and pitfalls in MRI interpretation
The MRI study of asymptomatic shoulders is critical to understanding the normal anatomic variants of the capsular-labral complex. Labrum thickness is variable. Its anterior and posterior portions are well demonstrated on axial scans and its superior portion on coronal images. The normal labrum has a triangular morphology both anteriorly (64%) and posteriorly (47%). A rounded variant is seen anteriorly in 17% of cases and posteriorly in 33%, and a flat labrum in 2% and 17% of cases, respectively. In addition, the normal anterior labrum appears cleaved or notched in 11% and 3% of shoulders, respectively. Absence of the labrum is rarer. The posterior labrum is more likely to be rounded or flat. Three anatomic variants of capsular insertion are recognized ( Fig. 8-8 ): (1) at the level of the labrum (type 1), (2) at the level of the labrum-glenoid junction (type 2), and (3) medial to the labrum (type 3, the least common).

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