Biomechanical analysis of rollator walking

Alkjær Tine, Larsen, Pedersen Gitte, Nielsen, Simonsen

Description

The rollator is a very popular walking aid. However, knowledge about how a rollator affects the walking patterns is limited. Thus, the purpose of the study was to investigate the biomechanical effects of walking with and without a rollator on the walking pattern in healthy subjects. Methods The walking pattern during walking with and without rollator was analyzed using a three-dimensional inverse dynamics method. Sagittal joint dynamics and kinematics of the ankle, knee and hip were calculated. In addition, hip joint dynamics and kinematics in the frontal plane were calculated. Seven healthy women participated in the study. Results The hip was more flexed while the knee and ankle joints were less flexed/dorsiflexed during rollator walking. The ROM of the ankle and knee joints was reduced during rollator-walking. Rollator-walking caused a reduction in the knee extensor moment by 50% when compared to normal walking. The ankle plantarflexor and hip abductor moments were smaller when walking with a rollator. In contrast, the angular impulse of the hip extensors was significantly increased during rollator-walking. Conclusion Walking with a rollator unloaded the ankle and especially the knee extensors, increased the hip flexion and thus the contribution of hip extensors to produce movement. Thus, rollator walking did not result in an overall unloading of the muscles and joints of the lower extremities. However, the long-term effect of rollator walking is unknown and further investigation in this field is needed.

Informations

• Publié par: biomed
• Publié le: 01 janvier 2006
• Nombre de lectures: 10
• Langue: English

Extrait

BioMed CentralBioMedical Engineering OnLine
Open AccessResearch
Biomechanical analysis of rollator walking
Tine Alkjær*, Peter K Larsen, Gitte Pedersen, Linda H Nielsen and
Erik B Simonsen
Address: Institute of Medical Anatomy, The Panum Institute, University of Copenhagen, Blegdamsvej 3C, DK-2200 Copenhagen N, Denmark
Email: Tine Alkjær* - [e-mail]; Peter K Larsen - [e-mail]; Gitte Pedersen - [e-mail];
Linda H Nielsen - [e-mail]; Erik B Simonsen - [e-mail]
* Corresponding author
Published: 06 January 2006 Received: 31 October 2005
Accepted: 06 January 2006
BioMedical Engineering OnLine 2006, 5:2 doi:10.1186/1475-925X-5-2
This article is available from: http://www.biomedical-engineering-online.com/content/5/1/2
© 2006 Alkjær et al; licensee BioMed Central Ltd.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0),
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
Background: The rollator is a very popular walking aid. However, knowledge about how a
rollator affects the walking patterns is limited. Thus, the purpose of the study was to investigate
the biomechanical effects of walking with and without a rollator on the walking pattern in healthy
subjects.
Methods: The walking pattern during walking with and without rollator was analyzed using a
three-dimensional inverse dynamics method. Sagittal joint dynamics and kinematics of the ankle,
knee and hip were calculated. In addition, hip joint dynamics and kinematics in the frontal plane
were calculated. Seven healthy women participated in the study.
Results: The hip was more flexed while the knee and ankle joints were less flexed/dorsiflexed
during rollator walking. The ROM of the ankle and knee joints was reduced during rollator-walking.
Rollator-walking caused a reduction in the knee extensor moment by 50% when compared to
normal walking. The ankle plantarflexor and hip abductor moments were smaller when walking
with a rollator. In contrast, the angular impulse of the hip extensors was significantly increased
during rollator-walking.
Conclusion: Walking with a rollator unloaded the ankle and especially the knee extensors,
increased the hip flexion and thus the contribution of hip extensors to produce movement. Thus,
rollator walking did not result in an overall unloading of the muscles and joints of the lower
extremities. However, the long-term effect of rollator walking is unknown and further investigation
in this field is needed.
wheeled walker", four-wheeled walker" [2-4] are fre-Background
The rollator is a popular assistive walking device in most quently used synonymously with rollator, which can be
European and especially the Nordic countries [1]. The defined as a frame with three or four wheels; the rollator
exact number of rollator users is unknown but about has handles with brakes, and in some cases it has a seat, a
6.4% of Danish 56–84 year-old people use a rollator and basket or a tray (Fig. 1) [1].
in Sweden about 4% of the total population use a rollator
[1]. The terms "wheeled walker", "rolling walker",
"threePage 1 of 7
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tern parameters when walking with a rollator have not yet
been quantified.
It is unclear whether an unloading of certain muscle
groups and joints during walking would impair the
functional ability during other types of daily physical activities
and movements like sit-to-stand, short walking distances,
stair climbing, balance control during standing/squatting
etc. One study concluded that the use of walking-aids
combined with a high activity level may protect against
falls in elderly subjects [9]. Thus, information about how
muscle groups and joints in the lower extremities are
affected by walking with a rollator may be used in the
development of specific rehabilitation strategies in elderly
and disabled rollator users.
Accordingly, the purpose of the present study was to
investigate the biomechanical effects of walking with a
rollator on the walking pattern of healthy subjects. The
reason for studying a group of healthy subjects was that it
was both unethical and difficult to ask actual rollator
users to walk without their rollator.
Methods
SubjectsThFigure 1Swis rollator, eden, was used in the studya Dolmite Maxi 650, Dolomite AB, Anderstorp,
ThBSeven healthy women (age: 34.7 (range: 25–57) years,
Sweden, was used in the study. It resembles a typical rollator height: 1.70 (range: 1.64–1.78) m, weight: 64.7 (range:
with four wheels, handles with brakes and a seat. 55–75) kg) participated in the study. None of the subjects
had any history of injuries or musculo-skeletal
dysfunctions in their lower extremities. All subjects gave their
The main purpose of using a rollator is to improve the informed consent to participate in the experiments which
walking performance and minimize the risk of falling. were approved by the local ethics committee.
Studies have shown that the walking performance in
elderly subjects measured in terms of distance, cadence and Gait analysis
velocity is improved when they walk with a rollator [2]. The subjects were fitted with fifteen small reflecting
spherFurthermore, a recent study has shown that rollator users ical markers (12-mm diameter) according to the marker
are generally satisfied with their rollator and consider it an set-up described by Vaughan et al. [10]. The markers were
important prerequisite for living a socially active and placed on the head of the fifth metatarsal, the heel, the
latindependent life [1]. eral malleous, the tibial tubercle, the lateral femoral
epicondyle, the greater trochanter, the anterior superior iliac
However, knowledge about how the rollator affects the spine and sacrum. All subjects wore lightweight flexible
walking pattern is limited. To our knowledge no studies shoes with a thin, flat sole. The subjects were asked to
have investigated the biomechanical differences between walk across two force platforms (AMTI, OR6-5-1) both
walking with and without a rollator except from one study with and without a rollator (Fig. 1, Dolmite Maxi 650,
that observed a reduction in the vertical ground reaction Dolomite AB, Anderstorp, Sweden) at a speed of 4.5 km/
force during rollator walking [5]. Such information may h. The rollator was adjusted to each subject in an upright
be clinically relevant in the decision-making process of standing position with the arms hanging down along the
whether a rollator would be beneficial to a subject or not, body so that the handles were on a level with processus
or whether the use of a rollator should be supplemented styloideus ulnae. The Dolmite Maxi 650 rollator model
with e.g. balance and/or strength training. Studies of walk- was used because it was wide enough to pass next to the
ing with canes or walking poles have shown that these force platforms without touching them. However, pilot
walking-aids reduce the load on the lower extremities [6- studies showed that the wheels of the rollator sometimes
8]. Presumably, the rollator reduces the loads on the leg hit the first platform anyway. To solve this problem a
muscles and the joints to some extent as well. However, metal rail was fixed to the ground along the first platform
the specific changes in kinematic and kinetic walking pat- to ensure that the rollator wheels did not touch it.
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The subjects were allowed to practice walking both with the angular impulse (Nm· s) was calculated by
integraand without the rollator to become familiar with the tion of the area under the joint moment curves. The
angumovements and the pre-determined walking speed. The lar impulses of the plantarflexors (i.e. the negative part of
speed was controlled by photocells, which made it possi- the ankle moment), knee extensors (i.e. the first positive
ble to teach the subjects to approach 4.5 km/h. part of the knee moment) and the hip extensors (i.e. the
negative part of the sagittal hip moment curve), flexors
Five video cameras (Panasonic WV-GL350) operating at (i.e. the positive part of the sagittal hip moment curve)
50 Hz were used to record the movements. The video sig- and abductors (i.e. the positive part of the frontal hip
nals and the force plate signals were synchronized elec- moment curve).
tronically with a custom-built device. The device put a
visual marker on one video field from all cameras and at The peak values as well as the angular impulses of the
the same time triggered the analogue-to-digital converter ankle, knee and hip moment were calculated and used as
which sampled the force plate signals at 1000 Hz. The input parameters for the statistical analyses.
subjects triggered the data sampling and synchronization
when they passed the first photocell. The angular position of the ankle, knee and hip joints was
calculated to describe the movements in the sagittal plane.
The video sequences were digitized and stored on a PC