Improving partial weight bearing compliance of patients after lower limb surgery using an auditory feedback device: a feasibility study

After some types of surgery on the lower extremity of a patient, partial weight
bearing is instructed by the surgeon or physician. During the course of
rehabilitation, usually several weeks, the allowed load is slowly increased
until full weight can be applied. The partial weight bearing on the affected
limb, is achieved by the use of crutches or a walking frame. The assessment of
the applied load on the limb in case of partial weight bearing is often
difficult. The instruction of the allowed load consists of indicating the
allowed static load on the limb using scales. Patients are often unable to
translate this static force when walking. In the present study, the feasibility
of a wearable system for providing biofeedback of the maximum allowed load is
investigated. The Auditory BioFeedback (ABF) device used in this study, uses a
load measuring insole combined with a battery powered data analy-sis ankle
brace. The allowed load can be programmed into the ankle brace by the
physician. When this load is exceeded, an alarm is sounded warning the patient
of overloading. Using the ABF device, patients will have an indication of
allowed load during walking opposed to the now used static load. Furthermore,
the patients will be warned every time the allowed load is exceeded. The
hypothesis is, that using this system, the patients quickly learn to apply the
right load during walking. During the learning curve, the interval of the
sounded alarms will decrease. This less often overloading of the limb, could be
beneficial to the rehabilitation process.

Primary Objective:
To determine whether it is feasible to use an ABF device to lower the amount of
steps that exceed the maximum allowed force.
The specific research question that the study aims to answer is:
- Is it possible to increase partial weight bearing compliance using an
Auditory BioFeedback device?

The present study is conducted in preparation of a future randomized controlled
trial, investigating the ability of an Auditory BioFeedback (ABF) device for
partial weight bearing to reduce rehabilitation time of patients that have
undergone leg surgery.

Secondary Objective:
To determine whether the use of a ABF device is satisfactory for patients.
Specific research questions that the study aims to answer are:
- Is the use of biofeedback technology easy to use for therapists and patients?
- Does the biofeedback signal provide the patient with usable information?
- Is there user acceptance and satisfaction of complying with partial weight
bearing instruc-tions of the device?

Prior to the patients normal physical therapy session, a normal part of their
rehabilitation process after surgery, subjects will participate in the study.
First their weight will be determined using a scale. With this measurement, and
the percentage allowed maximum load assigned to the patients by their
physician, the maximum allowed force will be determined. The amount of loading
of the limb to achieve this force, is demonstrated to the patient using a
scale. The Auditory BioFeedback (ABF) device will be setup to this maximum
force.
At the start of the measurements, subjects will be equipped with the ABF device
and explained how to walk with crutches to achieve partial limb loading.
Subjects will first walk for five minutes on the treadmill with the ABF device
turned off. During this time, patients will try to apply no more than the
maximum allowed load to the affected limb. The ground reaction force of walking
will be recorded by the ABF device. Patients will not receive feedback on the
forces that are recorded. After five minutes of walking the subjects will take
a short brake while the ABF device is turned on and an explanation of the
functioning of the device is given. After this, patients will again walk with
crutches for five minutes while forces are again recorded. During this time,
they are encouraged to reduce the load on their limb when the ABF device gives
a warning. After the five minutes walking a second short brake takes place.
After this second short brake while the ABF device is turned off, subjects will
again walk for five minutes. During this time no feedback is given from the ABF
device, the forces will be recorded.
After the walking tests, a short interview will be conducted with the subjects.
In this interview, subjects will be asked about their experience with the ABF
device and asked if they feel the use of the device made a difference in their
partial weight bearing.

All measurements are non-invasive and place the patient at no risk other than
normal walking on a treadmill. During all evaluations, the researcher will
guard the subject to minimize the risk of falls. During training, the potential
risks are minimal since the subjects perform the training under supervision.

Potential benefits of the proposed research to the subjects and others:
Subjects that participate in this study are better guided in the process of
partial limb loading af-ter they have undergone surgery. This might lead to
less overloading of the limb, achieving a bet-ter rehabilitation process. If
less overloading of the affected limb is a benefit in the rehabilitation
process is not known. Past studies suggest that patient are not able to comply
with the weight bearing instructions. This study intended to find if a Auditory
BioFeedback (AFB) device is able to assist patients in complying to the
instructions. In case the ABF device is able to achieve this, a subsequent
large scale Randomized Controlled Trial will have to prove the benefit of
partial limb loading on the rehabilitation process. The results of this study
could benefit all future patients that undergo surgery on the lower
extremities.