Clinical Trial Details
— Status: Completed
Administrative data
NCT number |
NCT02902211 |
Other study ID # |
0485-16-FB |
Secondary ID |
|
Status |
Completed |
Phase |
N/A
|
First received |
|
Last updated |
|
Start date |
July 7, 2017 |
Est. completion date |
June 30, 2023 |
Study information
Verified date |
January 2024 |
Source |
University of Nebraska |
Contact |
n/a |
Is FDA regulated |
No |
Health authority |
|
Study type |
Interventional
|
Clinical Trial Summary
This study will determine whether an ankle foot orthosis (AFO) improves walking performance
in patients with PAD from its first use. Additionally, the study will test walking
performance after a three month AFO intervention and will examine the feasibility of this AFO
intervention.
Data for evaluations will be collected from 50 patients with PAD. Fifty healthy age-matched
controls will be participate in one baseline gait assessment for comparison purposes. Both
groups between 40-85 years old.
Interventions and Evaluations Biomechanics evaluations: Patients with PAD will complete a
biomechanics evaluation at baseline, following three months of control (standard of care),
and following three months of AFO intervention. The evaluation will include measurement of
walking distances, gait function, physical activity, quality of life, energy cost, muscle
morphometrics, muscle activity, muscle oxygenation, and muscle strength and endurance while
walking with and without the AFO. Healthy controls will be assessed during one baseline
collection only and their participation in the study will then be finished.
Feasibility interview: All patients with PAD will participate in feasibility interviews that
will assess acceptability, demand, implementation, and practicality. Interviews will occur
1.5 months and following completion of the AFO intervention (not the control arm).
AFO and Control (standard of care) Intervention: Patients will wear an off-the-shelf, carbon
composite AFO that is adjusted to fit for three months. The patients will be asked to wear
the AFO at all times except when they are in bed or showering/bathing. The instructions given
to the patients about walking will be to follow the instructions from their doctor regarding
risk factor management and exercise. The intervention order will be randomized and all
subjects will participate in both arms.
Description:
Peripheral artery disease (PAD) is a common cardiovascular disease manifesting from
atherosclerotic blockages in the arteries of the legs. The most prevalent symptom of PAD is
intermittent claudication, defined as pain or discomfort in the legs that is produced by
physical activity and is relieved only through rest. PAD results in significant functional
limitations such as slower walking velocity and an overall sedentary lifestyle. Prior
research has documented significant deficits in gait biomechanics; specifically, an inability
of the ankle plantar flexors to generate normal torque and power. Furthermore, insufficient
blood flow was not found to be the only mechanism contributing to gait dysfunction in
patients with PAD, but the affected muscle also demonstrates a myopathy that prevents normal
leg function in these patients. Thus, treatment must consider muscular function and
hemodynamics to improve function and increase activity levels. Supervised treadmill walking
exercise is an effective treatment for increasing the distances patients with PAD can walk.
However, there is a critical treatment gap for individuals whose disease presentations
warrant a non--operative treatment plan but lack the motivation, time, access and monetary
resources for supervised therapy. An ankle--foot orthosis (AFO) to offset ankle plantar
flexor torque and power deficiency is a novel approach to increase the walking distances and
physical activity levels in those with PAD. Made of a carbon-- composite material, AFOs are
adjustable, affordable and could be prescribed and worn long--term to overcome the reduced
propulsion and improve walking economy. The spring--like properties of carbon--composite AFOs
allow energy storage at weight acceptance and return at the point of toe off, when the ankle
plantar flexors are supposed to propel into the next step. Improvements in ankle kinetics and
angular momentum have been reported by using an AFO with stroke, and other neuromuscular
disorders affecting the legs. However, AFOs are typically worn for foot drop, and have never
been implemented in patients with PAD to improve forward propulsion. Pilot work has shown
that walking with an AFO instantly increases the initial and absolute walking distances in
patients with PAD as much as pharmacotherapy for six months. An AFO addresses both the
myopathy and low blood flow problems associated with claudication. Mechanical force from the
AFO compensates for the insufficient propulsion force of the myopathic gastrocnemius muscles,
while at the same time decreasing blood flow demand and muscular stress effects of ischemia.
Thus an AFO allows patients to walk longer without pain or walk the distance needed to
complete daily activities with less stress to the affected leg, and may preserve/improve the
overall health of the PAD limb by lowering oxygen demands to PAD muscle and effort induced
ischemia and stress.
Hypothesis: An AFO improves walking performance in patients with PAD by reducing the energy
cost of walking and these improvements can be seen from the first time the patient uses the
AFO. Further, an AFO intervention improves walking performance by improving the muscular
function of patients' affected legs.
Specific Aim 1: Test the hypothesis that from its first use an AFO produces improvements in
walking performance of patients with PAD by decreasing the required muscle contribution and
energy cost of walking.
Specific Aim 2: Test the hypothesis that using an AFO for three months leads to progressive
improvements in walking performance, physical activity levels and quality of life of patients
with PAD and that these improvements correlate with improvements in the morphometric
measurements, oxygenation levels, and muscle strength and endurance characteristics of the
affected legs. A crossover design will be used, in which half of subjects will complete a
three--month control period before, and half after, the AFO intervention.
Specific Aim 3: To determine the feasibility of a three month AFO intervention by examining
acceptability (satisfaction, intent to continue use), demand (actual use, perceived demand),
implementation (degree of use, success or failure of use, factors affecting use), and
practicality (effects, ability of participants to use AFO).
If the hypothesis is correct, the study will be the first to demonstrate that a simple,
accessible AFO device can rapidly improve functional status and quality of life in patients
with PAD immediately by decreasing the required muscular contribution and oxygen demands to
PAD muscle. Additionally, Aim #2 will evaluate the long--term effects of wearing an AFO on
functional status and quality of life. Aim #3 will help the investigative team ensure it is
feasible to implement the AFO in our target population. Detailed measures of mechanisms
related with walking performance, muscle contribution, physical activity, quality of life and
how these mechanisms change after wearing the AFO for three months will provide the evidence
required to implement an AFO therapy that will improve functional status and quality of life
in individuals with PAD.