Improving walking in peripheral artery disease using specially designed assistive shoes

Omaha Va Medical Center, Omaha NE

Investigators

Abstract

The long-term goal of this project is to improve mobility, functional independence, and quality of life in patients with peripheral artery disease (PAD) by using specially designed assistive shoes. PAD is a manifestation of systemic atherosclerosis producing blockages in the leg arteries, resulting in insufficient blood flow to the lower extremities. Limb ischemia from PAD is the most common disorder treated within the vascular surgical service of the Omaha Veterans Affairs Medical Center. PAD also accounts for one-third of the operations performed nationwide in the VA. Walking induced muscle pain known as intermittent claudication is the most common PAD symptom. Claudicating patients with PAD walk slower, have reduced quality of life and lose independence in performing activities of daily living. We have identified consistent deficits of the ankle plantarflexors to effectively push-off during walking. Currently, there is a critical treatment gap for patients whose disease presentation does not warrant an operative approach, but who desire to restore their functional independence and walking ability. Specially designed assistive shoes (carbon fiber: CF; spring-loaded: SL) with specific mechanical properties to absorb and release energy, have been shown to promote push-off efficiency in walkers and runners. These shoes may lead to improved push-off in populations with reduced ankle push-off capacity, but this has not been tested yet. This work proposes to evaluate patient preferences in terms of using assistive shoes and whether these shoes improve walking performance in claudicating patients with PAD. We hypothesize that assistive shoes (CF and SL) will lead to improved walking performance in patients with PAD as compared to standard shoes. We also hypothesize that subject reported preference of assistive shoes (CF and SL) will be positive based on comfort, fatigue, ease of walking, and feasibility. These hypotheses will be tested by the following three specific aims: Aim 1: Determine the acute improvement in walking performance (claudication walking distances, vertical ground reaction force, and muscle oxygenation) in patients with PAD while using their standard shoes versus the assistive shoes. Aim 2: Determine the subject-reported preference of assistive shoes. Aim 3: Determine the progressive improvements in physical activity, quality of life, and walking distance after a three-month assistive shoe intervention. Twenty patients with PAD will be recruited for Aims 1 and 2. For Aim 1, each subject will walk on a pressure instrumented treadmill while performing a progressive treadmill test with a near infrared spectroscopy sensor on the calf for each shoe condition: i) standard, ii) CF, and iii) SL. Walking performance will be evaluated in terms of claudication walking distances, vertical ground reaction force, and muscle oxygenation. All outcomes will be compared across these three types of shoes. Aim 2 will primarily focus on qualitative measurements of subject reported preference to identify whether assistive shoes are feasible for patients with PAD to use. Visual-analog scales, rate of perceived exertion, and interviews will be used to assess comfort, fatigue, intensity, and feasibility after each condition of Aim 1. Five patients from Aims 1 and 2 who are satisfied with CL and another five who are satisfied with SL, will be recruited for Aim 3. Patients will wear the assistive shoes of their choice for regular daily use for three months as a conservative intervention. Physical activity, quality of life, and walking distances will be assessed prior to the start of the intervention and after three months of intervention. Overall, our aims will demonstrate feasibility and acceptability of assistive shoes in patients with PAD. Results will support a full clinical trial, and guide necessary intervention length and potential rehabilitation recommendations.