Improving Walking in Peripheral Artery Disease

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. The investigators 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. The investigators hypothesize that using assistive shoes (either CF or SL, based on their preference) for three months will lead to improved walking performance in patients with PAD. The investigators also hypothesize that the subject-reported preference of assistive shoes (CF versus SL) will be positive based on comfort, fatigue, ease of walking, and feasibility at the baseline session. Two hypotheses will be tested by the following three specific aims:

Aim 1: Determine the subject-reported preference of assistive shoes at the Baseline visit.

Aim 2: 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. Aim 1 will primarily focus on qualitative measurements of subjects' reported preferences to identify which assistive shoes are feasible for patients with PAD to use during the three months of intervention. Visual-analog scales, rate of perceived exertion, and interviews will be used to assess comfort, fatigue, intensity, and feasibility after each shoe condition of Aim 1. Patients will wear the preferred 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, the aims will demonstrate the 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.

Inclusion criteria

At entry into the study, all patients must:

• be able to give written, informed consent
• demonstrate positive history of chronic claudication
• have an ankle brachial index < 0.90 at rest
• have a stable blood pressure regimen, stable lipid regimen, stable diabetes regimen and risk factor control for 6 weeks

Exclusion criteria

Any potential subjects will be excluded if they have:

• rest pain or tissue loss due to peripheral artery disease (Fontaine stage III and IV)
• acute lower extremity ischemic event secondary to thromboembolic disease or acute trauma
• walking capacity significantly limited by conditions other than claudication including leg (joint/musculoskeletal, neurologic) and systemic (heart, lung disease) pathology