Unloading shoes for intermittent claudication: A randomised crossover trial

Abstract

Background: The purpose of this study was to assess the functional effects and acceptability of rocker-soled shoes that were designed to relatively "unload" the calf muscles during walking in people with calf claudication due to peripheral arterial disease. Methods: In this randomised AB/BA crossover trial, participants completed two assessment visits up to two weeks apart. At each visit, participants completed walking tests whilst wearing the unloading shoes or visually-similar control shoes. At the end of the second visit, participants were given either the unloading or control shoes to use in their home environment for 2weeks, with the instruction to wear them for at least 4h every day. The primary outcome was 6-min walk distance. We also assessed pain-free walking distance and gait biomechanical variables during usual-pace walking, adverse events, and participants' opinions about the shoes. Data for continuous outcomes are presented as mean difference between conditions with corresponding 95% confidence interval. Results: Thirty-four participants (27 males, mean age 68years, mean ankle-brachial index 0.54) completed both assessment visits. On average, the 6-min walk distance was 11m greater when participants wore the control shoes (95% CI -5 to 26), whereas mean pain-free walking distance was 7m greater in the unloading shoes (95% CI -17 to 32). Neither of these differences were statistically significant (p=0.18 and p=0.55, respectively). This was despite the unloading shoes reducing peak ankle plantarflexion moment (mean difference 0.2Nm/kg, 95% CI 0.0 to 0.3) and peak ankle power generation (mean difference 0.6W/kg, 95% CI 0.2 to 1.0) during pain-free walking. The survey and interview data was mixed, with no clear differences between the unloading and control shoes. Conclusions: Shoes with modified soles to relatively unload the calf muscles during walking conferred no substantial acute functional benefit over control shoes. Trial registration: Clinicaltrials.gov, Trial Registration Number: NCT02505503 , First registered 22 July 2015.