Unloading shoes for intermittent claudication: a randomised crossover trial

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 2 weeks, with the instruction to wear them for at least 4 h 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 68 years, mean ankle-brachial index 0.54) completed both assessment visits. On average, the 6-min walk distance was 11 m greater when participants wore the control shoes (95% CI -5 to 26), whereas mean pain-free walking distance was 7 m 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 0.2 Nm/kg, 95% CI 0.0 to 0.3) and peak ankle power generation (mean difference 0.6 W/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.