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.