Characterization of a variable friction shoe for foot drop and pilot test with stroke patients

Foot drop increases the risk of inadvertent ground contact during the swing phase of gait, which often leads to trips and falls. This study presents the design, characterization, and pilot trial of a variable friction (VF) shoe designed to reduce this risk by providing low friction during inadvertent ground contact and high-friction during stance and toe-off. Characterization results from bench-top testing demonstrated a consistent, load-dependent increase in coefficient of friction (CoF) across multiple surfaces that were maintained over year-long simulated wear. A healthy human-subject trial demonstrated reduced frictional scuff forces and trip events for the VF shoe versus conventional footwear. Three post-stroke patients completed an AB crossover take-home pilot trial where patients wore (A) the VF shoes for 2-weeks and (B) an ankle foot orthosis (AFO) with normal sneakers for 2-weeks. Pilot results showed promise: after the period wearing VF shoes, all subjects increased their 6-minute walk test (6MWT) distance and their 10 meter walk test (10MWT) speed. Results were mixed after the AFO arm. Together, these findings demonstrate the VF shoe's load-dependent frictional behavior, mechanical durability, and preliminary clinical feasibility, supporting its potential as a strategy to mitigate slip‑ and trip-related risk in individuals with foot drop.