Comparing Ankle Dorsiflexion-Only, Hip Flexion-Only, and Combined Hip-Ankle Assistance During Simulated Foot Drop Gait.

Abstract

This study experimentally evaluated whether coordinated multi-joint assistance within a single-limb soft exosuit produces broader swing-phase kinematic modulation than isolated ankle or hip assistance under a foot-drop-like perturbation. Ten healthy male adults walked on a treadmill at 4.0 km/h with a 2-kg distal mass on the dorsum of the foot to simulate a unilateral foot-drop clearance challenge. Four conditions were tested: loaded walking without assistance (LW), hip-only (HIP), ankle-only (ANK), and combined hip-ankle (MULTI) assistance delivered via a unilateral cable-driven exosuit. Three-dimensional marker trajectories were recorded using motion capture. Foot-clearance metrics and sagittal-plane hip, knee, and ankle kinematics were analyzed using repeated-measures ANOVA and statistical parametric mapping (SPM). Compared with LW, both ANK and MULTI produced significant increases in maximum toe height and minimum toe clearance during mid-swing, and both exceeded HIP in minimum toe clearance. MULTI additionally produced a significant increase in foot contact angle at initial contact relative to LW. MULTI did not further increase minimum toe clearance or contact angle over ANK, but uniquely induced significant late-swing alterations in both hip and ankle sagittal kinematics; knee kinematics were unaffected by any condition. Coordinated multi-joint assistance yielded broader swing-phase kinematic modulation than isolated joint assistance, with its distinctive contribution lying in simultaneous proximal and distal control rather than further peak-clearance gains. These findings provide biomechanical evidence supporting multi-joint soft exosuit strategies for swing-phase foot clearance in foot-drop-like gait, while clinical translation remains to be established.