Ankle–foot orthosis with dorsiflexion resistance using spring-cam mechanism increases knee flexion in the swing phase during walking in stroke patients with hemiplegia

Abstract

BackgroundAnkle–foot orthoses with plantarflexion resistance (AFO-Ps) improve knee flexion in the stance phase on the paretic side in patients with hemiparesis. However, AFO-Ps decrease ankle power generation in the late stance phase and do not improve the knee flexion in the swing phase based on insufficient push-off at the late stance, resulting in lower toe clearance. Research questionThis study sought to investigate the effect of an AFO with dorsiflexion resistance, which was implemented by our developed device with spring–cam mechanism attached to the AFO-P (Gait Solution; Pacific Supply Co., Ltd., Japan), on kinetics and kinematics in the lower limb during gait in patients with hemiparesis. MethodsEleven patients with hemiparesis due to stroke walked on a 7-m walkway at a self-selected comfortable pace in the following conditions: (a) walking using the AFO-P with the proposed device with a spring–cam mechanism (AFO-PCAM), (b) walking using the AFO-P without our device (AFO-P), and (c) walking using no device (barefoot condition). Gait kinematics and kinetics were collected using a three-dimensional motion analysis system and four ground-reaction force plates. Changes in all parameters from the barefoot to AFO-PCAM and AFO-P conditions were compared using the Wilcoxon signed-rank test. ResultsIn the AFO-PCAM condition, decrease in the maximum ankle power generation in the late-stance phase was significantly smaller than that in the AFO-P condition (p = 0.041). We noted a significant higher change in knee flexion in the paretic swing phase in the AFO-PCAM condition relative to that in the AFO-P condition (p = 0.016). The effect size for the comparisons of change was large (r ≧ 0.5). SignificanceOur device facilitated the realization of the ankle plantarflexion power in the late-stance phase because of dorsiflexion resistance, increasing the knee flexion angle during the swing phase.