A Pilot Study on the Short-Term Effects of an Electric Knee-Ankle-Foot Orthosis on Gait Performance and Physiological Cost Index in Patients With Hemiplegia: Influence of Initial Balance Ability Assessed by the Berg Balance Scale

Abstract

Gait impairment is one of the most disabling consequences of stroke and substantially limits functional independence. While traditional orthoses provide joint stabilization, they often restrict natural motion and lack adaptive support. This study is aimed at evaluating the short-term effects of an electric knee–ankle–foot orthosis (E-KAFO) on gait performance and energy efficiency in patients with hemiplegia and at assessing how baseline balance ability, measured using the Berg Balance Scale (BBS), influences outcomes. This pre–post intervention, nonrandomized study enrolled poststroke survivors (n = 22), who were stratified into high- (BBS > 45) and low- (BBS ≤ 45) balance groups (HBG and LBG, respectively). Participants underwent gait assessments under two conditions: body-powered condition (BP_C), to evaluate rehabilitation effects independently of the device, and E-KAFO_C, to assess short-term assistive efficacy immediately after device use. All assessments were conducted before and after a 3-week intervention comprising seven E-KAFO training sessions. The primary outcome was gait speed, measured using the 5-m walk test (5-mWT). The 3-min and 6-min walk tests (3-MWT and 6-MWT) and the physiological cost index (PCI) were also evaluated to assess gait endurance and energy efficiency. The 5-mWT and 3-MWT/6-MWT were performed in randomized order to minimize order-related bias. No standard rehabilitation-only control group was included. Assistive effects (E-KAFO_C) and rehabilitative effects (BP_C) were analyzed and reported separately. Two-way repeated measures analysis of variance was used to assess the effects of group, time, and their interaction. Significant improvements in gait speed and endurance were observed across both conditions, with the LBG showing greater relative gains postintervention. In the E-KAFO_C condition, the LBG demonstrated a 33.31% increase in 5-mWT speed and a 25.51% increase in 3-MWT distance. Notably, PCI decreased in both groups, although the reduction was significant only in the LBG. These findings underscore the distinction between the short-term assistive benefits of the E-KAFO and the rehabilitative improvements captured by BP_C outcomes, emphasizing that BP_C results serve as the primary indicator of rehabilitation effectiveness. Importantly, baseline balance ability assessed by the BBS influenced assistive and rehabilitative responses, supporting its relevance for patient stratification. Given the exploratory design and limited sample size, these findings are hypothesis-generating and require confirmation in larger randomized controlled trials.