Clinical usability and functional outcomes of a lightweight robotic orthosis (HKAFO) in chronic stroke patients with hemiplegic gait: a pilot study

Gait impairment after stroke limits independence. Powered orthoses may augment task-specific over-ground practice, although clinical uptake is constrained by usability. We evaluated a powered hip–knee–ankle–foot orthosis (HKAFO) for functional outcomes and usability in ambulatory adults with chronic post-stroke hemiparesis. In a prospective multicenter single-arm pilot, 15 participants completed six supervised over-ground HKAFO sessions across three weeks (40 min per session). Pre-specified clinical outcomes were the Berg Balance Scale (BBS), Dynamic Gait Index (DGI), and Timed Up and Go (TUG). Short-distance walking (6-minute walk test [6MWT], 10-meter walk test [10MWT]) was assessed with and without the device. Analyses used paired tests and a two-way repeated-measures ANOVA with within-subject factors Time (pre, post) and Condition (with HKAFO, without HKAFO). BBS increased by 3 points (45 [36–49] to 48 [42–52], p = 0.002), DGI by 2 points (19 [13–21] to 21 [18–23], p = 0.004), and TUG decreased by 1.98 s (16.80 [11.35–21.65] to 14.82 [9.85–20.39], p = 0.014). With the HKAFO, 6MWT distance rose (194.1 to 220.0 m, p = 0.006) and 10MWT speed increased (0.57 to 0.71 m/s, p = 0.005), whereas unassisted walking changed little over three weeks. Two-way repeated-measures ANOVA confirmed a main effect of Time and a strong main effect of Condition for 6MWT (Time: F(1,14) = 10.34, p = 0.006, ηp²=0.425; Condition: F(1,14) = 33.93, p < 0.001, ηp²=0.708), with a non-significant Time×Condition interaction (p = 0.090). For 10MWT cadence the interaction approached significance (F(1,14) = 4.23, p = 0.059, ηp²=0.232); for 10MWT speed and time, interactions were not significant, while the Condition main effect remained significant (speed: F(1,14) = 17.15, p = 0.010; time: F(1,14) = 7.46, p = 0.016). Participants reported perceived stability benefits alongside burdens related to weight, donning and doffing, and operation. Across six sessions, HKAFO-assisted over-ground practice was associated with improved balance and functional mobility and with faster short-distance gait during device-assisted walking, with limited short-term transfer to unassisted gait. The two-condition design delineated a device-dependent profile. Confirmatory randomized trials with longer follow-up and usability-focused refinement are warranted.