Task-specific ankle robotics gait training after stroke: a randomized pilot study

Abstract

Background: An unsettled question in the use of robotics for post-stroke gait rehabilitation is whether task-specific locomotor training is more effective than targeting individual joint impairments to improve walking function. The paretic ankle is implicated in gait instability and fall risk, but is difficult to therapeutically isolate and refractory to recovery. We hypothesize that in chronic stroke, treadmill-integrated ankle robotics training is more effective to improve gait function than robotics focused on paretic ankle impairments.

Findings: Participants with chronic hemiparetic gait were randomized to either six weeks of treadmill-integrated ankle robotics (n = 14) or dose-matched seated ankle robotics (n = 12) videogame training. Selected gait measures were collected at baseline, post-training, and six-week retention. Friedman, and Wilcoxon Sign Rank and Fisher's exact tests evaluated within and between group differences across time, respectively. Six weeks post-training, treadmill robotics proved more effective than seated robotics to increase walking velocity, paretic single support, paretic push-off impulse, and active dorsiflexion range of motion. Treadmill robotics durably improved gait dorsiflexion swing angle leading 6/7 initially requiring ankle braces to self-discarded them, while their unassisted paretic heel-first contacts increased from 44 % to 99.6 %, versus no change in assistive device usage (0/9) following seated robotics.

Conclusions: Treadmill-integrated, but not seated ankle robotics training, durably improves gait biomechanics, reversing foot drop, restoring walking propulsion, and establishing safer foot landing in chronic stroke that may reduce reliance on assistive devices. These findings support a task-specific approach integrating adaptive ankle robotics with locomotor training to optimize mobility recovery.

Clinical trial identifier: NCT01337960. https://ichgcp.net/clinical-trials-registry/NCT01337960?term=NCT01337960&rank=1.

Keywords: Hemiparetic gait; Locomotor training; Robotics; Stroke; Task-specific training.

Figures

Fig. 1

CONSORT flow diagram

Fig. 2

a Group data (mean ± SE) from 1-min unassisted treadmill trials at self-selected speed showing paretic peak swing (PSW) and initial contact angles (AIC) at baseline (“PRE”), 6-week post-test (“POST”), and 6-week retention (“RETN”) time points. b Group data (mean ± SE) from 1-min unassisted treadmill trials at self-selected speed showing frequency of heel-first ground contact at baseline (“PRE”), 6-week post-test (“POST”), and 6-week retention (“RETN”) time points. c Motor learning profiles in unassisted paretic peak swing angle across 18 training sessions from five TMR subjects whose training targeted foot drop. Each profile conforms to a power-law function that is fitted to the peak swing angle averaged across individual steps during a 1-min unassisted trial at self-selected speed, across visits. The profiles are representative of the spectrum of different learning rates in swing clearance