Robotic Ankle Exoskeleton and Limb Angle Biofeedback for Assisting Stroke Gait: A Feasibility Study

Post-stroke gait is slow, energetically costly, and unstable. Rehabilitation is necessary to encourage, retrain, and assist proper gait mechanics in stroke survivors. Evidence indicates robotic ankle exoskeletons can improve gait outcomes in stroke survivors, however challenges remain with proper lower limb positioning for optimal receipt of the assistance. Biofeedback can be used to improve positioning of the limb for receipt of robotic ankle exoskeleton assistance. In this study, four stroke survivors used bilateral powered robotic ankle exoskeletons (Dephy Exoboots) and an innovative, custom-designed vibrotactile-audio biofeedback interface targeting trailing limb angle to test the hypotheses that each intervention alone improves gait outcomes over baseline, and when combined they improve outcomes over either intervention alone. Compared to baseline, we found increases in average paretic propulsive impulse during the biofeedback-only and exoskeleton-plus-biofeedback conditions. Biofeedback alone induced the greatest increase on average self-selected walking speed, and the combination of exoskeleton assistance and biofeedback increased speed more compared to the robotic exoskeleton-only condition. Our preliminary results indicate that biofeedback in combination with a robotic exoskeleton produces greater synergistic benefits on gait performance than the use of an exoskeleton alone.