Real-time visual feedback affects peak propulsive horizontal force and metabolic cost in individuals with unilateral transtibial amputation during walking

Individuals with unilateral transtibial amputation (uTTA) using a passive-elastic energy storage and return (ESAR) prosthesis to walk have asymmetrical peak propulsive horizontal ground reaction force (hGRF) compared with nonamputees. Investigating and normalizing peak propulsive hGRF could be beneficial for individuals with uTTA, who experience a greater metabolic cost of walking and greater risk of developing secondary comorbidities compared with nonamputees. Use of the BiOM stance-phase battery-powered prosthesis can decrease peak propulsive hGRF asymmetry and the metabolic cost of walking compared with an ESAR prosthesis in people with uTTA. Moreover, providing individuals with uTTA feedback of peak propulsive hGRF could change peak propulsive hGRF and metabolic cost. Twelve participants with uTTA walked at 1.25 m/s while using an ESAR and BiOM prosthesis and were provided with visual feedback of peak propulsive hGRF. We found that when participants used the BiOM, affected leg (AL) peak propulsive hGRF increased by 0.014-0.017 body weight (BW), peak propulsive hGRF asymmetry decreased by 9.4-16.3 percentage points, and net metabolic power decreased by 0.16-0.26 W/kg compared with when they used an ESAR prosthesis. When participants were given visual feedback of peak propulsive hGRF, they increased AL peak propulsive hGRF and decreased peak propulsive hGRF asymmetry but incurred a greater metabolic cost when using either prosthesis. Our results suggest that future device designs should explore providing feedback of biomechanical variables and device control to the user during walking so that individuals with uTTA can more effectively use a powered prosthesis.<b>NEW & NOTEWORTHY</b> Individuals with unilateral transtibial amputation walked while using an energy storage and return prosthesis and the BiOM prosthesis and were provided with visual feedback of peak propulsive horizontal force (hGRF). Visual feedback increased affected leg peak propulsive hGRF and decreased peak propulsive hGRF asymmetry, but participants incurred a greater metabolic cost when using either prosthesis. Future device designs should explore biofeedback and device control to help individuals more effectively use a powered prosthesis.