Powered knee exoskeleton improves sit-to-stand transitions in stroke patients using electromyographic control

Millions of stroke survivors are affected by hemiparesis, resulting in difficulty or inability to move one side of their body. Hemiparesis severely impacts the ability of individuals to perform essential everyday activities, reducing independence and quality of life. Here we show that a powered knee exoskeleton that assists the affected knee joint using proportional electromyographic control significantly improves the ability to stand up from a seated position in eight stroke survivors. With the exoskeleton, stroke survivors stood up significantly faster (8.8% reduction in stand-up time), more symmetrically (13.7% increase in weight-bearing symmetry), and with less effort on their affected side (32% reduction in peak quadriceps muscle activation, 25% reduction in peak biological torque generation). The exoskeleton effectively supplemented the lack of strength in their affected knee, increasing the total knee torque by 59%, which more closely matched their non-affected knee. These results suggest that powered knee exoskeletons are a promising solution for enhancing stand-up ability, improving symmetry, reducing effort, and ultimately enhancing stroke survivors' mobility and quality of life.