Assisting Sit-To-Stand Through Event-Based Electrical Stimulation of Trunk Control: A Preliminary Study

Independence afforded by functional mobility is invaluable yet inaccessible for those with spinal cord injury (SCI). Regaining mobility skills like sit-to-stand (STS) promotes independence and recovery. Previously, functional electrical stimulation (FES) of leg muscles and exoskeletons have assisted STS, but limitations exist. FES causes fatigue and spasms while exoskeletons cannot activate muscles directly nor suit those with poor trunk control. Thus, hybrid FES exoskeletons are promising but rarely target trunk muscles. This study examined FES of erector spinae for STS assistance with a wearable lower limb exoskeleton. Healthy and SCI participants performed STS with and without stimulation. Joint kinematics quantified STS performance. SCI hip motion differed, demonstrating excessive trunk flexion and slow extension compared to healthy participants. Knee kinematics were similar between groups. Stimulation intensified SCI trunk flexion despite initiating post-extension. Further investigation of SCI STS patterns and stimulation effects is warranted. Overall, functional electrical stimulation of erector spinae appears feasible and alters SCI trunk motion during STS in ways that may promote stability and independence. Ultimately such hybrid FES exoskeletons may help transform mobility and independence for those with SCI.