Amputation can result in a loss of sensory feedback and alterations in gait biomechanics, including co-contractions of antagonist muscles near the knee and ankle, reduced pelvic obliquity range of motion, and pelvic drop. With that in mind, researchers conducted a case study to examine the effects of spinal cord stimulation (SCS) on muscle activity during walking in people with lower-limb amputations.
A participant with a transtibial amputation had SCS electrodes implanted percutaneously over the lumbosacral enlargement for 84 days. SCS was used during in-lab experiments to provide somatosensory feedback from the missing limb, relaying a sense of plantar pressure when the prosthesis was in the stance phase of the gait cycle.
The researchers used electromyography (EMG) to record muscle activity from the residual and intact limbs, and 3D motion capture to measure pelvic obliquity and knee and ankle joint angles. EMG signals were also recorded during walking with and without SCS at early (day 30) and late (day 63) time points across the implant duration.
The study concluded that during walking, co-contraction of knee antagonist muscles was reduced following multiple sessions of SCS-mediated sensory restoration. The activation of the hip abductor muscle also increased activity during gait with SCS-mediated sensory restoration, which corresponded to an increase in pelvic obliquity range of motion and pelvic drop toward normal.
The case study, “Changes in muscle activation and joint motion during walking after transtibial amputation with sensory feedback from spinal cord stimulation,” was published in the Journal of Neural Engineering.
