Toward more intuitive prosthetic control: structured residual muscle training in transtibial amputees

Myoelectric control of lower-limb prostheses is challenging due to residual muscle co-contraction, inconsistent activation, and signal variability. Evidence regarding the efficacy of training interventions targeting residual muscle activation in transtibial amputees (TTAs) to enhance prosthetic control remains limited. This study investigated whether a 4-week structured training could improve residual muscle control in TTAs. Nine male unilateral TTAs were assigned to either (A) biofeedback training with daily home exercises or (B) home exercises alone. Biofeedback sessions provided real-time surface electromyography (EMG) feedback on Tibialis Anterior, Gastrocnemius, and Peroneus Longus activity. Performance was evaluated at baseline and post-intervention using contraction accuracy (root mean square error), signal stability (time outside bounds), and selective muscle activation (co-contraction index). Despite substantial inter-individual variability, participants demonstrated overall improvements in accuracy, stability, and selective muscle activation, irrespective of group. These findings suggest that consistent home-based training alone can induce rapid neuromuscular adaptation with measurable improvements in residual muscle control. However, this study was exploratory in nature and not powered to detect small between-group differences. Inter-individual variability highlighted the influence of baseline control and amputation etiology on outcomes, and one participant reported adverse neuropathic pain, underscoring the need to screening for neuropathic susceptibility, especially in individuals with prior neuroma or chronic phantom limb pain. Overall, structured EMG-based training improved residual muscle control in TTAs. These findings support the potential of EMG-guided interventions to foster more intuitive and reliable prosthetic use and to inform future rehabilitation protocols.