Model-Driven Design of Electrical Stimulation Therapy Improves Gait Dynamics in Individuals With Limb Amputations

OBJECTIVE: Amputation is a life-changing condition that leads to impaired gait, chronic pain, and progressive musculoskeletal deterioration. Functional electrical stimulation (FES) has the potential to improve mobility and manage pain; yet, clinically, prescribing this therapy largely depends on clinician experience, which limits its efficacy. This study aimed to design and evaluate the first FES gait rehabilitation therapy for individuals with limb amputation using musculoskeletal modelling techniques. METHODS: We integrated musculoskeletal modelling with optimal control simulations to identify stimulation strategies capable of modulating joint loading during gait. An in-silico trial was conducted to determine target muscles for stimulation, followed by an in-vivo gait assessment to evaluate FES-assisted walking performance. RESULTS: The in-silico study showed that stimulating the vasti muscles in the amputated limb provided mechanical advantages by modulating internal loading. Experimental gait analysis further confirmed these findings, demonstrating that the model-driven design produced favourable biomechanical effects, including reduced peak knee contact forces in the intact limb and increased vasti muscle forces in the amputated limb during FES-assisted walking. CONCLUSION: Stimulating the vasti muscles in the amputated limb can enhance gait dynamics in individuals with transtibial amputation. SIGNIFICANCE: This study, which combines in-silico therapy design with in-vivo validation, paves the way for evidence-based digital tools to support effective FES-based gait rehabilitation and has potential to be extended to broader clinical populations with gait impairments arising from neurological or musculoskeletal conditions.