A Non-Invasive Method of Muscle Force Estimation of a Lower Limb with a Partial Foot Amputation

Background and Aim: Previous gait analysis of partial foot amputee subjects has focussed on quantification of joint angles, moments and powers without quantifying muscle forces. This research aimed to develop a subject-specific musculoskeletal model of a partial foot amputee gait to quantify muscle forces of a lower limb affected by a mid-foot amputation during walking non-invasively. Technique: First, a musculoskeletal model of the subject was developed. Secondly, the time history of joint moments were predicted by the model and compared with those calculated by a non-musculoskeletal model to verify the model calculation and thirdly, the time history of muscle forces were predicted by the musculoskeletal model of the subject using collected kinematic and kinetic data of the subject during walking. The timings of generated muscle forces and EMG signals were used for the evaluation of muscle forces predicted by the musculoskeletal model. Discussion: The timing of muscle forces and EMG signals of muscles indicated that the model predictions for individual muscle forces of the lower limb were reliable and the musculoskeletal model quantified the muscle forces to some degrees of confidence. Clinical Relevance: Further research is required to understand the effects of partial foot amputation on muscle adaptation during walking, which should help to inform new surgical methods of tendon transfer designs of prosthetic/orthotic interventions, with greater focus on improving the gait patterns.