Concurrent multibody and Finite Element analysis of the lower-limb during amputee running

Lower-limb amputee athletes use Carbon fiber Energy Storage and Return (ESAR) prostheses during high impact activities such as running. The advantage provided to amputee athletes due to the energy-storing properties of ESAR prostheses is as yet uncertain. Conventional energy analysis methods for prostheses rely upon multibody models with articulating joints. Alternatively, Finite Element (FE) analysis treats bodies as a deforming continuum and can therefore calculate the energy stored without using these rigid-body mechanics assumptions. This paper presents a concurrent multibody and FE model of the femur, tibia, socket and ESAR prosthesis of a transtibial amputee athlete during sprinting. Gait analysis spatial data was used to conduct an offline simulation of the affected leg's stance phase in COMSOL Multiphysics. The calculated peak elastic strain energy of the prosthesis was 80J, with an overall RMSE of simulated marker displacement of 4.19 mm. This concurrent model presents a novel method for analyzing in vivo ESAR prosthesis behavior.