Socket Material and Coefficient of Friction Influence on Residuum-Prosthesis Interface Stresses for a Transfemoral Amputee: A Finite Element Analysis

One of the main difficulties associated with the use of lower limb prosthesis is the perception of discomfort and pain in the residual limb, mainly due to poorly-fitted sockets. In this context, numerical simulations have performed a fundamental role in the search for successful fittings, contributing towards enhancement of the traditional iterative and labor-intensive fabrication process. This work aims to apply finite element modeling to simulate the socket-limb interface stresses for a transfemoral amputee during gait, and to investigate the effects of socket material and coefficient of friction on comfort and durability. The developed model was composed by socket, stump and femur geometries, and presented a loading scenario corresponding to the forces acting on the hip joint during a gait cycle. Several simulations were conducted, with varying design parameters, such that each configuration was analyzed in terms of prosthetic resistance to cyclic loading and distribution of contact pressures and frictional stresses. Carbon fiber sockets demonstrated greatest durability among the four tested materials, but it also induced a slight increase in the maximum contact pressure. As the coefficient of friction was incremented, contact pressures were reduced, and frictional stresses increased, with the values between 0.5 and 0.8 showing the best compromises.