Key considerations for finite element modelling of the residuum-prosthetic socket interface

Abstract

Study Design: Computational modelling Background: Finite element (FE) modelling has long been proposed to support the design of prosthetics sockets. However, there is minimal detail in the literature to inform practice in developing and interpreting these complex, highly non-linear models. Objectives: To identify recommendations for best practice in FE modelling of lower limb prosthetics, considering key modelling approaches and inputs. Methods: This study developed a parametric FE model using MRI data from a transtibial amputee. Sensitivity analyses were performed upon socket loading methods, socket-residuum interface parameters and soft tissue material models from the literature, to quantify their effect on the biomechanical response of the residual limb to a range of parameterised socket designs. Results: It was found that these variables had a marked impact on the predicted response of the FE model, especially with regards to the interfacial pressure and shear distribution. Conclusions: All modelling decisions should be justified biomechanically and clinically: - consider the effects of donning and interface friction to capture the shear stresses - use representative stiffness hyperelastic material models for soft tissues when using strain to predict injury; and - interrogate models comparatively, against a clinically-used control - justification of these modelling decisions within a clinical reference frame.