Predictive prosthetic socket design: part 1\u2014population-based evaluation of transtibial prosthetic sockets by FEA-driven surrogate modelling

P R Worsley,M Browne,J W Steer,A S Dickinson

doi:10.1007/s10237-019-01195-5

P R Worsley, M Browne + Show 2 more

Open Access

https://doi.org/10.1007/s10237-019-01195-5

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Abstract

It has been proposed that finite element analysis can complement clinical decision making for the appropriate design and manufacture of prosthetic sockets for amputees. However, clinical translation has not been achieved, in part due to lengthy solver times and the complexity involved in model development. In this study, a parametric model was created, informed by variation in (i) population-driven residuum shape morphology, (ii) soft tissue compliance and (iii) prosthetic socket design. A Kriging surrogate model was fitted to the response of the analyses across the design space enabling prediction for new residual limb morphologies and socket designs. It was predicted that morphological variability and prosthetic socket design had a substantial effect on socket-limb interfacial pressure and shear conditions as well as sub-dermal soft tissue strains. These relationships were investigated with a higher resolution of anatomical, surgical and design variability than previously reported, with a reduction in computational expense of six orders of magnitude. This enabled real-time predictions (1.6 ms) with error vs the analytical solutions of < 4 kPa in pressure at residuum tip, and < 3% in soft tissue strain. As such, this framework represents a substantial step towards implementation of finite element analysis in the prosthetics clinic.

Highlights

The prosthetic socket provides the critical attachment between the residual limb following amputation and the prosthetic device
New data points from the regions of interest (ROI) surrogate models were evaluated in 1.6 ms, representing an increase in solver speed of ∼ 106 times
This study presents the first use of a parametric, real-time, finite element analysis (FEA)-driven model to explore the relationship between residual limb morphology, soft tissue compliance and prosthetic

Summary

Introduction

The prosthetic socket provides the critical attachment between the residual limb following amputation and the prosthetic device. To ensure a good socket fit, clinicians perform a series of geometrical modifications to the captured shape of the individual’s residual limb, known as rectification, targeting optimal load transfer. This involved physical modification of a positive plaster mould. Digital technologies are becoming more prevalent within the clinical community (Whiteside et al 2007; Karakoç et al 2017) This approach involves using a surface scanner to digitise the limb’s surface shape, performing the patient-specific rectifications in a CAD environment and manufacturing a mould to form the socket within a central fabrication facility (Saunders et al 1985; Oberg et al 1989; Sanders et al 2007)

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