Modelling thermoregulation for prosthetic design

Conventional manufacture of prosthetic sockets is artisanal, relying on limited objective data, which often leads to discomfort and tissue damage. Thermal discomfort is a key concern identified by amputees, particularly in hot climates. Despite this, it has had little research attention. This research increases knowledge of the body's heat transfer mechanisms and the effect of amputation and wearing a prosthesis on heat transfer and thermal discomfort through reviewing literature, running a clinical study with amputees and developing a computational bioheat model. A questionnaire on discomfort, completed by 42 amputees in Bangalore, found heat and perspiration in the prosthetic socket were the most prevalent causes of discomfort. Skin temperatures and thermal discomfort measurements were collected from 30 lower-limb prosthesis users during exercise. After exercise, thermal discomfort was greater on the amputated leg, despite the skin on both legs cooling. The discomfort might signal that the heat generated by the muscles in the residual limb during exercise is stored in the muscles. To explore the effect of the environment on muscle temperatures during exercise and post-exercise recovery, a cylindrical isolated-segment bioheat model of the thigh was developed in COMSOL Multiphysics and compared to empirical data of muscle temperatures. This model is the first to use finite element analysis to determine temperature distributions through the thigh during exercise and post-exercise recovery. It showed that thermal responses of individuals are varied and complex. From this understanding of the temperature responses of a healthy leg, the possible effects of amputation and prosthesis-use are discussed. The model increases knowledge of the heat transfer factors to consider in developing user-specific prosthetic sockets that reduce the body's thermal load. The feasibility of integrating simulations, such as this model, with computer-aided design and 3D printing technology to improve customisation of prosthetic sockets was assessed by systematically reviewing the effectiveness of 3D printing prosthetics and other medical devices. The technology shows promise for supporting data-driven prosthetic socket design and manufacture but lacks research and clinical validation.