The analysis and measurement of interface pressures between stump and rapid prototyping prosthetic socket coated with a resin layer for transtibial amputee

Abstract

This study is to verify the applicability of the newly-developed prosthetic socket fabricated by rapid prototyping (RP) machine and then coated with a layer of resin to reinforce the flexural strength. This article aims to simulate and to measure the distribution of interface pressures on pressure tolerant (PT) and pressure relief (PR) areas of stump while amputee wearing a prosthesis and walking on a force platform. The results of comparison of the interface pressures between new type socket and conventional socket show that the RP socket could be made without using any plaster and the related information could be stored for further uses. The quasi-static method is introduced in finite element (FE) modeling to simulate amputee walking. From the results of simulation, it can evaluate whether the socket shape is acceptable or not. The verified socket model is then transferred to rapid prototyping machine to produce a required prosthetic socket. Moreover, coating a resin layer on the RP socket to reinforce its strength was proposed. To validate this new type of socket, the interface pressures were measured by attaching socket sensors on PT and PR areas of the specific stump before wearing the RP socket. The results of measurement and simulation of the pressure distributions of the resin-reinforced RP socket and the used socket are similar in the whole stance phase. Comparing to the used socket, the new type socket can bear more pressures at patella tendon. The FE analysis method is effectively to assist the shape modification of stump and socket can then be designed for the production using rapid prototyping machine.