Stress Analysis of a Patient-specific Socket Design during Gait Cycle

Abstract

Transtibial amputation is one of the common surgical procedure involved removal of lower limbs specifically below the knee. The need of amputation was caused by major accidents or diseases. Prosthetic socket was an important part as it kept the residual limb in place. It should allow amputee to perform daily activities without caused any pains. Most amputees reviewed the socket’s design caused pain on their residual limb. This project was purposed to analyse the pressure distribution on the prosthetic socket design. Design of the socket was based on stump’s condition which verified from the hospitals. Autodesk Meshmixer software was used to remodel the socket design from 3D Computer Aided Design (CAD) data of real stump. Pressure sensors measured the pressure exerted due to contact between socket and stump. The measured pressure distribution was analysed according to the pressure tolerant and sensitive areas to avoid the uncomfortable pain. The simulation of socket design was simulated using Finite Element Method (FEM) in ANSYS Static Structural. FEM indicated the behaviour of the socket during static and dynamic condition. Then, prosthetic sockets were fabricated in-house manufacturing process based on Fused Deposition Modelling (FDM) technology using 2.85-mm filament of polyamide nylon (PA). Thus, the tensile properties of the nylon socket material were determined according to ASTM D638. The evaluated stress was 11.30 MPa at the mid-stance that proved the material was highly strength to support the load. The structural integrity of the complete prosthesis socket should be investigated according to ISO 10328 for future improvement.