Reducing wear debris and increasing lower-limb amputees' comfort by optimizing prosthetic socket design using local contact pressure relief and implementing appropriate holes

Abstract

Maintaining a comfortable fit in prosthetic socket for trans-tibial amputees (TTA) using design of experiment (DOE) and finite element model (FEM) to implement relief areas and holes in socket structure are important goals to help ensure better pressure distributions and successful rehabilitation. Design and fit of socket rely on patient acceptance and comfort. Sixteen sockets designed with different levels of reliefs and holes were investigated by Finite Element Model (FEM) and Design of Experiment (DOE) for flexibility and pressure distribution using ultra high molecular weight polyethylene (UHMWPE) and polyamide 6 (PA6) or Duraform then compared to conventional socket without any compliance. The purpose of this study was to assess performance of sockets with compliant features integrated into the socket wall to relieve in-socket pressure, increase flexibility and patient comfort during transtibial amputee gait. Reducing thickness at designated areas and hole implementation between the Patellar Tendon (PT) and Distal Tibia (DT) would decrease stiffness and increase prosthesis range of motion where flexibility is needed without compromising mechanical efficiency and the structural integrity of the socket. Different materials sockets 3 of each obtained by FEM/DOE analysis were manufactured and used by six amputees of the same age groups to measure the level of comfort and check the worn surfaces using scanning electron microscopy (SEM) and amputee performances after one year of usage. SEM and optical images were compared. The calculated stiffness of the two compliant sockets with holes are much less than the conventional sockets; they were more comfortable and showed significant decrease in wear debris over the course of the trial period.