Influence of Pelvis Width and Leg Length on the Wear Behavior of UHMWPE Hip Cup

Abstract

Total hip joint replacement considered one of the success sections of the modern medicine, but still the wear of total hip prostheses is a significant clinical problem and this problem might be increasingly complex with adding the influence of pelvis width and leg length during the preclinical testing. This study aims to analyze the effect of the leg length (femur and tibia) and the pelvis width on the wear behavior of ultra-high molecular weight polyethylene (UHMWPE) hip cup. The experiments have been carried out on a total leg joint’s simulator (TLJS), which was particularly designed for this purpose according to ISO 14242-1 standard. The TLJS consists of three units: leg components (femur, tibia, and foot), quick-return mechanism, and cam mechanism were used to reproduce the flexion–extension and external–internal movement, respectively, and upper body was used to stimulate the pelvis construction and applied load. The wear behavior of the tested cups (in weight loss form) was evaluated under dry lubricating conditions, and then the wear mechanism of worm cups was examined by using scanning electron microscopy. The results showed that the length of the femur, tibia, and pelvis width have a positive effect on the wear rate of the tested cups due to flexion and pelvic moment which is resulted by the ground reaction force and pelvic rotation force.