Effects of Biological Lubrication on the Morphology of UHMWPE Wear Particles Generated With Surface Textures

Abstract

Osteolysis induced by ultra-high molecular weight polyethylene (UHMWPE) wear particles has emerged as a critical failure mechanism of artificial joints. Many researchers have performed cell culture studies or animal tests to investigate the UHMWPE particles induced immunological responses. However, the effect of size and shape remains elusive. This is partly because of the difficulty in obtaining UHMWPE wear particles with specific sizes and shapes for bioactivity tests. Previously, we have shown the feasibility of producing narrowly distributed UHMWPE particle sizes and shapes by rubbing UHMWPE pins against textured surfaces [1]. The correlations between the surface texture dimensions and the size and shape of wear particles generated in water have been obtained [2]. In addition, this novel technique of UHMWPE particle generation enables the investigation of the effects of UHMWPE particle size and shape on bioactivity. It is concluded that the elongated particles and the particles which can be engulfed by macrophage cells induced stronger immunological responses [3]. Thus, it is possible to enhance the life of total joint replacements by reducing the production of the most toxic particle populations in terms of size and shape. Our idea is to apply surface textures on the articulating surface of joint implant in order to control the size and shape of UHMWPE wear particles. While maintaining a low wear rate of UHMWPE parts, further reduction of the most “toxic” particles released into human body shall prevent particle-induced osteolysis.