Investigation of Wear and Wear Particles from Shelf-Aged Crosslinked UHMWPE under Different Contact Pressures

Abstract

The wear particles generated from ultra-high molecular weight polyethylene (UHMWPE) are considered as the main reason to cause the osteolysis and aseptic loosening related to the failure of the artificial joint. This paper investigated the effect of radiation dose and contact pressure on the wear rate and wear particles of shelf-aged crosslinked UHMWPE using a multi-directional pin-on-plate wear tester. Scanning electron microscopy (SEM) and necessary software were used for quantitative analysis of wear particles. Results showed that for the shelf-aged crosslinked UHMWPE, the surface region where exhibited a low oxidation level, still maintained very good wear resistance. The specific wear rate was decreased with the increase of radiation dose and contact pressure. Quantitative analysis results of wear particles from crosslinked UHMWPE showed that after the wear tests, the percentage volume of smaller particles, complexity, specific biological activity (SBA) index of wear particles and the functional biological activity (FBA) index were reduced with increasing radiation dose. The contact pressure did not obviously affect the complexity of wear particles from crosslinked UHMWPE but had a clear influence on wear rate, SBA index and FBA index, and the effect on the particle size distribution was getting weaker as the radiation dose increases.