Generation of Wear Particles with Specific Size and Shape for Pre-Clinical Tests of Orthopaedic Implants

Osteolysis induced by ultra-high molecular weight polyethylene (UHMWPE) wear particles have been recognized as the major reason causing the failure of total joint implants. However, the detailed mechanism of osteolysis and bone resorption induced by wear particles leading to the loosening of the total joint replacement is still not clear. To investigate the effects of size and shape of particles on biological responses, particles with controlled sizes and shapes are needed. This paper describes a novel technique where controlled size and shape of UHMWPE wear particles can be generated through articulating UHMWPE against a textured surface. With appropriate surface-texture design, UHMWPE particles can be generated with desired sizes and shapes. The distribution of the particles, due to the surface-texture control, is quite narrow. The production rate of UHMWPE wear particles is relatively high so that it is feasible to provide sufficient wear particles for pre-clinical cell-culture or animal tests. In addition, a novel inverted macrophage cell culture system has been developed to investigate the UHMWPE wear particles induced immunological responses. These newly developed procedures can assist on further understanding of the mechanism and therapy strategies of the osteolysis induced by polyethylene particles.