Influence of surface profile of Co-28Cr-6Mo alloy on wear behaviour of ultra-high molecular weight polyethylene used in artificial joint

Abstract

The influence of the surface profile of Co-28Cr-6Mo alloy (ASRM F75) on the wear behaviour of ultra-high molecular weight polyethylene (GUR1050) was investigated using pin-on-disc wear testing. The surface profile of Co-Cr-Mo alloy was designed to control not only the volume of wear of polyethylene but also the morphological features of the wear debris. The surface profile of Co-Cr-Mo alloy showed a surface roughness from the micrometre to nanometre scale, and a waviness curve with convex and concave parts of millimetres in size. The surface processing was conducted using micro slurry-jet erosion. The processed surface of Co-Cr-Mo alloy recorded the lowest wear rate of polyethylene in comparison with a conventional mirror finish surface. The equivalent circle diameter of the polyethylene wear particles from the processed surface was more than two-times larger than that using a conventional mirror finish surface. It was revealed that the larger debris group produced by the processed surface was able to reduce the secretion of IL-6 from macrophage activation during biochemistry tests. The results illustrate the possibility of controlling the major factors in the long-term osteolysis and loosening of artificial joints through the use of a surface modification of a Co-Cr-Mo alloy surface.