The influence of concave dimples on the metallic counterface on the wear of ultra-high molecular weight polyethylene

The aims of this study were to investigate how the dimples on a metallic counterface affect the wear rate of ultra-high molecular weight polyethylene (UHMWPE) in a multi-directional reciprocating pin-on-plate machine. The plates were high nitrogen stainless steel, representing the femoral head material. The pins used in this study were of ultra-high molecular weight polyethylene GUR 1120, which represents the material used in an acetabular cup. Three different cases were investigated: a smooth surface without dimples as a reference case, a surface with medium dimples with an average valley of 2.3 µm and a surface with large dimples with an average valley of 5.9 µm. It was found that all the dimples investigated did not improve the lubrication, but instead increased the surface roughness; consequently, the wear of UHWMPE was slightly increased.