Using a patterned microtexture to reduce polyethylene wear in metal-on-polyethylene prosthetic bearing couples

1A. Borjali, 2J. Langhorn, 1K. Monson, and 1B. Raeymaekers

1Department of Mechanical Engineering, University of Utah, Salt Lake City, UT 84112, USA

2DePuy Synthes, Warsaw, IN 46582, USA

Abstract

It is well-documented that the service life of metal-on-polyethylene prosthetic hip implants, in which a CoCrMo femoral head articulates with a polyethylene acetabular liner, may be limited by polyethylene wear. Particles generated by polyethylene liner wear may cause an inflammatory response of the immune system, which can in turn lead to aseptic implant loosening. Many researchers have tried to reduce polyethylene wear by improving mechanical properties of the polyethylene acetabular liner and/or altering the design of the femoral head/acetabular liner pairs and manufacturing ultra-smooth articulating surfaces. In contrast, we show that manufacturing a patterned microtexture of concave “dimples” on the surface of a polished CoCrMo surface significantly reduces polyethylene wear. Gravimetrically measuring polyethylene wear during pin-on-disc experiments, we demonstrate that microtextured CoCrMo reduces counterface polyethylene wear by more than 50% when compared to polished CoCrMo surfaces. We evaluate wear for three different commercially available polyethylene materials used in prosthetic hip implants, articulating against several different microtexture designs. We also demonstrate contact reduction of the articulating bearing surfaces by correlating polyethylene wear with white-light-interferometry surface topography measurements.