Microtextured CoCrMo alloy for use in metal-on-polyethylene prosthetic joint bearings: multi-directional wear and corrosion measurements.

The longevity of metal-on-polyethylene (MoP) prosthetic hip joint bearings, in which a polished CoCrMo femoral head articulates with a polyethylene liner, may be limited by mechanical instability or inflammation resulting from osteolysis caused by polyethylene wear debris. This study uses laser surface texturing to manufacture a pattern of shallow spherical microtexture features on a polished CoCrMo surface. Gravimetric wear measurements of a highly-crosslinked polyethylene pin articulating with a CoCrMo disc under multi-directional shear demonstrate that polyethylene wear is reduced by more 50% when articulating with a microtextured as opposed to a polished CoCrMo disc. Electrochemical measurements also show that laser texturing does not negatively affect the corrosion potential of CoCrMo.

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

The longevity of metal-on-polyethylene prosthetic hip joint bearings, in which a CoCrMo femoral head articulates with a polyethylene liner, is often limited by polyethylene wear and osteolysis caused by polyethylene wear particles. Current approaches to reduce polyethylene wear include improving the mechanical properties of the polyethylene liner, and/or manufacturing ultra-smooth articulating surfaces. In contrast, this experimental work shows that adding a patterned microtexture of concave "dimples" to a polished CoCrMo surface significantly reduces polyethylene wear by promoting the formation of an elastohydrodynamic lubricant film, which reduces contact between the CoCrMo and polyethylene bearing surfaces. Using a gravimetric method to measure polyethylene pin wear during pin-on-disc experiments, it was demonstrated that microtextured CoCrMo caused reduced polyethylene wear compared to polished CoCrMo surfaces. Wear was quantified for different polyethylene materials currently used in commercial prosthetic hip joint bearings, and for several microtexture geometries. It was also documented by correlating polyethylene wear with surface topography measurements that the patterned microtexture reduced contact between the articulating bearing surfaces.