Evaluating Tribological Properties of Materials for Total Joint Replacements Using Scanning Probe Microscopy

Scanning probe methods have been utilized to reveal useful information regarding the tribological phenomena of total joint replacement materials. In particular, studies on the effect of synovial fluid constituents on the tribological response of polymeric materials and the effect of residual stresses on the fretting response of metallic materials are described. The studies show that an adsorbed layer of proteins causes an increase in friction behavior of hydrophobic ultrahigh molecular weight polyethylene (UHMWPE) owing to denaturation upon adsorption. Changing the crystallinity of UHMWPE can affect the friction behavior and have ramifications for mechanisms of protein adsorption. Studies on fretting behavior of metallic (CoCrMo) implant materials showed that significant plastic deformation of the metal may not be a prerequisite for oxide fracture. In addition, results suggest that nearly neutral boundary lubricants may provide significant protection against the onset of fretting. Finally, the chapter concludes with an outlook on how scanning probe methods can be used to provide greater insight into the design of biomaterials.