AN INDIRECT COMPARISON OF 3RD-BODY WEAR IN RETRIEVED HYDROXYAPATITE-COATED, POROUS, AND CEMENTED FEMORAL COMPONENTS

The osteoconductive properties of hydroxyapatite (HA)-coated titanium implants are well documented, but eventual coating degradation may res ult in HA particles adjacent to the substrate, and if the particles we re to migrate into the joint space then accelerated polyethylene wear might be expected. As an indirect indication of third-body wear, the a uthors used laser interference microscopy to measure and compare surfa ce roughness on modular heads from 15 clinically retrieved HA-coated f emoral components, with heads from 15 retrieved uncemented (porous) an d 15 cemented implants. The results showed increased median surface ro ughness over initial manufacturer specifications in all groups, but th e cobalt-chrome heads from the HA-coated group showed significantly le ss surface roughness and less deep scratches than the heads from eithe r the porous or uncemented group. Three-body wear appears to be a comm on problem, but evidence available suggests that it is no more of a pr oblem with HA-coated devices than porous or cemented.