Wear of total joint replacement (TJR) articulating surfaces is a major concern in the orthopaedic community and the improved wear performance of implantable materials is of great interest. The aims of this research were to explore 1) the creation and basic performance of an integrated TiC micro-textured surface on a Ti6Al4V ELI alloy for improved wear performance, and 2) the biocompatibility of the existing LIMB microtextured CoCrMo-carbide surface.

Preliminary investigation results were used to develop a refined microwave plasma chemical vapor deposition (MPCVD) processing parameter matrix. The microtextured surface created from a Ti6Al4V substrate by MPCVD processing was a TiC coating (confirmed by XPS). Each MPCVD processing parameter set resulted in an increase in the surface roughness. Surface Vickers microhardness values ranged from a 10% loss to a 208% gain when compared to polished, as-received Ti. The weight gain of specimens with an improved microhardness was distinctly lower than the weight gain of specimens with little or no improvement in microhardness. Images of cross-sectioned specimens were analyzed to determine that the visible surface layer thickness of the specimen with a 10% loss in HV was 2 times greater than any of the other 6 crosssectioned specimens. An increase in Vickers microhardness along the depth of the crosssection indicated an overall increase in HV of the bulk material. This study demonstrated that an integrated micro-textured TiC surface layer grown from a Ti6Al4V ELI bulk material has the potential to improve the wear surface of Ti alloy implants.

To investigate the biocompatibility of the existing LIMB micro-textured CoCrMo-carbide surface, osteoblast-like MG63 cells were propagated on 4 LIMB CoCrMo-carbide specimen types, polished as-received CoCrMo and control surfaces. The CoCrMo-carbide surface was not cytotoxic to MG63 cells. Cell viability and attachment to the CoCrMo-carbide surfaces was visually confirmed by field emission SEM. Type 1 collagen - as measured by ELISA from the media of cells grown on carbide test surfaces - was at least 40% less than type 1 collagen from polished CoCrMo or polystyrene test surfaces. The experiments in this study encourage further efforts to assess the biocompatibility of the carbide surface.