The effect of diffusion hardened oxidized zirconium wear debris on cell viability and inflammation--an in vitro study

Wear debris generation in total joint replacement remains a concern because of its association with aseptic loosening, osteolysis, and ultimately implant failure. In a quest to develop new implant materials with reduced wear and improved biocompatibility a new composition of oxidized Zr2.5Nb alloy; diffusion hardened oxidized zirconium (DHOxZr) has been developed. In this study, we have determined the in vitro biocompatibility of the wear debris of this new composition and compared it to wear debris particles of Ti6Al4V, Cobalt, and CoCr. The cytotoxicity of these particles on fibroblast-like cells (L929) and osteoblast-like cells (SaOS2) was assessed using lactate dehydrogenase and DNA quantification assays. The inflammatory response to these particles was assessed by release of interleukin-1 beta and tumor necrosis factor from macrophage-like cells. The results showed that wear debris generated from DHOxZr was less cytotoxic and elicited a reduced inflammatory response as compared to that of Cobalt or CoCr and might therefore offer a benefit as a joint prosthesis.