Introduction. Oxidized zirconium (OxZr) is used as a ceramic surface for femoral components in total knee arthroplasty (TKA). The aim of this study was to investigate its performance by examining retrieved femoral components and their corresponding PE inserts in matched comparison with conventional chrome/cobalt/molybdenum alloy (CrCoMo). Methods. 11 retrieved posterior stabilized (PS) TKA with an OxZr femoral component were included. From a cohort of 56 retrieved TKA with CrCoMo femoral components, pairs were matched according to duration of implantation, patient age, reason for revision, and BMI. The retrieved tibial polyethylene (PE) inserts were analyzed for wear using the Hood classification. Femoral components were optically viewed at 8–32x magnification and screened for scratching, pitting, delamination, and striation. Profilometry was performed to measure surface roughness of the OxZr components using a non-contact white light profiler. Results. The prostheses were in situ for a mean of 18.5±10.6 (OxZr) and 19.5±14.3 (CrCoMo) months (p=0.41). None of these cases were revised for problems directly related to the use of OxZr. There was one reaction to the implant in the CrCoMo group. The average wear of the tibial PE inserts was significantly lower with OxZr components (41.5±16.8 vs. 60.1±22.0, p=0.01). The average wear score in the visual analysis of the femoral components was significantly lower for the OxZr (1.6±1.3 vs. 9.5±0.6, p=0.005). Discussion and Conclusion. Femoral components made of OxZr are less sensitive to in vivo wear damage than those of CrCoMo. PE inlays show significantly less in vivo wear damage in combination with an OxZr femoral component

INTRODUCTION

One of the recent advances in the hard-on-hard hip arthroplasty is the development of a new material of diffusion hardened oxidised zirconium (DHOxZr). The DHOxZr material consists of a ceramic layer on the top surface which is supported by a thick oxygen diffusion hardened (DH) zone underneath. With the desired properties of metal substrate, ceramic surface and a gradient structure of the oxygen diffusion zone, the DHOxZr-on-DHOxZr bearing combination is expected to produce low wear and minimal metal ions. This can possibly address the concerns associated with metal hypersensitivity associated with metal on metal bearings and fracture risk associated with ceramics. The aim of this study was to evaluate the wear of DHOxZr-on-DHOxZr as a possible hard on hard bearing combination in hips.