COMPARISON OF THREE BEARING SURFACES IN TOTAL HIP ARTHROPLASTY: A TEN YEAR FOLLOW-UP

BACKGROUND Despite many years of clinical experience the optimal bearing choice in total hip arthroplasty (THA) remains controversial. This study aims to directly compare the three widely used bearing surfaces: metal-on-highly crosslinked polyethylene (MoHXLPE), ceramic-on-ceramic (CoC) and metal-on-metal (MoM), regarding clinical and radiologic outcome parameters. METHODS From November 1999 to November 2001, 300 primary THAs were performed using the uncemented Alloclassic Variall cup and stem (Zimmer Inc., Warsaw, Indiana). The patients were divided into three groups according to the bearing couple implanted, with 100 persons in each group (MoHXLPE, CoC, MoM). Radiographic and clinical data was collected preoperative and at the last follow-up. RESULTS There were 71 patients (74hips) in the MoHXLPE group, 63 patients (67hips) in the CoC group and 67 patients (69hips) in the MoM group available at the time of the last follow-up. Average follow-up was 10.4 years (MoHXLPE: 10.4, CoC: 10.5, MoM: 10.3). In the MoHXLPE and the CoC group 3 hips each had to undergo revision surgery. In the MoM group 4 hips were revised. Overall survival with revision for any reason as the end point was 95.9% for MoHXLPE, 95.5% for CoC and 94.2% for MoM. The mean Harris Hip Score (HHS) for patients who were not revised was 92.5 points, 92.3 points and 94.3 points at the last follow-up, for the MoHXLPE, CoC and MoM group respectively. Radiolucent lines around the stem in Gruen zones one and/or seven occurred in 17% to 27% of THAs in the three groups without clinical relevance. CONCLUSIONS This study shows excellent results of all three bearing couples after ten years of follow-up. Our findings support the choice of ceramic-on-ceramic or metal-on-highly crosslinked polyethylene over metal-on-metal as bearing couple in active patients receiving a total hip replacement. Contrary to other studies we could not find advantages of CoC over MoHXLPE at mid-term follow-up.