Abstract
Introduction
Wear and osteolysis are major contributors which limit the durability of total hip arthroplasty (THA) and ultimately cause it to fail. Efforts were made to decrease the wear by highly cross-linked polyethylene (HXLPE) and using ceramic bearings. The purpose of this study is to analyze the five year performance of large sized (32mm and 36mm) ceramic and metal heads on X3 HXLPE (Stryker, Mahwah, NJ).
Materials and Method
From Jan 2006 to June 2008, 81 consecutive patients with minimum 5 year radiographic and clinical followup were identified from out institutional prospective database. 51 non-cemented THA (45 patients) had ceramic on HXLPE (CoX3) group and 30 hips (29 patients) had metal on HXLPE (MoX3) group. Mean age was 36 ± 8 years (36–76) and 50 ± 9 years (51–86) in ceramic and metal group, respectively. Wear rates were measured on an anteroposterior weight-bearing pelvis radiographs using the computer-assisted Roman software.
Results
The mean WOMAC, PAQ, HSS and UCLA scores for CoX3 and MoX3 groups at final follow-up were 13.2 ± 17.3, 10.1 ± 14.4, 36.4 ± 5.3 and 5.9 ± 1.8 and 16.5 ± 17.8, 17.1 ± 17.2, 31.6 ± 10.5 and 5.3 ± 1.6, respectively. At the final follow up, the mean wear rates were 0.022 ± 0.06 mm/yr and 0.022 ± 0.05 mm/yr for CoX3 and MoX3 groups, respectively. This was not statistically significant (p=0.8). When negative values were considered zero, wear rates for CoX3 and MoX3 groups were 0.037 ± 0.04 mm/yr and 0.033 ± 0.04 mm/yr, respectively (p=0.6). Radiographic analysis does not reveal any incidence of osteolysis or loosening in both groups.
Discussion and Conclusion
The five year wear rate of large diameter metal and ceramic femoral heads on HXLPE bearing demonstrated excellent similar wear rates. Longer follow-ups are required to assess superiority of one bearing over another.
