Abstract
Despite a large body of literature the optimal choice of bearing surface for total hip arthoplasty (THA) remains controversial. To avoid the brittleness and squeaking noted with ceramic-on-ceramic and the metal ion release associated with metal-on-metal (MOM) articulations, a novel hybrid coupling of ceramic-on-metal (COM) has been introduced. The purpose of this study was to compare changes in serum metal ion levels and the functional performance of COM and MOM bearing combinations.
Eighty-six patients (86 hips) undergoing THA between April 2009 and October 2010 were randomized to COM or MOM bearing couplings. All received identical uncemented acetabular shells and femoral components from two experienced surgeons using the same operative technique.
Demographic and peri-operative data were recorded. Serum cobalt and chromium levels, renal function and disease specific outcome scores (Oxford Hip, Harris Hip, UCLA activity) were assessed at baseline, 6 and 12 months post-operatively. Patients and outcome assessors remained blinded.
Mean age of the total cohort was 62.5 years. Randomization successfully matched groups for age, Body Mass Index, baseline serum Cobalt and Chromium levels, and pre-operative functional performance scores. One-year data is currently available for 25 of 44 COM and 26 of 42 MOM patients. No significant difference in serum cobalt (P value = 0.81) and chromium (P value = 0.66) levels between groups was noted. Improvements in outcome scores (Oxford Hip, Harris Hip, UCLA activity) were equivalent (P values 0.16 – 0.46).
At 1-year, COM and MOM hip arthroplasty articulations appear equivalent in terms of function and serum metal ion levels. Data collection out to 5-years post-surgery continues.
