Alternative Wear Couples 59
Polyethylene wear In Total Hip Arthroplasty -matched pair analysis of ceramic and metal heads
C. S. Ranawat, V. J. Rasquinha and J. A. Rodriguez
Purpose
The objective was to study the most important variable i.e. femoral head in the generation of polyethylene wear debris in THA.
Method
52 pairs of patients (minimum follow-up of 4 years) were matched for age, gender, body weight, surgeon, duration of follow-up and implant design and fixation. The only difference was the primary bearing surface, which was either ceramic or metal on polyethylene. The head diameter (28 mm) and head-neck taper was the same in both groups.
The wear measurements were determined by two independent observers utilizing computer-assisted wear analysis on digitized standardized radiographs described by Martell et ol (1997) due to the least reported observer variability. The radiographs were also evaluated for osteolysis or aseptic loosening.
Results
The mean linear wear rate in the ceramic group was 0.13mm/yr and in the metal group was 0.17mm/yr, which was significant (p<0.05). There was no case of osteolysis or aseptic loosening at a mean follow-up of 5.S years.
Clinical Relevance
The superior wear characteristics of ceramic on polyethylene hip articulations have the potential to markedly improve the longevity of contemporary THA.
