Metal-on-conventional polyethylene (MoPc) bearing wear-related biological reactions in total hip arthroplasty (THA) continue to raise concerns among young, active patients. Ceramic-on-ceramic (CoC) bearings may offer improved outcomes in this patient population.

The aim of this study was to determine if, more than 20years postoperatively, there is a difference between MoPc and CoC THA in terms of (1) survivorship, (2) related complications, (3) radiographic signs of wear, and (4) functional scores.

CoC bearing THAs have superior clinical results compared to MoPc THAs.

A total of 140 hips in 116 patients with a mean age of 42years were randomised to receive CoC or MoPc THA between 1996 and 2001. Sixty-nine hips in 58 patients received MoP and 71 hips in 68 patients received CoC. Revision rate, WOMAC score, and radiological signs of osteolysis and loosening were compared at last follow-up.

After a mean follow-up of 21years (19–23), 40 patients (48 THAs; 34%) had died and 6 patients (6 THAs; 4%) were lost to follow-up. Aseptic revision rate was significantly higher in the MoPc group (17/69; 24.6%) versus CoC (2/71; 2.8%; p<0.001). Kaplan–Meier survivorship estimator with revision for aseptic reasons was 73.6% (95% CI: 63.3–84.9%) for MoPc and 96.9% (95% CI: 92.8–100%) for CoC (p<0.001). On radiographic evaluation, 13% (3/23) MoPc were considered loose versus no CoC, and 61% (14/23) MoPc versus 6% (2/33) CoC showed osteolytic signs (p<0.001). CoC had better mean WOMAC scores than MoPc (11.0 vs. 19.4; p=0.048). No ceramic fracture was observed.

In this RCT, CoC bearings provided excellent results and were safer than MoPc bearings at more than 20-year follow-up. The long-term in vivo behaviour of CoC bearing makes it a great THA option for middle-aged patients and should be compared to newer polyethylene bearings.

I.