PROSPECTIVE RANDOMIZED TRIAL COMPARING ALUMINA CERAMIC-ON-CERAMIC WITH CERAMIC-ON-CONVENTIONAL POLYETHYLENE BEARINGS IN TOTAL HIP ARTHROPLASTY. UP TO 10 YEARS FOLLOW-UP IN PATIENTS UNDER AGE 60

Abstract

Total hip replacement in the young active patient remains one of the major challenges in orthopaedics today. The use of ultra high molecular weight (UHMW) polyethylene acetabular liners is known to cause polyethylene wear related osteolysis, the major limiting factor in its use in the younger active patient. Modern alumina ceramic articulations have been developed in order to reduce wear and avoid polyethylene debris. This prospective randomized long-term study aims to compare the outcome between an alumina ceramic-on-ceramic (CC) articulation with a ceramic on UHMW polyethylene articulation (CP). In the younger active patient, is one option superior to the other with regard to patient satisfaction, osteolysis and implant longevity?

56 hips in 55 patients with mean age 42.2 (range 19–56) each received uncemented components (Wright Medical) and a 28mm alumina head with acetabular liner selected via sealed envelope randomization following anesthetic induction. Subsequent regular clinical and radiologic follow up measured patient outcome scores and noted any radiological changes.

26 CP hips and 30 CC hips were evaluated. One failure required revision in each group. Mean St Michael’s outcome score for each group with up to 10 years follow-up (median 8 years, range 1–10) was 22.8 and 22.9 respectively (p=0.057). Radiographs with a minimum 5 years post-operative follow-up were analyzed in 42 hips (23 CC and 19 CP). Radiolucency of all 3 acetabular zones was identified in one of the CP hips. There was no evidence of osteolysis or loosening identified in the remaining hips. The mean time of wear measurement for the CC group was 8.3 years (SD 1.3, Range 4.8–10.1 years) and for the CP group was 8.1 years (SD 0.9, Range 6.1–9.2 years)(p=0.471). Wear was identified in all but one of the CP replacements but only 12 of 23 CC articulations. The mean wear for the CC group was 0.14 mm (SD 0.16, Range 0–0.48 mm) and for the CP group was 0.89 mm (SD 0.6, Range 0–2.43 mm)(p< 0.001). Extrapolating the annual wear rate from these figures, the respective wear is 0.02mm for the CC group compared to 0.11mm per year for the CP group.

To our knowledge this is the first long term randomized trial comparing in vivo ceramic-on-ceramic with ceramic-on-conventional polyethylene hip articulations. Other than significantly greater wear in the polyethylene group there was no significant difference in long-term outcome scores between the two groups with up to 10 years of follow-up. The use of a ceramic-on-ceramic bearing is a safe and durable option in the young patient avoiding the concerns of active metal ions and osteolytic polyethylene debris. These patients remain under review.