10 YEAR MULTI-CENTRE EVALUATION OF THE CORMET HIP RESURFACING ARTHROPLASTY.

Introduction: Hip resurfacing has become re-established in recent years as a viable option in younger, active individuals. The results of a multi-centre evaluation of the Cormet resurfacing device are presented. Methods: Data has been entered from 1997 onwards from 5 centres, patients being selected as suitable by 8 individual surgeons. Pre and intraoperative details recorded including indications, patient details, implant used, Harris Hip Score (HHS) and surgical approach. Results: A total of 905 procedures in 782 patients have been recorded (52% posterior approach, 39% anterolateral 9% Ganz approach). The mean follow-up is 2.8 years (0.1–9.5 yrs) and the mean postoperative HHS is 86.1 (range 25–100). The mean age at surgery was 54.4 years. 61% of patients were male. The principal diagnosis was; OA 88.3%, RA 4.3%, AVN 2.1%, posttraumatic OA 1.1%, DDH 2.1%, Perthes 0.7% and the remainder 1.4%. It is thought likely that many cases of OA had many of the above-named pathologies as a precursor. The mean maximum flexion postoperatively was 98.7 degrees. Uncemented heads (a recent innovation) were used in 10%. Kaplan-Meier survivorship is 93% at 9 to 10 years. Survivorship in the OA subgroup was 96.7% with approximately equal numbers for femoral head collapse, dislocation and cup loosening, but the vast majority due to femoral neck fracture, which in turn was generally associated with the posterior approach. Discussion: The results of this cohort (including all contributors’ learning curves) indicate highly satisfactory outcomes in terms of HHS and implant longevity. Subclassification of cases into those presenting abnormal anatomy and those with ‘ordinary’ OA indicates better survivorship still in the latter group. The surgical challenge varies more with hip resurfacing than with standard hip arthroplasty and this should be considered when results of surgery are reviewed. The revision options are generally much simpler than after standard THR.