FUNCTIONAL AND CLINICAL OUTCOME OF CEMENTLESS PRIMARY ARTHROPLASTY OF THE HIP USING LARGE DIAMETER CERAMIC BEARING COUPLES

Abstract

Aim: To report the clinical, functional and radiological outcome of consecutive primary hip arthroplasties using large diameter (36mm and above) ceramic bearing couples. We believe this to be one of the first reported series in the UK.

Methods: We prospectively reviewed 319 consecutive primary THA using fully HAC coated acetabular shell and fully HAC coated stem (JRI Ltd) in 302 patients, with minimum follow-up of 12 months. A Biolox-Delta ceramic liner with an 18 deg taper and Biolox-Delta ceramic head (36mm and 40mm) were used in all cases, which were performed in one institution by 3 surgeons. None were lost to follow-up. Clinical outcome was measured using Harris, Charnley Oxford, EuroQol EQ-5D scores. Radiographs were systematically analysed for implant position, loosening, migration, osteolysis. Return to sports and hobbies were recorded.

Results: Mean age was 64.9 yrs (11–82yrs). There were no dislocations. 50–62mm acetabular shells were used. 36 mm head was used in 96% of cases. No acetabular revisions were performed for aseptic loosening. Other re-operations were for infection (1), peri-prosthetic fractures (1). The mean Harris and Oxford scores were 95 (88–97) and 14.1 (12–33) respectively. The Charnley score was 5.7 (5–6) for pain, 5.8 (4–6) for movement and 5.9 (4–6) for mobility. There was a significant improvement in the range of movement of the hip. There was no migration of acetabular component. Acetabular radiolucencies were present around one shell. No acetabular liner wear was demonstrated in CT Scans. Mean inclination was 47.4deg(37–65). Mean EQ- 5D description scores and health thermometer scores were 0.84 (0.71–0.92) and 88 (66–96). With an end point of definite or probable loosening, the probability of survival was 100%. Overall survival with removal or repeat revision of either component for any reason as the end point was 99.1%.

Conclusion: The results of this study show an excellent clinical and functional outcome and support the use of a fully coated prosthesis with ceramic bearing couples. We envisage to monitor and prospectively report the long-term outcome of this series of patients.