LONG-TERM RESULTS OF 586 CEMENTLESS PRIMARY TOTAL HIP ARTHROPLASTIES USING FULLY HAC COATED ENDOPROSTHESIS

Abstract

Aim: To report the clinical and radiological outcome of consecutive primary hip arthroplasties using the JRI-Furlong Hydroxyapatite ceramic (HAC) coated femoral and acetabular components

Methods: We reviewed 586 consecutive cementless primary THA using HAC coated components in 542 patients, with a minimum 12-year follow-up to 18 years, performed at one institution between 1986 and 1994. Twenty eight (32 THA) were lost prior to 12-year follow-up, leaving 514 patients (554 THA) available for study. Threaded cups were used in 64% and press-fit cups with screws in the rest. Fully HAC coated stems were used in all patients. The clinical outcome was measured using Harris, Charnley and Oxford hip scores. Anterior thigh pain was quantified on a visual analogue scale (VAS) and quality of life using EuroQol EQ-5D. Radiographs were systematically analysed for implant position, loosening, migration, osteolysis and stress shielding. Polythene wear was digitally measured. The radiographic stability of the femoral component was determined by Enghs criteria

Results: The mean age was 75.2 yrs. Dislocation occurred in 12 patients (3 recurrent). Re operations were performed in 11 patients (1.9%). Four acetabular and one stem revisions were performed for aseptic loosening. Other re-operations were for infection (2), periprosthetic fractures (2), cup malposition (1), revision of worn liner (2). The mean Harris and Oxford scores were 89 (79–96) and 18.4 (12–32) respectively. The Charnley score was 5.7 (5–6) for pain, 5.3 (4–6) for movement and 5.4 (4–6) for mobility. Migration of acetabular component was seen in 4 hips. Acetabular radiolucencies were present in 54 hips (9.7%). The mean linear polythene wear was 0.06mm/year. Stable stem by bony ingrowth was identified in all hips excluding one femoral revision case. Mean stem subsidence was 2.2mm (0.30–3.4mm). Radiolucencies were present around 37 (6.6%) stems. Mean EQ- 5D description scores and health thermometer scores were 0.81 (0.71–0.89) and 86 (64–95). With an end point of definite or probable loosening, the probability of survival at 12 years was 96.1% for acetabular and 98.3% for femoral components. Overall survival at 12 years with removal or repeat revision of either component for any reason as the end point was 97.2%.

Conclusion: The results of this study support the continued use of a fully coated prosthesis and documents the durability of the HAC coated components. In our clinical experience, the Furlong prosthesis revealed encouraging radiographic stability over a long term period.