Abstract
Purpose: We report a retrospective continuous series of 107 total hip arthroplasties using a hydroxyapatite-coaated cup followed for a mean 9.67 years. We studied implant stability and component wear.
Material and methods: One hundred total hip arthroplasties were performed between January 1991 and January 1992. The series included 67 women and 40 men operated by the same surgeon who used the same Alizé cup and Aura cementless stem. Mean age at surgery was 66.5 years (range 30–85). Mean follow-up at review was 9.6 years. We retained 63 hips for analysis excluding 17 deaths, 16 patients lost to follow-up, 10 patients who could not be followed correctly, and only one implant ablation (0.9%). The implant was a first intention prosthesis in 90.7% of the cases and a second operation to replace a loosened primary prosthesis.
The Postel Merle d’Aubigné score was used to assess clinical outcome and all patients responded to a self administered questionnaire. Radiographically, we searched for signs of instability (tilt, displacement) and implant wear using precise digitalized measurements on successive digitalized x-rays with MetrOs software. We searched for qualitative radiological signs of bone reaction in contact with the implant.
Results: The overall PMA score improved from 10.63 preoperatively to 16.98 at the intermediary 5-year follow-up and was 15.77 at the 10-year follow-up. Satisfactory results were obtained in 93.9% of the patients at five years and 98.5% of the patients (64 hips) at 10 years. There were two fractures of the ceramic head after direct fall on the greater trochanter (requiring changing the femoral implant, the head and the polyethylene insert). There was one cup loosening at 9.5 years with verticalisation of the implant in an active athlete. Analysis of the x-rays did not demonstrate any abnormal condensation or lucent lines. Bony defects were observed in one case. The MetrOs radiographic data were available for 55 hips. At five years, mean wear was 0.53 mm, which increased to 0.76 mm at ten years (range 0.16 – 2.24 mm). Cup ascension was 0.15 mm at five years and 0.76 mm at 10 years. Mean cup tilt was 46.2° immediately after implantation and varied a mean 0.7° at five years and 1° at ten years.
Discussion and conclusion: This radioclinical study at ten years follow-up demonstrates that the hydroxyapa-tite surfaced Alizé implant is stable over time. The clinical results in this study were satisfactory with minimal regression of the PMA score related to patient ageing. The x-rays analysed with a rigorous and precise measurement instrument provided reassuring results. We discussed the one cup loosening and the clinical course of the two patients who underwent revision procedures after trauma-induced fracture of the ceramic head.
The abstracts were prepared by Docteur Jean Barthas. Correspondence should be addressed to him at Secrétariat de la Société S.O.F.C.O.T., 56 rue Boissonade, 75014 Paris.
