ACETABULAR RECONSTRUCTION USING BONY ALLO GRAFT DURING REVISION OF TOTAL HIP PROSTHESES

Purpose of the study Aseptic loosening of the acetabular component is the most worrying problem after hip arthroplasty. During revision surg ery we prefer to rebuild a solid bony acetabulum close to the anatomy in which the implant will be cemented. On the basis of the first 48 ac etabular reconstructions using deep-frozen bony allografts, we carried out a review of our results in a pathology which will surely increase in the future. Material 48 hips were operated according to this techn ique. It has been possible to review 38 of them, with an average follo w-up of 7,3 years (extremes 5 years, and 9,6 years). The average age o f the population at the time of surgery was 63 years. Two etiologies p redominated: congenital hip dislocation sequelae and primitive hip art hritis. In 10 cases of massive deterioration, a Muller's ring was used to stabilize the allograft. Methods The results were analyzed at 6 mo nths, 2 years, 4 years, and at maximum follow-up, clinically, accordin g to Merle d'Aubigne grading system. Radiologically, Ranawat's criteri a were used to assess the re-centering of the reconstructed hips. The development of radiolucent lines and implants migration were also asse ssed. Results Clinically, the patients' comfort was always improved by pain relief. Radiologically, average acetabular upward migration of 5 mm and medialisation of 3.5 mm were observed. 24 hips presented radio lucent lines. 19 radiolucent lines were below 2 mm. 5 were greater tha n 2 mm and leaded to loosening. In 4 of these 5 cases of radiolucent l ines, there were acetabular migrations with failure. The radiological image remained stable afterwards. In these cases there was a real loos ening, necessitating further surgery. In all cases, partial resorption of the graft was observed. Discussion Study of our first 38 cases sho ws that bony allograft and cemented acetabulum, sometimes including an armature, is one possible solution to the problem of difficult acetab ular reconstructions. However, with an average follow-up of 7,3 years, we already have 5 (13 per cent) aseptic acetabular loosening, of whic h one has been operated on. Radiological analysis of these does not qu estion the allograft, but rather imperfect re-centering. Analysis of t he good results, 33 (87 per cent) stable acetabulum indicates re-fixin g in quasi-anatomical position, in conditions close to those of a firs t time arthroplasty, with the aid of perfectly stabilized bony transpl ants, and where contact with the receiver acetabulum is maximal. Concl usion Our follow-up is one of the longest in literature. But with a mi gration rate already of 13 per cent, it is not yet sufficient for us t o be permanently assured about the future of our patients, even if the ir age is greater and their activity less than those of patients havin g a first hip arthroplasty.