RECONSTRUCTION OF MAJOR ACETABULAR BONE DEFECTS USING BONE BANK HEMIPELVI: A CONTINUOUS SERIES OF 20 CASES

Abstract

Purpose: We report our experience with acetabular reconstruction using cyropreserved bone bank hemipevli without a scaffold and total hip arthroplasty for major acetabular defects. Between 1985 and 1999, among 262 acetabular reconstructions requiring massive allografts using cryopre-served bone, 20 cases were performed with hemipelvi.

Material and methods: Mean age of the population was 56 years. The acetabulum had been operated on a mean three times. The 20 defects corresponded to Paprosky grade IIIB or SOFCOT grade IV bone loss. Clinical and radiological review of the 20 hips was made at a mean five years after treatment. None of the patients was lost to follow-up. The overall Postel Merle d’Aubigné (PMA) score at last follow-up was 17 for preoperatively scores at D2, M4 and S3 respectively. The acetabular defects were major and poorly described by the conventional systems. For example, the mean height of the bony defects was about 10 cm measured from the base of the radiographic U and the superolateral rim of the remaining roof.

Results: Globally, 13 patients had not required a reoperation at last follow-up. We had one postoperative death and two early displacements as well as two infections including one haematogenous infection. The Oakeschott criteria were used to analyse the review radiographs. Aseptic lysis of the graft was observed in five cases (generally around the 13th postoperative month) that required revision; a bone graft and a supporting ring were used in all cases because more bone stock was available than for the first revision. Among the 13 cases that did not require a new procedure, there were two with an ascended graft displacing the centre of rotation about 10 mm, followed by radiographic stability. The overall functional score for these 13 hemipelvi at last follow-up was 17 demonstrating the superior functional result compared with arthroplastic resection, the only alternative for such important loss of bone stock. It is not possible to implant a large non-cemented socket in these cases. Radiographic fusion was achieved, documented in 13 cases by the development of bony bridges or disappearance of the interface with oriented lines of force. Early graft resorption does not appear to occur when a metallic scaffold is associated (Garbuz).

Discussion: In all, 19 hips still had their total arthroplasty at last follow-up (one patient with failure preferred trocahntero-iliac coaptation.

Conclusion: Due to the inefficacy of alternative methods, this mode of restoration for major bone loss of the acetabular region (which facilitates secondary revision) appears to provide satisfactory results since the probability of preserving the prosthesis at a mean five years was slightly greater than 3/5. A stronger metallic scaffold may be the solution for the future.