Abstract
Purpose: We have used monoblock cryopreserved femoral heads for acetabular reconstruction without supporting material since 1985 for cemented total hip arthroplasty in patients with major acetabular defects. From 1985 to 1995, 140 reconstructions were performed. We present a prospective analysis of the clinical and radiological outcome at 10 years follow-up.
Material and methods: Mean age of the population was 61 years. Most of the patients had had two prior interventions. According to the SOFCOT classification, the 140 defects were: grade II 50%, grade III 35% and grade IV 15%.
The cryopreserved graft (femoral head bone bank) was used to reconstruct the acetabular defect. The graft was adapted to the size of the defect to fashion a congruent construct aimed at achieving primary stability. We did not use any supporting material in addition the primary osteosynthesis with one or two screws. A poly-ethylene cup was cemented in the graft. Most of the cement was applied onto the graft which was reamed to the size of the acetabulum. We retained a theoretical 6-year follow-up for review. All patients were seen for follow-up assessment using the Postel-Merle-d’Aubigné (PMA) clinical score and standard x-rays analysed according to the Oakeshott method. Kaplan-Meier survival curves were plotted taking change in status, revision for clinical failure as the endpoint.
Results: Mean overall follow-up was 8.5 years; it was 10 years for patients with an implant still in situ. Eight patients (5.7%) lost to follow-up were included in the series retained for analysis at mean 5-year follow-up. Thirty-five patients died during the follow-up period (25%). These patients had been followed for a mean four years before their death. Radiologically, cup tilt was not significantly altered over time. Conversely, the centre of the cup, measured from the U line, was not modified in the patients who died or in the group of living patients without revision at last follow-up. It was modified in the group of failure group: mean 28 mm postoperatively in the failure group reaching 39 mm at time of failure (ANOVA < 10-3). We had 26 failures (18%) which occurred at six years (mean); there was a peak at two years and another at nine years. Mean Kaplan-Meier survival was 13.5 years (95CI 12.5–14). The PMA clinical score improved from 3/5/3 (11) pre-operatively to 5.3/5.6/4.3 (15.2) at last follow-up.
Discussion: The overall results at 10 years in this series were globally satisfactory with a success rate above 70%. Failures were related to radiologically demonstrated graft compression with ascension of the centre of the cup measured from the U line. Comparing these results with data in the literature shows an improvement over the Harris series (7-year follow-up in a small group of 48 patients).
Conclusion: This method of acetabular reconstruction reserved for major bony defects has provided a 73% rate of success at ten years.
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.
