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Treatment of acetabular loosening and accompanying bone defects requires that the bone stock be rebuilt, the primary stability ensured, and the hip center of rotation restored to its anatomical location.
Acetabular reconstruction using morselized allograft and a reinforcement ring will meet these requirements and ensure medium-term survival.
Patients and methods
A retrospective study was performed on 95 acetabular revision cases (95 patients) performed between 1987 and 1995. The average age at revision was 69.5 years (42 to 86 years). Among these acetabular loosening cases, 12 cases had a type II Paprosky acetabular bone defect and 83 cases had a type III defect.
The average follow-up was 8 years (5 to 13 years). There were seven post-operative dislocations, three deep infections, and two cases of repeated acetabular loosening. The cumulative survival rate at 14 years was 77.9% (95% CI: 61.96% to 93.84%). The average Postel Merle d’Aubigné (PMA) score improved from 8 (range 6–11) preoperatively to 14.8 (range 8–18) at follow-up; the Harris score improved from 35.3 (range 11–52) to 71.1 (range 40–94) (P<0.001). Based on the parameters outlined by Ranawat, the optimal centre of rotation was restored in 45% of cases. Graft integration was found to be good in 60% of cases. The reinforcement ring had migrated in five cases, including two cases of acetabular loosening that required an additional revision. The functional result was better when the hip center of rotation was restored (P<0.05). Conversely, the position of the hip center of rotation had no effect on graft integration or acetabular fixation.
This series confirmed that acetabular reconstruction using morselized allograft and a reinforcement ring is effective in the medium term as a treatment for acetabular loosening with severe bone deficiency. It also revealed that restoring the hip center of rotation can improve functional results.
Level of evidence
Level IV, retrospective study.Le texte complet de cet article est disponible en PDF.
Keywords : Acetabular reconstruction, Morselized allograft, Acetabular reconstruction cages, Hip arthroplasty, Loosening, Hip center of rotation