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Objective: The aim of this study was to evaluate the performance of dual-mobility (DM) cup systems for revision total hip arthroplasty (rTHA) in patients who had high risk for instability.
Methods: We prospectively followed up 34 hips of 30 patients (27 females, 3 males; mean age: 66.1 (range: 33 to 89) years) who underwent rTHA with DM cups for aseptic loosening in 23 hips, infection treatment as second or single stage in nine hips, and instability in two hips. Clinical functions of the patients were evaluated using the Harris Hip Score (HHS), and radiological migration or loosening of the DM cups were recorded. The survival of the components was calculated with the Kaplan-Meier survival analysis and failure was defined as any dislocation of the polyethylene (PE) insert, intraprosthetic dislocation (IPD), aseptic loosening of any component or total hip system revision due to any reason.
Results: The mean duration of follow-up was 3.52 (range: 2.05 to 6.26) years. There was one dislocation of PE insert (2.9%), which was treated with closed reduction. There were two (5.8%) re-revisions for cemented DM cup due to migration. There was one PE insert and head change due to subacute infection. The mean HHS increased from 42.8 ± 6.7 (range: 34 to 60) points preoperatively to 87.3 ± 5.8 (range: 75 to 98) points postoperatively. The cumulative survival rate of the DM cup system was 91.2% (95% CI: 81.6 e100%) with any revision, 94.1% (95% CI: 86.2e100%) with aseptic loosening and %97.1 (%95 CI: 91.4 e100%) with dislocation as the end point at 3.5 years.
Conclusion: Dual-mobility cups may provide good stability and represent a good option for revision acetabular reconstruction in patients who have high risk for instability.
Level of evidence: Level IV, therapeutic study.