Cup-Cage Reconstruction for Pelvic Discontinuity: Encouraging Long-Term Survival.

Background: Pelvic discontinuity (PD) poses a difficult challenge in revision total hip arthroplasty (rTHA). There is a paucity of evidence assessing five- to ten-year outcomes of cup cages for PD. This study aimed to review the survivorship and outcomes of cup-cage constructs for PD.

Methods: Cases without PD or with < 2-year follow-up were excluded. There were 48 cup-cage revisions identified with a mean follow-up of 7.2 years (range, two to 20). The mean age was 77 years, and 71% were women. Kaplan-Meier analysis was used to determine survival with all-cause and aseptic loosening re-revision as endpoints. Secondary outcomes included radiological failures and patient-reported outcomes (PROMs).

Results: All-cause re-revision survival was 80% (95% CI [confidence interval] 0.70 to 0.93) at five years and 68% (95% CI 0.54 to 0.85) at 10 years. Re-revision survival for aseptic loosening of the cup-cage construct was 95% (95% CI 0.89 to 1.00) at five years and 85% (95% CI 0.74 to 0.98) at 10 years. There were 13 (27%) patients who underwent re-revision at a mean of 45 months post rTHA (range, one to 112). Aseptic loosening prompted re-revision in five of 48 (10%) cases at a mean of 68 months (range, 29 to 98). Of these, three required cup revisions for loosening, and two required isolated cage/liner revisions with well-fixed cups. There were three patients who had resection arthroplasty for chronic infection. There were three patients revised for instability with liner exchange or femoral revision only, as the cup-cage constructs had not failed. Patient-reported pain (mean Western Ontario and McMaster Universities Arthritis Index (WOMAC), 83.5) and function (mean WOMAC function 75.4, Oxford Hip Score (OHS), 71.2) were acceptable.

Conclusion: Cup-cage reconstruction is a good solution for PD with encouraging five- to ten-year results and acceptable survivorship and PROMs.