International Orthopaedics - 2026-08-21 - Journal Article
Trabecular metal cups versus reconstruction cages for primary total hip arthroplasty in the irradiated acetabulum: a nine year comparative cohort study.
Lin YC, Lee SH, Peng SH, Hu CC, Chen WC, Lau NC
Topics
Key Takeaway
Trabecular metal cups achieved 100% 10-year survivorship free from aseptic loosening versus 88.2% for reconstruction cages in irradiated acetabula, with all-cause revision-free survivorship significantly favoring TM cups (100% vs 78.5%, p=0.040).
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Summary
This single-center retrospective cohort compared TM cups versus reconstruction cages for primary THA in 40 patients with prior pelvic radiotherapy, using Kaplan-Meier survivorship and Firth penalized Cox regression to address small-sample event rates. Ten-year aseptic loosening-free survivorship was 100% vs 88.2% (p=0.182), and all-cause revision-free survivorship was 100% vs 78.5% (p=0.040, HR 5.18), with four cage hips revised. Postoperative Harris Hip Score was significantly higher in the TM group (88.9 vs 81.8, p<0.001), though the difference did not reach the MCID.
Key Limitation
The study is critically underpowered (n=40, only four revision events) with wide confidence intervals (HR 5.18, 95% CI 0.82–32.74), rendering most between-group comparisons statistically inconclusive despite clinically meaningful numerical differences.
Original Abstract
PURPOSE
Acetabular reconstruction for primary total hip arthroplasty (THA) after pelvic radiotherapy is difficult because irradiated bone integrates poorly, and the optimal fixation method remains undefined, with comparative data lacking. We compared trabecular metal (TM) cups with reconstruction cages for implant survivorship and function.
METHODS
We retrospectively reviewed all 40 patients (40 hips) who underwent primary THA after pelvic radiotherapy at a single centre during 2008-2019 (20 TM cups, 20 reconstruction cages) in this unmatched cohort. Groups were compared with unpaired tests; survivorship was estimated by Kaplan-Meier (log-rank), with Firth penalized Cox regression and sensitivity analyses. The primary outcome was survivorship free from aseptic loosening; secondary outcomes were all-cause revision, complications and the Harris Hip Score (HHS).
RESULTS
The groups were similar in age, sex and radiation dose; follow-up was longer in the cage group (median 9.7 versus 8.4 years; p = 0.036). Ten-year survivorship free from aseptic loosening was 100% (TM) versus 88.2% (cage) (95% CI 59.9%-97.0%; p = 0.182; Firth hazard ratio 3.42, 95% CI 0.52-22.45); all-cause revision-free survivorship was 100% versus 78.5% (95% CI 51.8%-91.4%; p = 0.040; hazard ratio 5.18, 95% CI 0.82-32.74); four of 20 cage hips were revised. Postoperative HHS was higher for TM cups (88.9 versus 81.8, p < 0.001), below the minimal clinically important difference. Complications occurred in 10% versus 25% (p = 0.407).
CONCLUSION
In this small, retrospective cohort, TM cups showed numerically higher survivorship and function than reconstruction cages, but only the revision comparison was significant; the study is underpowered elsewhere. These hypothesis-generating findings require confirmation in larger, multicentre cohorts.