Indications, Causes, and Patient Risk Factors for Revision After Total Ankle Arthroplasty: A Descriptive Cross-Registry Analysis of the NJR, AOANJRR, and SwedAnkle Registries

Background/Objectives: Total ankle arthroplasty (TAA) is increasingly used to treat end-stage ankle arthritis, but comprehensive cross-registry data on revision patterns remain limited. This study describes indications, causes, and patient risk factors for revisions using three national registries. Methods: Aggregate data were extracted from the UK National Joint Registry (NJR; 22nd Annual Report 2025; n = 11,321), the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR; 2025 Ankle Supplementary Report; n = 5379), and the Swedish Ankle Registry (SwedAnkle; Annual Report 2024; n = 1852; survival estimates from a published sub-cohort, n = 1226). Metrics were compared descriptively without inferential pooling. Results: Across registries, 18,552 primary TAAs were identified. Ten-year cumulative per cent revision (CPR) was 9.54% (95% confidence interval [CI], 8.75–10.39) in the NJR, 13.5% (95% CI, 12.1–15.1) in the AOANJRR osteoarthritis sub-cohort, and approximately 26% (author-derived from Kaplan–Meier curves; see Methods) in SwedAnkle (1993 onwards implants). Aseptic loosening was the predominant cause of revision in all three registries; the rank of subsequent causes differed between registries (infection was second in the NJR and AOANJRR; in SwedAnkle, infection ranked below insert wear/breakage at 11.5%). AOANJRR Cox analysis identified younger age (hazard ratios (HRs), 2.00 for <55 vs. ≥75 years; 95% CI, 1.30–3.07; p = 0.001), earlier surgical era (HR, 1.91 for pre-2015 vs. 2015–2024; 95% CI, 1.53–2.38; p < 0.001), and obesity (HR, 1.52 for body mass index (BMI) ≥ 30; 95% CI, 1.06–2.19; p = 0.023) as significant independent predictors in AOANJRR Cox proportional hazards models (osteoarthritis sub-cohort for age, sex, BMI and ASA; all-diagnoses primary cohort for surgical era). Sex and American Society of Anesthesiologists (ASA) scores were not significant. Conclusions: Aseptic loosening was the predominant cause of revision in all three registries. The rank of subsequent causes differed: in the NJR and AOANJRR, infection was the second most frequent cause; in SwedAnkle, infection ranked below insert wear/breakage. Younger age, obesity, and earlier surgical era were independent predictors of revision in AOANJRR Cox proportional hazards models. The post-2015 era was associated with approximately 48% lower revision hazard; this association cannot be interpreted causally, as the independent contributions of implant design, surgical technique, patient selection, and other secular changes cannot be isolated from registry data. These findings may inform preoperative counselling, implant selection, and registry harmonisation efforts.