Total ankle arthroplasty via lateral transfibular approach with and without concomitant subtalar arthrodesis

Aims Concomitant subtalar pathology may require arthrodesis at the time of total ankle arthoplasty (TAA), yet direct comparisons of isolated TAA versus TAA + subtalar joint arthrodesis (STJA) via a lateral transfibular approach, using the same implant, remain limited. We compared ≥ five-year radiological, functional, and range of motion (ROM) outcomes. Methods This retrospective single-centre cohort included 119 patients from January 2015 to December 2020 with ≥ five-year follow-up: 50 underwent TAA with concomitant subtalar arthrodesis and 69 underwent isolated TAA. Outcomes were Foot and Ankle Outcome Score (FAOS), visual analogue pain scale (VAS), 12-Item Short-Form Health Survey questionnaire physical component/mental component summary (SF-12 PCS/MCS), ankle ROM, radiological alignment (lateral distal tibial angle, α, tibiotalar surface (TTS), and Saltzman alignment), and complications. Analyses were performed using Welch’s t -test or the Mann-Whitney U test for continuous variables and the chi-squared test or Fisher’s exact test for categorical variables, together with multivariable regression, using a two-sided significance level of α = 0.05 with Holm correction across angles. Post hoc minimum detectable effect (MDE) analysis at 80% power used observed SDs and group sizes. Results Ankle osteoarthritis (OA) + STJ OA had worse baseline FAOS (24.8 (7.0) vs 42.6 (8.8); p < 0.001), higher VAS (8.4 vs 7.2; p < 0.001), and lower ROM; there was no difference in SF-12 scores. At five years, both cohorts improved; between-group differences in PROMs and ROM were not significant. Radiologically, α and Saltzman alignment were similar; TTS differed modestly (−0.83° (95% CI −1.44 to −0.22); p = 0.048). Subtalar arthrodesis showed radiological bridging in 96% of patients (n = 48). Adjusted models showed no independent STJ effect and no smoking effect. MDE at 80% power was ~4.5 FAOS points (d = 0.52); the observed −3.4-point difference was below the threshold. Conclusion TAA + STJ achieved comparable five-year functional, pain, and radiological outcomes to isolated TAA via the transfibular approach, supporting the safety of this combined approach in selected patients. Cite this article: Bone Joint J 2026;108-B(9):1154–1161.