Adjunctive posterior tibial tendon transfer during supramalleolar osteotomy for varus ankle osteoarthritis: a matched cohort study

The role of adjunctive posterior tibial tendon (PTT) transfer in supramalleolar osteotomy (SMO) for varus ankle osteoarthritis remains unclear. This study aimed to compare clinical and radiographic outcomes between SMO with adjunctive PTT transfer and isolated SMO, with particular focus on correction of talar tilt. We retrospectively reviewed patients with varus ankle osteoarthritis who underwent SMO between April 2018 and April 2025. Twenty-three patients treated with SMO and PTT transfer were matched 1:1 with 23 patients treated with isolated SMO according to preoperative talar tilt, Takakura–Tanaka stage, concomitant calcaneal osteotomy, age, and operative period. Radiographic parameters, clinical scores, satisfaction, and postoperative Takakura–Tanaka stage were compared. ANCOVA was used to compare postoperative talar tilt after adjustment for preoperative talar tilt and concomitant calcaneal osteotomy. Mean follow-up was 57.6 months in the SMO + PTT group and 65.6 months in the SMO group. Talar tilt decreased from 12.3° to 5.0° in the SMO + PTT group and from 12.6° to 8.3° in the SMO group. The SMO + PTT group had greater talar tilt correction than the SMO group (7.4° versus 4.3°; p = 0.042) and a more favorable postoperative Takakura–Tanaka stage distribution ( p = 0.014). After adjustment, adjunctive PTT transfer remained associated with lower postoperative talar tilt ( p = 0.018). No significant between-group differences were found in clinical improvement or satisfaction. PTT transfer during SMO was associated with greater correction of talar tilt and a more favorable postoperative Takakura–Tanaka stage distribution, without a detectable difference in short- to mid-term patient-reported or clinical outcomes.