Radiographic Progression of Medial Ankle Osteoarthritis: The Influence of Global Coronal Alignment in a 7-Year Longitudinal Cohort.

Abstract

Background: The structural progression of medial ankle osteoarthritis (OA) and the contribution of global coronal limb alignment beyond local ankle deformity remain incompletely understood. Previous longitudinal studies have focused on local talar tilt with limited evaluation of global lower-limb alignment. We hypothesized that talar tilt, medial talar translation, and varus hip-knee-ankle angle (HKA) would be associated with radiographic progression in intermediate-stage medial ankle OA.

Methods: In this retrospective cohort study, 100 patients with Takakura stage 2 or 3A medial ankle OA managed nonoperatively were followed for a minimum of 5 years (mean, 83.3 ± 24.6 months). Baseline weight-bearing ankle radiographs and full-length standing teleradiographs were analyzed for talar tilt angle (TTA), medial talar translation (TCM), HKA, and additional parameters. Radiographic progression was defined as an increase in Takakura stage at final follow-up. Multivariable logistic regression was used to identify factors associated with progression. Multivariable linear regression evaluated factors associated with change in medial talar translation (ΔTCM).

Results: Radiographic progression occurred in 53 patients (53%). At baseline, patients with progression had greater TTA (4.4° ± 3.3° vs. 2.9° ± 2.3°, p = 0.007) and varus HKA (5.3° ± 3.3° vs. 3.0° ± 3.0°, p < 0.001) than nonprogression patients. In multivariable analysis, higher TTA (OR 1.73; 95% CI 1.25-2.38; p < 0.001), TCM (OR 1.70; 95% CI 1.23-2.34; p = 0.001), and HKA (OR 1.59; 95% CI 1.24-2.03; p < 0.001) were associated with progression. Baseline TTA and HKA were also associated with greater ΔTCM over time. The model demonstrated strong discrimination (area under the curve = 0.88).

Conclusions: Baseline talar tilt, medial talar translation, and global varus limb alignment were associated with radiographic progression of intermediate-stage medial ankle OA. These findings suggest that structural deterioration may reflect the combined influence of intra-articular deformity and global alignment rather than an exclusively local process.

Level of evidence: Level III (Prognostic). See Instructions for Authors for a complete description of levels of evidence.