Stable syndesmosis after conservative and operative treatment of isolated grade II high ankle sprains with more than two years follow-up; a retrospective case-control study with bilateral external torque CT

Abstract Background Current literature lacks consensus on managing latent unstable isolated syndesmotic injuries. Stability is considered a prerequisite for a good clinical outcome. But so far, it is unknown how stable isolated syndesmotic lesions heal after conservative and surgical treatment. Purpose The purpose of this study was to retrospectively analyze patients with isolated Grade II syndesmotic lesions according to syndesmotic stability, structural changes and clinical outcome. And whether there is a difference between conservative and surgical treatment. Study Design Retrospective case-control study Methods A retrospective analysis of 20 patients (10 conservatively treated, 10 surgically treated) with isolated syndesmotic lesions was conducted, with a minimum 2-year follow-up. Evaluation included bilateral external torque CT for syndesmotic stability, MRI for ligament healing structural changes, and clinical examination with foot-specific patient-reported outcome measures (PROMs). Results Scarred syndesmosis demonstrated stability in external rotation, with non-significant changes compared to the healthy contralateral side: anterior distance (AD): 0.4 mm ±1.2 (p value 0.718), posterior distance (PD): -0.1 mm ±1.3 (p value 0.709), tibiofibular clear space (TCS): 0.3 mm ±0.8 (p value 0.321), external rotation (ER): 1.8 ° ±2.9 (p value 0.684). No statistically significant differences were observed between conservative and operative treatments regarding syndesmotic stability, structural changes, or clinical outcomes. Conclusion Conservative and operative treatments for isolated Grade II syndesmotic lesions achieved comparable results in syndesmotic stability and healing. Level of Evidence IV