Midterm Outcomes After Suture Button Fixation for Arthroscopically Confirmed Concomitant Syndesmotic Instability in Chronic Lateral Ankle Instability: A Retrospective Cohort Study.

Background: Distal tibiofibular syndesmosis instability (DTSI) often coexists with chronic lateral ankle instability and may delay recovery. Suture button fixation is widely used, but its benefit in this setting is uncertain. Purpose: To evaluate midterm outcomes of suture button fixation for DTSI with concomitant lateral ankle instability. Study Design: Cohort study; Level of evidence, 3. Methods: Patients who underwent surgery for lateral ankle instability with arthroscopic syndesmosis assessment between 2017 and 2023 were retrospectively identified. Patients with an intact syndesmosis formed the intact group, whereas those with arthroscopically confirmed dynamic syndesmotic instability (≥2-mm diastasis) underwent additional suture button fixation and formed the instability group. All patients received standardized lateral ligament surgery and rehabilitation. Clinical assessments were performed preoperatively, at 12 months, and at final follow-up using Karlsson-Peterson, Foot and Ankle Ability Measure (FAAM), Tegner, Ankle Ligament Reconstruction-Return to Sport after Injury (ALR-RSI), visual analog scale (VAS) pain scores, and ankle range of motion. Group differences were analyzed with α = .05 and interpreted using minimal clinically important differences (MCIDs). Results: Of 216 eligible patients, 154 completed follow-up at a mean of 67.3 ± 24.8 months (range, 24-113 months). No bilateral cases were included; therefore, the number of ankles was identical to the number of patients: 80 patients (80 ankles) in the intact syndesmosis group and 74 patients (74 ankles) in the syndesmotic instability group. Preoperatively, the instability group had lower Karlsson-Peterson scores than the intact group, with a median between-group difference of -4.00 points (95% CI, -6.00 to -2.00; Conclusion: Our study demonstrated that, for patients with chronic lateral ankle instability and arthroscopically confirmed concomitant DTSI, suture button fixation combined with lateral ligament surgery was associated with substantial midterm functional improvement, with outcomes approaching those of patients with an intact syndesmosis. However, because the comparison involved biologically distinct cohorts, these findings should be interpreted as supportive rather than definitive. Future matched or randomized studies are needed to clarify the independent contribution of suture button fixation.