Occult syndesmotic injury in chronic lateral ankle instability treated with Broström repair and suture-button stabilization

BACKGROUND Chronic lateral ankle instability may coexist with occult syndesmotic injury despite the absence of definite distal tibiofibular diastasis on static imaging. Because symptoms may overlap with those of isolated lateral ankle instability, this condition can remain unrecognized. This study hypothesized that selected patients with persistent anterior syndesmotic symptoms and stress-confirmed occult syndesmotic instability would demonstrate sustained improvement after combined Broström repair and suture-button stabilization. AIM To evaluate 5-year clinical outcomes of combined Broström repair and suture-button stabilization in this selected cohort. METHODS This uncontrolled retrospective case series at a tertiary hospital included 16 of 1487 patients treated from April 2018 to May 2021. Eligibility required chronic lateral ankle instability, focal syndesmotic symptoms, no static diastasis, failed conservative treatment, and qualitative confirmation by three intraoperative stress tests. No comparator or quantitative diagnostic threshold was used. All underwent combined Broström repair and suture-button stabilization. Repeated outcomes were analyzed using Friedman and Bonferroni-adjusted exact Wilcoxon tests. RESULTS The median injury-to-surgery interval was 21.0 months (interquartile range, 8.25-120.0 months). Preoperative visual analogue scale, American Orthopaedic Foot and Ankle Society, Foot and Ankle Ability Measure, and Karlsson scores were 3.00 ± 1.32, 69.69 ± 12.11, 69.67 ± 12.15, and 64.00 ± 11.86, respectively. At 5 years, scores were 0.44 ± 0.63, 92.06 ± 6.89, 89.21 ± 10.19, and 88.12 ± 8.69 (all adjusted P < 0.001; paired Cohen’s d z, -2.03, 2.06, 1.94, and 2.40). All patients returned to work at 2.44 ± 0.68 months. Seven patients (43.8%) underwent button removal at 1 year; none had implant-related symptoms at 5 years. CONCLUSION In this uncontrolled case series, combined treatment was associated with improvement, but the findings are exploratory and do not establish the independent benefit of suture-button stabilization.