Unlocking the surgical threshold: WBCT as a predictor in unstable ankle syndesmosis injuries

Background Objective data are crucial for diagnosing syndesmotic instability. Currently, the gold standard is arthroscopy, which carries inherent risks. Therefore, specific criteria are necessary to recommend surgical intervention safely. Comparative Weight-bearing computed tomography (WBCT) serves as a valuable tool for assessing syndesmotic symmetry. However, the diagnostic threshold to diagnose instability remains unknown. Objective To compare the syndesmotic area between uninjured participants and patients with syndesmotic injuries using WBCT. Methods Patients aged 14–60 years with suspected syndesmotic injuries were included, with control patients who underwent WBCT for forefoot pathologies. The percentage difference between the injured and uninjured sides was calculated using comparative monopodial WBCT. Results Thirty-eight patients in the study group and twenty-four in the control group were included. Arthroscopy was conducted in six (15.8%) patients, confirming syndesmotic instability. The remaining patients in the study group had stable injuries. The mean percentage area difference from confirmed syndesmal instability, stable syndesmosis, and uninjured ankles was 19.7% (IC 13.2–26.1), 6.8% (IC 0.6–12.9), and 1.46% (IC 0.98–1.94) (p = 0.008). The area under the curve was 0.863, with a sensitivity and specificity of 83.3%, 89.3 respectively. Conclusion Comparative WBCT helps determine the stability of syndesmotic injuries, suggesting that a 19% difference in the syndesmotic area between the uninjured and injured ankles should be used as the cutoff point. Level of Evidence Level III, retrospective, case-control study.