Risk Factors for Chronic Syndesmotic Instability After the First Episode of Acute Ankle Sprain: A Cross-Sectional Study of 356 Cases.

Abstract

Chronic syndesmotic instability (CSI) can be associated with severe long-term pain and disability. This study aimed to investigate the risk factors associated with the development of CSI in patients who underwent conservative treatment after the first episode of acute ankle sprain (AAS) that did not result in a satisfactory outcome. We retrospectively analyzed the clinical data of patients who underwent ankle arthroscopy for suspected CSI between January 2020 and September 2023. The patients were divided into the instability and stability groups based on the syndesmotic space width measured under arthroscopy, with 3 mm as the critical value. Demographic, arthroscopic, and imaging information such as the anterior talofibular ligament (ATFL), calcaneofibular ligament, posterior talofibular ligament (PTFL), anterior inferior tibiofibular ligament (AITFL), posterior inferior tibiofibular ligament (PITFL), deltoid ligament (DL), interosseous membrane, height of the syndesmotic fluid, injuries of the talus, calcaneus, tibia, and fibula, effusion of the tibiotalar and talocalcaneal joints, fibular morphology, and fibular incisura features, were recorded. Univariate and multivariate analyses were performed successively to identify the risk factors. Of the 356 patients, 102 developed CSI after the first episode of AAS. In the multivariate analysis, development of CSI was associated with 5 clinical factors: DL injury (odds ratio [OR] 7.453, 95% CI 3.007-18.471; <i>P</i> < .001), positive bandage-binding test (OR 7.196, 95% CI 2.942-17.599; <i>P</i> < .001), grade 2 to 3 injury of the PITFL (OR 2.727, 95% CI 1.044-7.124; <i>P</i> = .041), positive squeeze test (OR 2.455, 95% CI 1.045-5.770; <i>P</i> = .039), and body mass index (BMI) (OR 1.306, 95% CI 1.121-1.522; <i>P</i> < .001). Five key factors were associated with CSI development in patients who underwent conservative treatment after the first episode of AAS that did not result in a satisfactory outcome: DL injury, positive bandage-binding test, grade 2 to 3 injury of the PITFL, positive squeeze test, and BMI.