The anterior talofibular ligament-posterior talofibular ligament angle decreased after ankle lateral stabilization surgery.

PURPOSE: The angle between the anterior talofibular ligament (ATFL) and the posterior talofibular ligament (PTFL) is increased in patients with chronic ATFL injury. This study aimed to compare the AFTL-PTFL angle before versus after ankle lateral stabilization surgery, and to evaluate whether the ATFL-PTFL angle correlates with the ligament injury severity. METHODS: This retrospective study included 48 patients with mechanical ankle instability treated between 2016 and 2018. After arthroscopic evaluation, all patients underwent ankle lateral stabilization surgery comprising ligament repair (n = 28) or reconstruction (n = 20). The ATFL-PTFL angle was measured in the axial plane on pre- and postoperative MRI. Comparisons were made of the pre- versus postoperative ATFL-PTFL angles, and the ATFL-PTFL angle of the repair versus reconstruction groups. Receiver operating characteristic (ROC) curve analysis was used to assess the diagnostic performance of the ATFL-PTFL angle in selecting the surgical technique. RESULTS: The postoperative ATFL-PTFL angle was significantly decreased compared with preoperatively. The ATFL-PTFL angle was significantly smaller in the repair group than the reconstruction group preoperatively and postoperatively. The area under the ROC curve was 0.741 (P < 0.01). The optimal cutoff point for the selection of ligament reconstruction was an ATFL-PTFL angle of 89.4° (sensitivity 0.85, specificity 0.61). CONCLUSION: The ATFL-PTFL angle decreases after ankle lateral stabilization surgery. The ATFL-PTFL angle is related to the severity of the ATFL injury. Ankle lateral ligament reconstruction should be considered when the ATFL-PTFL angle is > 89.4°. LEVEL OF EVIDENCE: Level III.