BACKGROUND: Currently, there is no established preoperative clinical tool for determining whether to opt for surgical reconstruction or repair in cases of chronic ankle instability. HYPOTHESIS: This study aimed to develop a predictive score for the likelihood of instability recurrence after surgical repair. PATIENTS AND METHODS: A multicenter case-control study was conducted, comparing patients who experienced recurrence of instability after surgical repair of the lateral ankle ligament (ATFL) to those who did not experience recurrence within 2 years post-surgery. Preoperative risk factors associated with instability recurrence at the 2-year mark were identified. Utilizing these datas along with existing literature, the Ankle Instability Severity Score (AISS) for predicting the risk of recurrence after ATFL repair was formulated. Subsequently, this score was calculated for all patients in the study cohort to evaluate its predictive capability. RESULTS: Gender (p = 0.03), age (p = 0.02), BMI (p = 0.02), and participation in pivot sports (p = 0.04) were identified as risk factors for recurrence. The 9-point AISS score was applied to the patient cohort. When the score was three or lower, the recurrence rate after ATFL repair stood at 10.6% (OR 0.11 [0.04
0.28], p <
0.001). Conversely, if the score exceeded five, the recurrence rate was substantially higher at 80.0% (OR 11.9 [1.67
237.0], p = 0.03). Using ROC analysis, a threshold value of AISS score at 3.5 (sensitivity = 77.4%, specificity = 72.8%, AUC = 0.78) was identified to develop a instability recurrence after surgical repair. DISCUSSION: This study introduces the AISS score, which relies on straightforward preoperative criteria to assist in deciding whether patients with chronic ankle instability should undergo ligament repair surgery or explore alternative treatment options. LEVEL OF EVIDENCE: IV
retrospective study.