Preoperative MRI Signal Intensity of the Anterior Talofibular Ligament Is Not Associated With Mid- to Long-term Outcomes After Modified Broström Procedure in Adolescents With Chronic Lateral Ankle Instability: A Propensity-Matched Cohort Analysis

Background: The signal-to-noise ratio (SNR) of the anterior talofibular ligament (ATFL) on preoperative magnetic resonance imaging (MRI) has been shown to influence outcomes after the modified Broström procedure in adults with chronic lateral ankle instability (CLAI). Its prognostic value in adolescents remains unclear. This study was to evaluate the relationship between preoperative ATFL-SNR and mid- to long-term clinical outcomes following modified Broström repair in adolescents with CLAI. Methods: This retrospective cohort study included adolescents who underwent modified Broström repair between July 2015 and June 2020. ATFL-SNR was measured on preoperative MRI and categorized into low (LSNR, SNR < 10.4) and high (HSNR, SNR ≥ 10.4) groups. Propensity score matching (1:1) was used to balance age, sex, body mass index, symptom duration, side, joint hypermobility, and preinjury Tegner score. Patient-reported outcomes (PROs) include visual analog scale (VAS) for pain, Karlsson score, Tegner score, and Foot and Ankle Outcome Score (FAOS, as the primary outcome). Secondary outcomes included time to return to sport, recurrent sprain, incision numbness, and subjective satisfaction. Linear regression and subgroup analysis were conducted. Results: Seventy-eight patients (39 per group) were included, with a mean follow-up of 80.3 ± 17.7 and 80.1 ± 18.1 months in the LSNR and HSNR group ( P = .950). Both groups showed significant improvements in all PROs ( P < .05), but no significant differences were observed between the LSNR and HSNR groups (all P > .05). Return to sport time, recurrent sprain rate, numbness, and satisfaction rate were also comparable. No correlations were found between ATFL-SNR and postoperative PROs. Subgroup analyses showed no association between comorbidities and postoperative FAOS scores. Conclusion: Preoperative ATFL signal-to-noise ratio (SNR) on MRI was not associated with mid- to long-term outcomes after modified Broström repair in adolescents with chronic lateral ankle instability. These estimates should be interpreted with caution given the relatively small sample, potential residual confounding, and SNR variability. Within this cohort, favorable long-term outcomes were achieved across the range of preoperative SNR values.