Abstract / Summary
Abstract Background： Pediatric anterior talofibular ligament (ATFL) injuries differ from those in adults, with avulsion injuries occurring frequently at the ligament attachment sites. Small avulsion fractures may be difficult to detect, while objective imaging parameters for treatment planning and follow-up remain limited. This study evaluated the diagnostic and prognostic utility of high-frequency ultrasound (US) in pediatric ATFL injuries. Methods： We retrospectively analyzed 194 pediatric patients with ATFL injuries who underwent high-frequency US between December 2024 and March 2026. Thirty-two surgically treated patients were included in a diagnostic comparison of US and magnetic resonance imaging (MRI), using intraoperative findings as the reference standard. Forty-two patients with ATFL avulsion fractures treated conservatively and followed by US for 3 months were included in the prognostic analysis. The sensitivity and specificity of US and MRI for complete ATFL tears and avulsion fractures were assessed. The avulsion fracture separation distance was measured on US, and its ability to predict healing was evaluated using receiver operating characteristic (ROC) analysis. Measurement reproducibility was assessed using intraclass correlation coefficients (ICCs). Results： Among the 194 patients, avulsion fracture was the predominant injury pattern, occurring in 129 (66.5%). In the surgical cohort, complete ATFL tears were confirmed in 6 patients and avulsion fractures in 26. For complete tears, US showed a sensitivity of 83.3% compared with 66.7% for MRI. For avulsion fractures, US demonstrated 100% sensitivity versus 80.8% for MRI, with 100% specificity for both modalities. Among the 42 conservatively treated patients, 25 (59.5%) demonstrated healing at 3 months. Avulsion fracture separation distance showed excellent predictive performance for healing (AUC, 0.935; 95% CI, 0.814–0.988; P < 0.001). A cutoff of ≤0.95 mm yielded 92.0% sensitivity and 82.4% specificity. Interobserver and intraobserver agreement were excellent (ICC, 0.962 and 0.971, respectively). Conclusions： High-frequency US provides sensitive detection of pediatric ATFL avulsion fractures and enables quantitative assessment of avulsion fracture separation. A separation distance of ≤0.95 mm was associated with a higher likelihood of healing after conservative treatment. High-frequency US may therefore provide orthopedists with practical diagnostic and prognostic information to support treatment planning and follow-up in pediatric ATFL injuries.