Functional Outcomes of All-Inside Arthroscopic Repair for Chronic Ankle Instability in Adolescents: A Case Series.

Introduction: Lateral ankle sprain is among the most common orthopedic injuries and may progress to chronic ankle instability (CAI), particularly in adolescents engaged in sports. Approximately 20-40% of patients with acute ankle sprains develop CAI, which is associated with recurrent instability, pain, and impaired athletic performance. Evidence regarding the surgical management of CAI in the pediatric population remains limited. This study aimed to evaluate the functional outcomes of arthroscopic all-inside ligament repair in adolescents with CAI refractory to conservative treatment. Materials and Methods: A retrospective observational case series was conducted between January 2024 and May 2025. Patients younger than 16 years with CAI unresponsive to at least 6 months of conservative management and with a minimum post-operative follow-up of 12 months were included. Demographic variables and time to return to sports were recorded. Functional outcomes were assessed using the American Orthopaedic Foot and Ankle Society (AOFAS) Ankle-Hindfoot Score and the Karlsson-Peterson Ankle Score, measured preoperatively and at 3, 6, and 12 months postoperatively. Statistical analysis was performed using the Friedman test with Wilcoxon signed-rank post hoc comparisons and Kendall's W for effect size. Results: Five patients (2 males, 3 females; mean age 14.4 ± 0.8 years) were included. All returned to sports at a mean of 2.8 months postoperatively. No complications were reported. The mean baseline AOFAS score was 71.0 ± 8.2, improving to 98.0 ± 4.4 at 3 months and reaching 100.0 at 6 and 12 months. The Karlsson-Peterson score increased from 61.2 ± 10.7 at baseline to 93.0 ± 5.7 at 3 months and 100.0 at subsequent follow-ups. The Friedman test demonstrated significant differences across time points (AOFAS: χ2 = 13.62, P = 0.0035; Karlsson- Peterson: χ2 = 15.00, P = 0.0018), with Kendall's W = 1.0 indicating a very large effect size. Conclusion: Arthroscopic all-inside ligament repair in adolescents with CAI refractory to conservative management yielded excellent functional outcomes, early return to sports, and no complications. Anchor size selection was critical to avoid physeal injury and peroneal tendon irritation. These findings support the feasibility and safety of minimally invasive ligament repair in skeletally immature patients, although larger studies with longer follow-up are warranted to confirm durability and generalizability.