A Field-Side Triage Model for Early Specialist Referral After Acute Lower Extremity Sports Injuries in Young Athletes: Development and Internal Validation

Abstract Objective To develop and internally validate a field-side triage model to support early specialist referral decisions in young athletes with acute lower extremity sports injuries, where diagnostic resources are often limited. Design Retrospective cohort study. Setting Single-center sports medicine clinic. Participants Athletes aged ≤22 years presenting with acute lower extremity sports injuries between January 2017 and November 2025. Independent Variables Age, sex, functional severity, injury site, and injury mechanism assessed at initial presentation. Results A total of 2,129 athletes were included, with 276 (13.0%) undergoing surgery. Independent predictors were older age, female sex, greater functional severity, knee involvement, and high-energy deceleration mechanisms. The full model showed good performance (AUC 0.890; Brier score 0.073; calibration slope 1.00), and the simplified model also demonstrated high discrimination (AUC 0.883). Risk stratification showed increasing surgical rates across low-, intermediate-, and high-risk groups. Decision curve analysis demonstrated greater net benefit than treat-all and treat-none strategies across clinically relevant thresholds. Conclusions A field-side prediction model based on readily obtainable clinical variables demonstrated good performance for identifying young athletes at risk of requiring surgical intervention and may support early specialist referral decisions in resource-limited settings. Clinical Relevance This model provides a practical tool for early risk stratification using simple clinical information, supporting timely and appropriate referral decisions in field-side and initial clinical settings.