Objectives: The purpose of this study was to identify prospectively the anatomical and functional intrinsic risk factors for lateral ankle sprain (LAS) in adolescent athletes participating in team sports. Design: A prospective cohort study. Setting: University research laboratory. Participants: A total of 152 adolescent male athletes (age: 14.45 ± 2.96 years; height: 165.63 ± 15.33 cm; weight: 55.60 ± 16.56 kg; body mass index: 19.97 ± 3.58 kg/m2) participated in this study. Main outcome measures: The participants were assessed during the preseason for previous ankle sprain history, navicular drop, tibia vara, Q angle, tibia torsion, knee recurvatum, and ankle ROM. LASs were prospectively recorded and diagnosed for two consecutive seasons (20 months). Results: Previous ankle sprain history (odds ratio [OR] ¼ 60.911, p < 0.001), increased navicular drop (OR ¼ 1.767, p < 0.001), and knee recurvatum (OR ¼ 1.881, p ¼ 0.002) were positively associated with the incidence of LAS. The receiver operating characteristic (ROC) analyses revealed the predictive potentials of previous ankle sprain history (the area under the ROC [AUROC] ¼ 0.706, p < 0.001), navicular drop (AUROC ¼ 0.906, p < 0.001), and knee recurvatum (AUROC ¼ 0.724, p < 0.001). Conclusion: Athletes with previous ankle sprain history, knee recurvatum, and especially navicular drop may have a greater risk of LAS injury. The data from this study can help therapists and trainers to identify people with a higher risk of LAS
