Age- and sex-related MRI developmental patterns of the anterior cruciate ligament, intercondylar notch, and distal femur in children and adolescents

Age- and sex-related developmental patterns of the pediatric knee remain incompletely characterized on routine MRI. MEH may provide continuous quantitative information regarding local distal femoral development, but its association with MRI-defined physeal status remains unclear. To characterize age- and sex-related developmental patterns of ACL morphology, intercondylar notch morphology, medial epiphyseal height (MEH), and MRI-defined distal femoral physeal status in children and adolescents, and to evaluate the association between MEH and physeal status. This retrospective single-center study included 520 children and adolescents aged 6 to 18 years. Knee magnetic resonance imaging was performed to evaluate anterior cruciate ligament morphology, intercondylar notch morphology, medial epiphyseal height, and distal femoral physeal status. Generalized additive models, Spearman correlation, Welch ANOVA, and exploratory receiver operating characteristic analyses were applied for statistical assessment. ACL length and intercondylar notch width increased with age and showed earlier developmental stabilization in females than in males. Distal femoral physeal status progressed with age, with females transitioning earlier toward closing and closed physes. MEH increased with age and was significantly associated with physeal status in the overall cohort and in both sexes. Exploratory ROC analysis yielded AUC values of 0.855 overall, 0.923 in males, and 0.855 in females. Pediatric knee morphology demonstrates distinct age- and sex-related MRI developmental patterns. MEH may complement categorical distal femoral physeal assessment as a continuous quantitative measure of local distal femoral development. These findings characterize age- and sex-related development of the pediatric knee and may serve as a basis for future investigation in skeletally immature patients with ACL injury.