Size and Morphology of the Anterior and Posterior Cruciate Ligaments at Different Pediatric Age Intervals: An MRI Analysis

BACKGROUND: The incidence of anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL) tears in children and adolescents has increased over the past decade, with increasing numbers of ACL and PCL reconstructions in this patient population. PURPOSE: To evaluate the size and morphology of both the ACL and the PCL by magnetic resonance imaging (MRI) in different pediatric age groups. STUDY DESIGN: Cross-sectional study; Level of evidence, 3. METHODS: MRI examinations of 127 knees (67 female, 60 male; aged 0-18 years) were analyzed retrospectively. The cohort was split into 6 age subgroups, 1 subgroup for every 3 years (minimum 8 patients per subgroup). The following parameters were measured by 2 independent raters at 2 different time points: ACL length, anteroposterior and mediolateral ACL width, sagittal and coronal ACL inclination, inclination of the intercondylar notch, bicondylar width, notch width, coronal ACL and PCL width, PCL length, and sagittal width of the lateral femoral condyle. The following indices, areas, and volumes were calculated: sagittal width of the lateral femoral condyle/PCL length, ACL area and volume, notch width index, ACL width/notch width, PCL width/notch width, ACL width/bicondylar width, and PCL width/bicondylar width. A correlation analysis was performed for patient age, height, weight, and body mass index (BMI). RESULTS: ACL length was between 18 and 37 mm, and ACL width was between 4 and 6 mm. PCL length ranged between 27 and 43 mm, while PCL width was between 7 and 9 mm. Growth of the cruciate ligaments was the most pronounced between the ages of 4 and 12 years. Correlations with size and weight were strong, while BMI correlated slightly with the measurements. Measurements in female patients were slightly larger than in their male counterparts between the ages of 0 and 6 years, while male patients tended to have larger values starting from ages 7 to 9 years. These values were significantly larger in male patients from the ages of 16 to 18 years (P < .05). CONCLUSION: This study provides normative data on the morphology of pediatric anatomic features in the knee as a basis for age-appropriate and individualized surgical care of ACL and PCL injuries in children and adolescents.