Three-Dimensional Intercondylar Notch Volumes in a Skeletally Immature Pediatric Population: A Magnetic Resonance Imaging–Based Anatomic Comparison of Knees With Torn and Intact Anterior Cruciate Ligaments

Purpose To determine whether 3-dimensional notch volume, measured with magnetic resonance imaging (MRI), differs significantly between knees with torn and intact anterior cruciate ligaments (ACLs) after sports injury in a skeletally immature pediatric population. Methods MRI studies of 50 pediatric patients (age range, 10 to 17 years) with ACL tears were compared with 50 age- and sex-matched intact-ACL control patients. All patients had open physes and underwent MRI after a sports injury. Notch volume was calculated through manual segmentation of notch boundaries seen on axial 1.5-T proton density–weighted images. Two-dimensional (2D) measurements (notch width and notch width index) were made on coronal proton density–weighted MRI studies. Notch volume was compared between groups by use of the Mann-Whitney U test. Pearson correlation coefficients were also calculated between indices. Results Notch volume was significantly lower in knees with ACL tears than in control knees (5.5 ± 1.1 cm3 v 6.4 ± 1.5 cm3 , P = .002), whereas 2D notch width and notch width index did not differ significantly between these groups. Girls had significantly smaller notch volumes than boys (5.4 ± 1.2 cm3 v 6.5 ± 1.3 cm3 , P < .001). Notch volume was not correlated with age but was moderately correlated with 2D notch width ( r = 0.485, P < .001). Conclusions In adolescent patients with sports injuries, the 3-dimensional notch volume was significantly smaller in knees with ACL tears than in intact-ACL control knees. Notch volume was also significantly smaller in girls than in boys and did not vary significantly with age. Level of Evidence Level III, case-control study.