Anterior cruciate ligament volume: analysis of gender differences

In this study, gender differences in the anterior cruciate ligament (ACL) were assessed with high resolution MRI. Using a quadrature extremity coil at 1.5T, volumes of the separate bundles of the ACL (anteromedial [AMB] and posterolateral [PLB]) were measured with shaded surface three-dimensional (3D) reconstruction in 63 knees (33 male, 30 female). Bundle volumes were measured from consecutive fat-suppressed fast spin-echo proton-density coronal MR images and intraobserver reproducibility was recorded. The data were divided into subgroups based on gender, age, height, weight, and body mass index (BMI) for statistical analysis. Results of the study revealed the mean ACL volume to be significantly different for males (1.07 cc) and females (0.77 cc) (P = 0.0025), yet when adjusting for body height differences, these were no longer significantly different. Mean AMB volume was smaller than the PLB volume for females (0.33 cc vs. 0.44 cc; P < 0.0001) and males (0.49 cc vs. 0.58 cc; P < 0.0001). Correlation coefficients were highest for height (r = 0.597) and weight (r = 0.5371) and regression analysis revealed height to be the most significant factor affecting ACL volume. Intraobserver measurements were reproducible (r = 0.90). From this data, we conclude that gender differences in ACL volume are present, but may be accounted for by height differences between males and females.