Axial and Sagittal Knee Geometry as a Risk Factor for Noncontact Anterior Cruciate Ligament Tear: A Case-Control Study

Purpose The purpose of this study was to compare the axial and sagittal geometry of the distal femur and proximal tibia in men and women with and without noncontact anterior cruciate ligament (ACL) tears to determine whether a difference existed in these groups. Methods Twenty men and 20 women with noncontact ACL tears and preoperative magnetic resonance imaging scans of their knees were compared with 20 men and 20 women who had magnetic resonance imaging for meniscal pathology. Patients were not matched for age, weight, or height. We measured the anteroposterior dimensions of the femoral condyles, the medial-lateral width of the femur, and the angle of intersection between the transepicondylar axis and the long axis of the femoral condyles. We also measured the anteroposterior dimension of the tibial plateaus, as well as the width of the proximal tibia. Finally, the posterior tibial slope was measured for the medial and lateral tibial plateaus. All dimensional measurements were standardized and compared statistically. Results When compared with normal men, normal women had proportionally deeper medial (3%, P = .049) and lateral (7%, P < .001) femoral condyles, as well as deeper medial tibial plateaus (5%, P = .025). There were no differences between normal women and women with ACL tears ( P = .09 to .83). Men with ACL tears had deeper medial (5%, P = .04) and lateral (10%, P = .01) tibial plateaus, as well as an increased posterior slope of the lateral tibial plateau (12° vs 8°, P = .006), when compared with normal men. Conclusions We compared normal men and women with those with noncontact ACL tears and found that women's knees were characterized by proportionally deeper medial and lateral femoral condyles, as well as deeper medial tibial plateaus. When compared with normal men, men with ACL tears had deeper medial and lateral tibial plateaus, as well as an increased posterior slope of the lateral tibial plateau. Level of Evidence Level III, case-control study.