Correlation between knee anatomical angles and anterior cruciate ligament injury in males

To determine the correlation between anatomical angles of knee joint and anterior cruciate ligament (ACL) injury, and evaluate the effects of these angles on identifying people prone to ACL injury in males.

From January 2013 to October 2017, male patients with and without non-contact ACL injury were included in the case and control groups, respectively. Anatomical angles on the sagittal and coronal magnetic resonance (MR) images of these patients were measured by senior radiologist and orthopaedic surgeon. The parameters contained medial tibial slope (MTS), lateral tibial slope (LTS), medial-lateral plateau slope (MLPS), femoral axis-Blumensaat line angle (FABA), anterior tibia slope (ATS), anterior tibial-Blumensaat line angle (ATBA). The Student's-t test or rank sum test was used to compare the independent samples between different groups. Binary logistic regression analysis was used to analyse the effects on identifying people apt to suffer an ACL injury of these angles.

A total of 150 male patients were included in the study. There were 72 patients in the case group and 78 patients in the control group. The MTS, LTS and ATBA in the case group were significantly greater than those in the control group (P = 0.021, P < 0.001, P = 0.046). The FABA of the case group was significantly smaller than that of the control group (P = 0.006). There was no significant difference in MLPS and ATS between the two groups. The area under the curve (AUC) of LTS was 0.762, the best anatomical angle for identifying people prone to ACL injury. Combining these anatomical angles can improve the accuracy (AUC = 0.800).

The male ACL injury was associated with MTS, LTS, ATBA and FABA of the knee. The LTS might be more suitable for predicting ACL injury. Analysis of these angles alone or in combination could help identify the people apt to suffer ACL damage.