Increased Lateral and Medial Femoral Posterior Radius Ratios Are Risk Factors for Anterior Cruciate Ligament Injury

Abstract

Background Many studies have shown that the distal femoral sagittal morphological characteristics had a clear relationship with knee joint kinematics. The aim of this study was to determine the relationship between distal femoral sagittal morphological characteristics and noncontact anterior cruciate ligament (ACL) injury. Methods A retrospective case-control study of 148 patients was conducted. Two age- and sex-matched cohorts (each n = 74) were analysed: a noncontact ACL injury group and a control group. The lateral femoral posterior radius (LFPR), medial femoral posterior radius (MFPR), lateral height of the distal femur (LH), medial height of the distal femur (MH), lateral femoral anteroposterior diameter (LFAP), medial femoral anteroposterior diameter (MFAP), lateral femoral posterior radius ratio (LFPRR), and medial femoral posterior radius ratio (MFPRR) were compared between the two groups. Receiver operating characteristic (ROC) curve analysis was used to evaluate the significance of the LFPRR and MFPRR in predicting ACL injury. Results Compared with patients in the control group, patients in the ACL injury group had an increased LFPR, MFPR, MFAP, LFPRR, and MFPRR. ROC curve analysis revealed that an increased LFPRR above 31.7% was associated with noncontact ACL injury, with a sensitivity of 78.4% and a specificity of 58.1%, and an increased MFPRR above 33.4% was associated with noncontact ACL injury, with a sensitivity of 58.1% and a specificity of 70.3%. Conclusion This study showed that increased LFPRR and MFPRR were risk factors for noncontact ACL injury. These data could help identify individuals susceptible to ACL injuries.