Investigating the Role of Proximal Femoral Morphology in Noncontact ACL Injuries: A Comparative Study

Abstract

Background: Non-contact anterior cruciate ligament (ACL) injury is a common and debilitating injury among athletes, with high recurrence rates and long-term consequences. Identifying individuals at risk of ACL injury can help prevent or reduce the severity of these injuries. The present study aimed to assess the alpha angle in ACL rupture patients in both the injured (ipsilateral) and non-affected (contralateral) extremities, compared to a control group. Methods and Results: This case-control study included 105 subjects (78.1% male and 21.9% female) aged between 15 and 45 years of both sexes involved in sports. The case group consisted of 54 patients with sport-related, noncontact ACL ruptures identified by MRI. Fifty-one patients, 10(19.6%) of whom were female, with no ACL rupture, were included in the study as a control group. Hip radiographs were taken in all the subjects using the modified Dunn View with the patient in the supine position, hip flexed 45o and abducted 20o. OsiriX software was used to obtain the measurements. Most injuries were caused by football (58.1%), followed by jumping sports (23.8%) and skiing (18.1%). The mean alpha angle was 49.27o (SD=4.93) for subjects without ACL rupture and 54.84o (SD=6.17) for subjects with ACL rupture, and the difference was statistically significant (P<0.001). Results also showed a statistically significant difference in the alpha angle on the ipsilateral (54.84o [SD=6.17]) and contralateral (49.48o [SD=7.04]) hips of the case subjects (P<0.001). The logistic regression analysis indicated a statistically significant difference in alpha angle between the case and control groups and between hips of the same subject with an OR of 1.12 (P=0.041) and 1.2 (P=0.000), respectively. Conclusion: Alterations in proximal femur morphology should be considered a potential risk factor for ACL injury, and alpha angle can be a significant predictor of ACL injury. We recommend that young athletes actively participating in sports have their hip alpha angle measured so those with higher alpha angle can follow special prevention programs.