MRI-Based Morphometric Analysis of the Femoral Intercondylar Notch and Its Association With Traumatic Anterior Cruciate Ligament Injury: A Prospective Observational Study in a South Indian Population

INTRODUCTION: Femoral intercondylar notch morphology has been proposed as an intrinsic anatomical risk factor for anterior cruciate ligament (ACL) injury. Magnetic resonance imaging (MRI) provides a reliable and non-invasive method for assessing notch morphometry and related parameters associated with ACL injury risk. METHODS: A prospective observational study was performed on 108 patients aged 18-45 years who underwent knee MRI following traumatic injury. Participants were divided into a normal ACL group (n = 54) and an ACL tear group (n = 54). Morphometric parameters, including notch width (NW), bicondylar width (BW), NW index (NWI), notch angle, and notch shape, were measured on standardized axial MRI images. Continuous variables were analyzed using independent t-tests, and categorical variables were compared using the chi-square (χ²) test. RESULTS: The ACL tear group demonstrated a significantly lower mean NWI compared with the normal ACL group (0.2394 vs. 0.2637; p = 0.00001). Notch angle was also significantly smaller in patients with ACL tears (49.74° vs. 52.33°; p = 0.0056). A-shaped notch morphology showed a strong association with ACL rupture, whereas U-shaped and Ω-shaped notches were more frequently observed in knees with intact ACLs. Age did not show a significant association with ACL injury, while male predominance and right-sided involvement were more common in the ACL tear group. CONCLUSION: Stenotic femoral intercondylar notch characteristics, including reduced NWI, smaller notch angle, and A-shaped configuration, are significantly associated with traumatic ACL injury. MRI-based morphometric evaluation may aid in identifying individuals at increased risk of ACL rupture and support targeted preventive strategies.