Our objective was to study the influence of the inter-condylar notch (ICN) geometry on the risk of anterior cruciate ligament (ACL) rupture. We conducted a retrospective and comparative case-control study. Our series has included 80 patients divided into two groups. The patients in group 1 (40 cases) had unilateral ACL rupture. Group 2 included 40 patients with a healthy ACL. The geometry of the notch was evaluated through the Notch width Index (NWI), the notch shape index (NSI) and the notch height index (NHI). The primary judgment criterion is a lower NWI in group 1. These parameters have been calculated on SHUSS radiography of the knee and on frontal MRI cross section. The comparative analysis of the three parameters of the inter-condylar notch has shown that the average NWI (radiological and MRI) and NHI of group 1 were lower than those of the Group 2 with a statistically significant difference. The difference between the NSI averages for the two groups was not statistically significant. We have found a correlation between the values of the radiological NWI and the values of the NWI (MRI). In conclusion, a narrow inter-condylar notch in width (NWI < 0.22) or height (NHI < 0.44) represents a risk factor of ACL rupture. The threshold, from which we talk of a pathological ICN, must be adapted to the population concerned because studies have shown a variation of measurements between different ethnic groups.