Purpose: This study was done to determine whether a) there is a correlation between the Notch Width Index (NWI) and notch volume, as measured by Magnetic Resonance Imaging (MRI), in patients with ACL-injured and non-ACL injured knees, b) there is a difference in NWI between patients with and without anterior cruciate ligaments tear, c) there is a relationship between ACL diameter, angle of ACL inclination and ACL injury and d) there are differences in distal femur morphology between the ACL-injured and non-ACL injured knees.
Materials and methods: In this study, 59 ACL-injured patients and 59 match-control ACL-intact patients were enrolled. MRI was used to measure the notch width, notch height and condylar widths. The thickness of ACL and ACL angle of inclination were also measured.
Results: Statistically, Notch Width Index (NWI) (0.47 +/- 0.07 vs 0.43+/-0.05, p <0.05) and Medial-condyle to-lateral condyle ratio (M:L ratio) ( 1.07 +/- 0.11 vs 1.02 +/- 0.09, p = 0.023) were all significantly greater in the ACL-ruptured group compared to the ACL-intact group. However the ACL angle of inclination from the vertical axis is statistically significantly smaller in the ACL-injured group compared to the ACL-intact group( 30.729 +/- 6.147 deg vs 43.339 +/- 12.950 deg, p<0.0001).
In both the ACL-injured and ACL-intact groups, the Notch Width (NW), Notch Height (NH) and Notch Volume (NV) measurements were all statistically significantly greater in males compared to females.In both ACL-injured and ACL-intact groups, Notch width indices showed no statistical significant difference between the sexes.
Conclusion: In this MRI study, a high femoral notch width indices and high medial condyle-to-lateral condyle ratio (M:L ratio) serve as accurate predictors in subjects prone to ACL injury. The MRI findings can guide future routine radiological or ultrasound screening of ACL-injury prone knees.
Eric Luis¹* and Mervyn J Cross²