Deep lateral notch sign and double notch sign in complete tears of the anterior cruciate ligament: MR imaging evaluation

Objective To systematically compare the notches of the lateral femoral condyle (LFC) in patients with and without complete tears of the anterior cruciate ligament (ACL) in MR studies by (1) evaluating the dimensions of the lateral condylopatellar sulcus; (2) evaluating the presence and appearance of an extra or a double notch and its association with such tears. Materials and methods This retrospective study was approved by our institutional review board, and informed written patient consent was waived. In 58 cases of complete ACL tears and 37 control cases with intact ACL, the number of notches on the LFC was determined, and the depth and anteroposterior (AP) length of each notch were measured in each third of the LFC. The chi-square test, t -test, and logistic regression model were used to analyze demographic data and image findings, as appropriate. Results Presence of more than one notch demonstrated a sensitivity of 17.2 %, specificity of 100 %, positive predictive value of 100 %, and negative predictive value of 43.5 % for detecting a complete ACL tear. Lateral third depth measurement ( p = 0.028) was a significant associated finding with a complete ACL tear. Conclusion A deep notch in the lateral third of the LFC is a significant associated finding with a complete ACL tear when compared with an ACL-intact control group, and the presence of more than one notch is a specific but insensitive sign of such a tear.