Diagnostic Accuracy of Magnetic Resonance Imaging in the 120° Flexed-Knee Position for Detecting and Classifying Meniscal Ramp Lesion

Background: Detection of meniscal ramp lesions concomitant with anterior cruciate ligament (ACL) injury using conventional magnetic resonance imaging (MRI) has low sensitivity, and these lesions are currently difficult to diagnose preoperatively. Purpose/Hypothesis: The purpose of this study was to assess the accuracy of MRI in detecting the presence of meniscal ramp lesions in the 120° flexed-knee position compared with that in the near–extended-knee position. It was hypothesized that the diagnostic performance of MRI in the 120° flexed-knee position would be better than that in the extended-knee position. Study Design: Cohort study (Diagnosis); Level of evidence, 2. Methods: This retrospective study of prospectively collected data between February 2019 and January 2024 included 154 consecutive patients undergoing ACL reconstruction. All patients underwent 3-T MRI examination in the near extended- and 120° flexed-knee positions preoperatively. The presence and Thaunat classification of ramp lesions were separately detected on each MRI scan and confirmed via arthroscopy during ACL reconstruction. Diagnostic sensitivity, specificity, and conditional relative odds ratios for detecting ramp lesions and the classification accuracy were compared between 2 MRI modalities. The accuracies of these MRI scans in acute and chronic cases were also evaluated. Results: This study included 154 patients (79 male and 75 female; mean age, 29.0 ± 14.2 years). A total of 62 ramp lesions (40.3%) were observed on arthroscopy. The sensitivity and specificity of MRI in near extension were 69.4% and 77.2%, respectively, and those in flexion were 91.9% and 94.6%, respectively, with significant superiority in MRI at knee flexion ( P = .003 and P < .001, respectively). The conditional relative odds ratio between the MRI examinations at these 2 positions was 10.3 (95% CI, 4.82-21.8). The classification accuracy of MRI in flexion was significantly higher than that of MRI in near extension (accuracy, 49 vs 11; P < .001). The diagnostic accuracy of MRI in the 120° flexed-knee position was significantly higher than that in the near–extended-knee position in the acute cases ( P < .05); however, no significant differences were observed in the chronic cases. Conclusion: The diagnostic accuracy of MRI in the 120° flexed-knee position for detecting and classifying meniscal ramp lesions was superior to that of MRI in the near–extended-knee position.