Accuracy of magnetic resonance imaging for meniscal body tear in anterior cruciate ligament-deficient knees compared to anterior cruciate ligament-intact knee

Abstract

Objectives: This prospective case–control study was conducted with primary aim to compare the value of magnetic resonance imaging (MRI) in terms of accuracy, sensitivity, specificity, positive predictive value, and negative predictive value for the detection of meniscal tear in anterior cruciate ligament (ACL)-deficient and ACL-intact groups. The secondary aim was to identify if the sensitivity and accuracy differ if the MRI is older than 3 months from the time of surgery. Materials and Methods: There were 255 patients enrolled into this study out of which 207 fulfilled the inclusion criteria. Among 207, 138 underwent surgery within 1 month of MRI, 30 had 1–3 months delay, and 39 cases underwent surgery more than 3 months after their MRI. Among 167 patients who underwent surgery within 3 months of MRI, 97 had ACL tear and 71 had intact ACL. Results: The overall sensitivity for lateral meniscus tear (68.2%) is significantly lower than the medial meniscus tear (92.9%). The sensitivity of MRI for medial meniscus tear in ACL-deficient knee is lower than ACL-intact knees (90% vs. 96.2%, P = 0.3). Similarly, the sensitivity is significantly lesser for lateral meniscus tear in ACL-deficient knee compared to ACL-intact knee (50% vs. 83.3%, P = 0.009). The sensitivity of MRI for both the lateral and medial meniscus tear decreased if the MRI performed 3 months before the surgery. Conclusion: Patients with ACL-deficient knee have to be counseled for intraoperative detection of lateral meniscus tear as the sensitivity of MRI for lateral meniscus tear in ACL-deficient group is low. Similarly, if the MRI is more than 3 months old from the time of surgery, we recommend to repeat the MRI as the sensitivity decreases significantly.