Value of MRI in diagnosis of anteromedial and posterolateral bundle tears in patients undergoing anterior cruciate ligament reconstruction

Abstract

Objective To analyze the value of MRI in the diagnosis of anteromedial bundle(AMB) and posterolateral bundle (PLB) tears in patients undergoing anterior cruciate ligament (ACL) reconstruction. Methods MRI of 141 knees undergoing ACL reconstruction were retrospectively reviewed with using arthroscopy as golden standard to evaluate diagnostic accuracy of MRI to predict AMB and PLB injury conditions. The interval time between MRI and arthroscopic ACL reconstruction was 4 days to 29 days. The median time was 11 days. The injury patterns of AMB and PLB was observed on MRI and classified into normal type, partial tear and complete tear. Using the arthroscopic findings as the golden standard, MRI diagnostic accuracy of AMB and PLB tears was compared with Chi-square test. Results Thirteen cases(9.2%, 13/141) with isolated bundle injury were identified in the arthroscopic assessments among 141 patients, including 11 cases with isolated AMB injury and 2 cases with isolated PLB injury. Combined AMB and PLB injury were all identified in the remaining 128 knees (90.8%, 128/141). There was statistical difference between the incidence rate of isolated bundle injury and double-bundles injury (χ2=6.532, P=0.011). Partial tear was defined as partially torn or interrupted fiber bundles with remaining normal fiber bundles. Complete tear was defined as the fiber bundles in the expected region of the ligament were completely discontinuous. The diagnostic accuracy of MRI in prediction of AMB injury was better than PLB [85.8% (121/141) versus 72.3% (102/141); χ2=7.737, P=0.005]. There was no statistical difference between the accuracy rate of MRI in diagnosis of partial AMB and PLB tear [77.8% (14/18) versus 50.0% (15/30); χ2=3.630, P=0.057]. There was no statistical difference between the accuracy rate of MRI in diagnosis of complete AMB and PLB tear[87.6% (106/121) versus 84.0% (84/100); χ2=0.589, P=0.443]. There was no statistical difference between the accuracy rate of MRI in diagnosis of partial and complete AMB tear (χ2=1.282, P=0.258). There was statistical difference between the accuracy rate of MRI in diagnosis of partial and complete PLB tear (χ2= 14.690, P=0.001). Conclusions Complete AMB and PLB tear are the common injury patterns among patients undergoing ACL reconstruction, while an isolated AMB or PLB tear is uncommon. MRI is of value in the diagnosis of ACL injury. MRI can accurately diagnose complete AMB tear, complete PLB tear and partial AMB tear, but the diagnostic accuracy of MRI in assessing partial PLB tear needs to be improved. Key words: Anterior cruciate ligament; Wounds and injury; Magnetic resonance imaging