Oblique coronal and oblique sagittal MRI for diagnosis of anterior cruciate ligament tears and evaluation of anterior cruciate ligament remnant tissue.

BACKGROUND The purpose of this study was to investigate the efficacy of additional oblique magnetic resonance imaging (MRI) for the diagnosis of anterior cruciate ligament (ACL) tear and evaluation of ACL remnant tissue. METHODS We retrospectively reviewed the records of 54 knees. Three independent readers evaluated the MR images by the use of three methods: orthogonal sagittal images only (method A); orthogonal sagittal and additional oblique sagittal images (method B); and orthogonal sagittal and oblique coronal images (method C). The sensitivity, specificity, and accuracy for the diagnosis of an ACL tear and the detection of the condition of the ACL remnant tissue by the use of each method were calculated in comparison with arthroscopic findings as the reference standard. RESULTS The arthroscopic records revealed 27 knees with intact ACLs and 27 with torn ACLs. Among the 27 knees with torn ACLs, 9 did not have continuous remnant tissue and 18 had certain remnant tissue attached to the femur or the posterior cruciate ligament. The specificities and accuracies of methods B and C for diagnosing an ACL tear were higher than those for method A. The sensitivity, specificity, and accuracy of method C for the detection of ACL remnant tissue were higher than those for method A and B. CONCLUSIONS Additional use of oblique MRI improved the accuracy of diagnosis of ACL tear and showed a reasonable level of efficacy in detecting ACL remnant tissue. LEVEL OF EVIDENCE Level IV (case series).