The Value Of MRI In Diagnosis Of The Instable Anterior Cruciate Ligament And The Role Of The Mainly Indirect Signs

Objective:To evaluate the value of MRI in diagnosis of the instable anterior cruciate ligament (ACL) and explore the role of the mainly indirect signs.Methods:Seventy-eight patients(eight-four cases of ACL) who met the inclusion criteria were subjected to routine MRI and arthroscopy. All of ACLs were diagnosed on MRI. In comparison with arthroscopy as the gold standard, the values of MRI in diagnosis of the instable ACL and the injuried ACL were evaluated.All of ACLs were divided into the stable ACL group and the instable ACL group. The results of their mainly indirect signs including the posterior cruciate ligament (PCL) angle and PCL curvature index and AT angle (ie the angle of between ACL and the tibia medial platform) between two groups were compared and analyzed statistically.Results:In the list of sensitivity, specificity, accuracy, positive and negative predictive values, P value and Kappa agreement measures, the value of MRI in diagnosis of the instable ACL was higher than those of the injuried ACL.The mainly indirect signs including PCL Angle<1100, PCL curvature index< 3.5 and AT Angle< 500 in the instable ACL group were lower than those in the stable ACL group (P<0.05).Conclusion:(1) It is higher that the sensitivity, specificity and accuracy of MRI in diagnosis of the instable ACL. The direct signs are the most reliable evidence in diagnosis of ACLs.(2) The mainly indirect signs include PCL Angle<110°, PCL curvature index< 3.5 and AT Angle< 500 in the instable ACL group.Whichever of those mainly indirect signs is present, it further proves that the diagnosis of the instable ACL is correct likely.