MRI Diagnosis Of Tears Of Knee Anterior Cruciate Ligament

Objective:To use the findings of arthroscopy as the standard reference,assess the value of MR imaging in diagnosis of tears of the anterior cruciate ligament(ACL) of the knee and explore why gave rise to MRI false-positive and false-negative.Methods:72 patients who had been highly suspected internal derangement of the knee was performed both MRI and arthroscopy examination. The MR images were prospectively interpreted and analyzed for accuracy of MR diagnosis of ACL tears. To measure posterior cruciate ligament angle, posterior cruciate ligament curvature index and the angle formed by the intersection between the anterior cruciate ligaments and the medial tibial plateau(AT angle),respectively.Results: 54 patients with ACL tears and 18 patients with ACL normalconfirmed by arthroscopy.23 partial tears and 21 complete tears in all of ACL tears .The sensitivity,specificity ,accuracy, positive predictive value and negative predictive value of MR diagnosis of ACL tears were 90.74%,88.89%,87.5%.respectively . On sagittal imagines , PCL angle of complete injuried ACL was 103.2±5.13°,PCL index was 3.18±0.33,AT angle was41.03±4.16°respectively.PCL angle of partial injuried ACL was 116.76±6.15°, PCL index was 4.26±0.38, AT angle was55.28±3.52°respectively. PCL angle of normal ACL was117.39±5.59°, PCL curvature index was 4.38±0.35, AT angle was 57.78±3.93°respectively. There was no significant difference between three indexs of partial injuried ACL and normal ACL(p > 0.05); there was significant difference between these indexs of complete injuried ACL and normal ACL(p<0.05); there was significant difference betweenthese indexs of complete injuried ACL and partial injuried ACL(p<0.05),respectively.Conclusions: 1.MR imaging is an effective tool in the detection of ACL tears.2. Complete ACL tears have conspicucus direct signs and indirect signs MRI,which could be easily diagnosed. However,indirect signs of injuried ACL on MRI is important.But the accuracy of MR imaging for diagnosis of Partial tear of ACL were decreased. The diagnosis of partial ACL tear was unconspicuous direct signs and few indirect signs,which may gave rise to MRI false-positive and false-negative.3.The smaller of the PCL angle,the PCL curvature index and AT angle the more possibility of ACL tears, especially ACL Complete tears.