ACL Injuries by MRI: How Can Indirect Signs Confirm our Diagnosis?, SAMIRA SARAYA and MOHAMED T. ALY
Abstract
Aim of Study: Our study aiming to find a reliable method for ACL injuries diagnosis to minimize the surgical intervention in unneeded cases.
Material and Methods: This study includes 192 individuals with mean age of 29.9 years (age ranging from 14 to 73 years). All of them underwent arthroscopic evaluation for clinically suspected ACL tear at the orthopedic department of our institute. Their MR images were reviewed retrospectively by two radiologists blind to the arthroscopy results, clinical history and the initial MR imaging interpretations. All of those patients were evaluated for the indirect signs including: Bone contusions (either femoral or tibial or both), lateral femoral sulcus sign, ACL orientation (using relation to tibial plateau and to blumensaat line), PCL angle, anterior tibial drawer and Segond fracture.
Results: Femoral and/or tibial bone contusions show high sensitivity and specificity in the diagnosis of complete thickness tear while only tibial contusions were of significant value in the partial tears.
On cut off value of 5 degrees to the ACL Blumensaat angle the sensitivity and the specificity were 100% and 99% respectively in the diagnosis of the full thickness tears while they were 67% and 71% in the partial thickness tears. In addition, the anterior tibial drawer showed sensitivity and specificity of 100% and 85% respectively in full thickness tears when we used a cut off value of 3.5cm.
Alternatively using cut off values of 46.5 degrees for the ACL tibial angle and 111.5 degrees for the PCL angle are conclusive of normal ACL with sensitivity and specificity of 95%, 84% and 100%, 84% respectively.
Conclusion: Indirect signs for assessment of ACL tear are beneficial in the diagnosis of complete tears yet they are not conclusive in the partial tears. Also we can use the PCL and ACL-tibial angles with cut off values of 46.5 degrees and 111.5 degrees respectively to diagnose cases with intact ACL as a trial to reduce unnecessary arthroscopy.