LCL IN A SINGLE CORONAL SLICE – A NOVEL SIGN FOR IDENTIFYING ACL DEFICIENT PATIENTS AND PREDICTING RISK OF FUTURE GRAFT FAILURE

Background: The ACL deficient knee is predisposed to anterior translation and internal rotation of the tibia. Hypothesis/Purpose: To show that knee deformity in an ACL deficient knee will produce a more vertical orientation of the lateral collateral ligament (LCL), allowing for the entire length of the LCL to be visualized on a single coronal slice (coronal LCL sign) on MRI, and that this sign is indicative of a greater risk for graft failure after ACL reconstruction. Methods: Charts were retrospectively reviewed to create 3 separate cohorts: normal ACL and no pathology involving the collateral ligaments (control cohort), ACL reconstruction without evidence for graft rupture, and ACL reconstruction with graft failure. Tibial translation and femorotibial rotation were measured on MRI, and posterior tibial slope was measured on lateral knee radiographs. Imaging was reviewed for the presence of the coronal LCL sign. Results: Deficient ACL (n=153) compared with intact ACL (n=70) was associated with significantly greater displacement regarding anterior translation (5.8mm internal rotation vs 0.3mm external rotation, p