Anterior cruciate ligament tears: Primary and secondary signs at MR imaging

Abstract

Background: Injury of the Anterior Cruciate Ligament (ACL) is one of the most frequently encountered knee and ligamentous injuries. MR imaging is an excellent modality for detecting ACL tears. There are several primary and secondary signs of ACL tear. Subjects and Methods: We retrospectively collected data of cases with ACL tear in the Department of Radio-Diagnosis in Rajrajeswari Medical College, Bangalore and studied the primary and secondary signs of ACL tear. Results: A total of 50 cases were analyzed. The most common primary sign was focal abnormal T2 high signal intensity of the ACL. The most common secondary sign was anterior tibial translation of tibia >7mm. Conclusion: It was concluded that the diagnosis of ACL tear can be made on the basis of primary signs alone, but the secondary signs corroborates the diagnosis. The anterior tibial translation and positive PCL line have higher sensitivity than other secondary signs.