Assessment of Anterolateral Complex Injuries by Magnetic Resonance Imaging in Patients With Acute Rupture of the Anterior Cruciate Ligament.

PURPOSE: To assess anterolateral complex (ALC) injuries in patients with acute anterior cruciate ligament (ACL) rupture on magnetic resonance imaging (MRI). METHODS: Patients with acute ACL rupture who underwent ACL surgery between 2015 and 2017 and underwent MRI within 6 weeks of the initial trauma were included. Two radiologists assessed magnetic resonance images retrospectively for the status of the ALC, including the iliotibial band (ITB), Kaplan fibers, and anterolateral ligament (ALL), as follows: grade 0, normal; grade 1, periligamentous edema; grade 2, partial tear; and grade 3, complete tear. The findings were analyzed using the Friedman test and weighted κ values. RESULTS: Sixty-nine MRI scans were reviewed. Of the 69 patients, 51% had associated injuries to the ITB (grade 1, n = 31; grade 2, n = 4), 33% had associated injuries to the Kaplan fibers (grade 1, n = 21; grade 2, n = 2), and 57% had associated injuries to the ALL (grade 1, n = 12; grade 2, n = 22; grade 3, n = 5). We found a significant difference in the frequency and grading between ITB, Kaplan fiber, and ALL injuries (P ≤ .032). Inter-reader agreement for assessing the ALC on MRI was almost perfect (κ ≥ 0.922). CONCLUSIONS: On the basis of MRI analysis, ALL injuries were found with varying degrees of severity and intensity with noted injuries to associated surrounding fibers in patients with acute ACL rupture. LEVEL OF EVIDENCE: Level IV, case series.