MRI evaluation of anterolateral ligament tears in knee injury with anterior cruciate ligament rupture

Abstract

Introduction: To evaluate the incidence of anterolateral ligament (ALL) tear in acute knee injury and its association with anterior cruciate ligament tear (ACL). Methods: Forty patients with isolated early ACL tears were prospectively reviewed under 3T-MRI evaluation to identify ALL tears. This was correlated with trauma mechanisms and degree of knee instability. Patients less than 18, or more than 50 years of age, and those with posterolateral corner injury or LCL instability were excluded, which left 31 patients (30 males: 1 female; mean age: 28.6 years) for the final evaluation. Results: The ALL was visualized completely on the MRI in all 31 patients. ALL had mid substance tear in 19 knees (61.3%), proximal femoral attachment in eight knees (25.8%), at the tibial end in 6 knees (19.3%) and was seen torn at both proximal and distal ends in five knees (16.1%). Clinical correlation revealed higher number of giving way episodes, more functional loss of activities and higher grades of pivot shift test in cases with ALL tear along with ACL tear as compared with patients who had ACL deficiency without concomitant ALL tear (p value <0.05). Conclusion: The ALL can be identified in all cases with 3T-MRI. Tears are clearly seen and may be classified according to location. We found no correlation of ALL tears with injury mechanism; however ACL deficient knees with concomitant ALL tear on MRI had more functional impairment and instability. Level of evidence: II b.