The anterolateral ligament in acute knee trauma: patterns of injury on MR imaging

To delineate the spectrum of traumatic knee injuries associated with injury of the anterolateral ligament of the knee (ALL).

A retrospective review of 200 MRI scans undertaken for acute knee trauma was performed. In each scan, the ALL was scored as normal, sprained or torn. The menisci, ligaments and tendons of each knee were also assessed.

The mean age was 27.4 years (range, 9-69 years), and 71.5% (n = 143) of the patients were male. The anterolateral ligament (ALL) was graded as ruptured in 17 cases (8.5%), sprained in 58 cases (29%), normal in 116 cases (58%) and not visible in 9 cases (4.5%). Of cases with injury of the ALL (n = 75), there was associated injury of the anterior cruciate ligament (ACL) in 61 cases, medial collateral ligament (MCL) in 51 cases, popliteofibular ligament (PFL) in 29 cases, medial meniscus in 29 cases, lateral meniscus in 24 cases, lateral collateral ligament in 9 cases, posterior cruciate ligament in 8 cases, biceps femoris in 5 cases, popliteus tendon in 4 cases and fluid or oedema was seen adjacent to the iliotibial band in 59 cases. No cases of isolated ALL injury were seen.

ALL injury is not uncommon in acute knee trauma and is typically associated with significant internal derangement of the knee, especially anterior cruciate ligament rupture, ITB sprain, medial collateral ligament injury, meniscal tears and injury to the popliteofibular ligament.