Anterolateral ligament injuries in knees with an anterior cruciate ligament tear: Contribution of ultrasonography and MRI.

OBJECTIVES

To describe the pathological appearance of the anterolateral ligament (ALL) on US and MRI in knees with an anterior cruciate ligament (ACL) tear.

METHODS

This prospective study included 30 patients who had a suspected acute ACL tear. Their injured and contralateral knees were evaluated with radiography, US and MRI. Two radiologists evaluated the ALL on the MRI and US examinations. Agreement between these examiners' findings was evaluated with Cohen's kappa.

RESULTS

On US examination, the ALL was found to be injured in 63% of cases (19/30; k = 0.93). The enthesis was found to be torn in 50% of cases (15/30; k = 1), with the tear located at the tibial attachment in all instances. On the MRI exam, the ALL was found to be injured in 53% of cases (16/30; k = 0.93). The enthesis was found to be torn in 13% of cases (4/30; k = 0.76), with the tear located at the tibial attachment in all instances (k = 0.93).

CONCLUSION

ALL injuries that occur with ACL tears are located at the tibial enthesis. They are often associated with bone avulsion at the enthesis and are better viewed on US.

KEY POINTS: • ALL injuries often occur in combination with ACL tears. • ALL injuries can be assessed with ultrasonography and MRI. • ALL injuries associated with ACL tears are located at the tibial enthesis.