Diagnostic accuracy of ACL tears according to tear morphology.

This retrospective analysis of 182 consecutive patients who underwent anterior cruciate ligament (ACL) reconstruction aimed to assess the clinical examination under anaesthetic and the MRI diagnostic accuracy of arthroscopically-proven, complete ACL ruptures, depending on the morphology of the torn ligament. Patients were then assigned to Group 1 (ACL not reattached) or Group 2 (ACL re-attached abnormally). Of 104 patients (57.1%) in Group 2, 94 (51.7%) had an abnormal re-attachment of the torn ACL to the posterior cruciate ligament (PCL). There was no significant difference between the groups on MRI reporting of a complete ACL tear (p = 0.123) and pivot shift test. On Lachman testing, more patients in Group 1 had an increased laxity compared with Group 2 (p = 0.014); similarly, more patients in Group 1 had an absent endpoint compared with Group 2 (p = 0.008). An ACL-deficient knee with an abnormal re-attachment of the torn ligament appears to be more difficult to diagnose than if there has been no re-attachment.