From the Research
No, the Anterior Cruciate Ligament (ACL) cannot be torn during a properly performed Lachman test. The Lachman test is a diagnostic examination specifically designed to assess the integrity of an already potentially injured ACL, not to cause injury. During this test, the examiner stabilizes the femur with one hand while pulling the tibia forward with the other hand, with the knee flexed at approximately 20-30 degrees. The amount of anterior tibial translation and the quality of the endpoint are evaluated. The test uses gentle to moderate force that is well below the threshold needed to rupture a healthy ACL. A competent clinician applies only enough force to assess ligament laxity without risking further injury.
The most recent and highest quality study on this topic is from 2016 1, which developed a clinical decision support system to help clinicians plan ACL reconstruction procedures. Although this study does not directly address the risk of ACL injury during the Lachman test, it highlights the importance of proper technique and patient-specific considerations in ACL assessment.
Other studies, such as those from 2004 2 and 2012 3, have investigated the mechanics of the Lachman test and the contribution of each ACL bundle to the test. These studies provide valuable insights into the anatomy and biomechanics of the ACL, but they do not suggest that the Lachman test itself can cause ACL injury.
In fact, the Lachman test is considered safer than the anterior drawer test because the hamstring muscles are more relaxed at this angle of knee flexion, allowing for better assessment. If a patient experiences significant pain during the Lachman test, the examiner should immediately stop to prevent any potential aggravation of existing injuries.
Overall, the evidence suggests that a properly performed Lachman test is a safe and effective way to assess ACL integrity, and it is not likely to cause ACL injury. The key to safe and effective Lachman testing is proper technique and careful consideration of patient-specific factors.