Which clinical sign is most closely related to examining an ACL injury?

The Lachman Test is the most closely related clinical sign for examining an anterior cruciate ligament (ACL) injury. This test is specifically designed to assess the integrity of the ACL by evaluating the stability of the knee. During the Lachman Test, the examiner holds the femur in place and pulls the tibia forward, looking for increased anterior translation of the tibia compared to the femur. A significant amount of forward translation suggests a tear of the ACL.

In contrast, other tests like the McMurray Sign primarily assess for meniscal injuries rather than directly for ACL integrity. The Posterior Drawer Sign evaluates posterior instability and is more indicative of a posterior cruciate ligament (PCL) injury. Joint line tenderness can occur due to various knee pathologies, including meniscal tears, and is not specific to ACL injuries. Therefore, the Lachman Test stands out as the most reliable and focused assessment for an ACL injury.