Which physical examination test is most appropriate to rule out an ACL tear?

• A. Front Drawer Test
• B. Lachman's Test
• C. Pivot Shift Test
• D. McMurray Test

Answer: (B)

Lachman's Test is considered the most appropriate examination to rule out an anterior cruciate ligament (ACL) tear due to its high sensitivity and specificity. This test directly assesses the integrity of the ACL by evaluating the anterior translation of the tibia in relation to the femur when the knee is flexed at approximately 20 to 30 degrees.

During the test, the clinician stabilizes the femur with one hand while pulling the tibia forward with the other hand. A significant forward movement of the tibia compared to the femur indicates potential injury to the ACL. The quality of the endpoint during this maneuver is also telling; the presence of a soft endpoint suggests a tear.

While other tests are utilized in assessing ACL injuries, they either do not have the same diagnostic reliability or target different structures. The Front Drawer Test also assesses anterior translation but is less effective at lower knee flexion angles. The Pivot Shift Test evaluates the dynamic stability of the knee and is more complex and dependent on overall knee control. The McMurray Test, primarily used to evaluate meniscal tears, does not assess the integrity of the ACL directly at all.

Thus, Lachman's Test provides a quick, reliable assessment of ACL status and is widely used in clinical practice