Which test is specifically used to assess ACL integrity?

• A. Pivot shift test
• B. McMurray test
• C. Lachman's test
• D. Phalen test

Answer: (C)

The test that best assesses ACL integrity focuses on how the tibia moves forward relative to the femur when the knee is in a protected, mid-range of flexion. By positioning the knee about 20–30 degrees and stabilizing the femur while drawing the tibia anteriorly, you directly stress the ACL. If the ACL is intact, the tibia can’t move far and there’s a clear endpoint. If the ACL is torn, there’s a noticeable increase in anterior translation and the endpoint becomes soft or disappears because the ligament no longer restrains forward movement. This makes the Lachman test highly sensitive for ACL ruptures, particularly in acute injuries, and it’s less affected by hamstring guarding than the other anterior-pulling test.

Pivot shift mainly reveals rotary instability associated with ACL deficiency and is less reliable in some patients or settings. McMurray tests the menisci, not the ACL. Phalen test is for carpal tunnel syndrome in the wrist, far from the knee.