Which of the following is NOT an ACL stability test?

• A. Lachman's
• B. Anterior Drawer
• C. Pivot Shift
• D. Posterior Drawer

Answer: (D)

ACL stability involves assessing how the tibia moves forward relative to the femur and how the knee behaves under rotational stress. The Lachman test uses a small degree of knee flexion (about 20–30 degrees) to place the ACL under tension while the femur is stabilized; an excessive anterior movement or a soft endpoint indicates ACL deficiency. The Anterior Drawer test, performed with the knee bent to about 90 degrees, also stresses the ACL by attempting to translate the tibia anteriorly; exaggerated forward glide suggests ACL injury. The Pivot Shift test reproduces a combination of anterior and rotational instability by applying valgus stress and internal rotation, producing a clunk and apprehension when the ACL is torn. In contrast, the Posterior Drawer applies a posterior force to the tibia to assess the PCL; a positive result indicates PCL injury, not ACL instability. Therefore, posterior drawer is not an ACL stability test.