Which test assesses posterior cruciate ligament laxity by evaluating posterior tibial sag?

Which test assesses posterior cruciate ligament laxity by evaluating posterior tibial sag?

• A. Posterior Drawer
• B. Lachman
• C. Pivot Shift
• D. Posterior Sag

Answer: (D)

Posterior tibial sag tests PCL laxity by using gravity to reveal a backward drop of the shin when the knee is flexed ~90 degrees with the patient lying supine. The PCL normally limits posterior movement of the tibia, so if it’s lax or torn, the tibia sags backward under the leg’s own weight, producing a noticeable posterior sag. This gravity-driven observation is what distinguishes the sag test from other PCL assessments that rely on an examiner’s force. For example, the posterior drawer test also checks PCL integrity but uses a manual posterior force to translate the tibia, while Lachman and Pivot Shift are primarily tests for ACL stability. So the test that specifically assesses posterior tibial sag is the Posterior Sag test.

Posterior tibial sag tests PCL laxity by using gravity to reveal a backward drop of the shin when the knee is flexed ~90 degrees with the patient lying supine. The PCL normally limits posterior movement of the tibia, so if it’s lax or torn, the tibia sags backward under the leg’s own weight, producing a noticeable posterior sag. This gravity-driven observation is what distinguishes the sag test from other PCL assessments that rely on an examiner’s force. For example, the posterior drawer test also checks PCL integrity but uses a manual posterior force to translate the tibia, while Lachman and Pivot Shift are primarily tests for ACL stability. So the test that specifically assesses posterior tibial sag is the Posterior Sag test.