The anterior cruciate ligament (ACL) of the knee prevents which primary movement?

• A Posterior translation of the tibia on the femur
• B Valgus stress at the knee joint
• C Anterior translation of the tibia on the femur (positive anterior drawer test and Lachman test) ✓
• D Hyperextension of the knee joint

Explanation

The ACL attaches from the anterior intercondylar area of the tibia to the lateral condyle of the femur (posterior aspect). Its primary function is to resist anterior translation of the tibia relative to the femur and to limit internal rotation. ACL rupture produces a positive anterior drawer test (tibia pulled forward with knee at 90 degrees) and a positive Lachman test (more sensitive, knee at 30 degrees). The posterior cruciate ligament (PCL) prevents posterior tibial translation. The medial collateral ligament resists valgus stress.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

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Written and medically reviewed by the StethoPrep medical team.