A 28-year-old footballer suffers a valgus stress injury to the knee. Examination reveals excessive lateral displacement of the tibia on the femur and a positive Lachman test. Which structure is primarily damaged?
- A Posterior cruciate ligament
- B Medial collateral ligament
- C Anterior cruciate ligament ✓
- D Lateral collateral ligament
Correct answer: C. Anterior cruciate ligament
Explanation
The anterior cruciate ligament (ACL) prevents anterior translation of the tibia on the femur and resists internal tibial rotation. The Lachman test (anterior drawer with the knee at 20-30° flexion) is the most sensitive clinical test for ACL rupture. A valgus stress combined with sudden deceleration or pivoting is the classic mechanism for ACL injury in athletes.
Reference: BD Chaurasia's Human Anatomy, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.