Lachman maneuver is used to detect?

• A. Posterior cruciate ligament laxity
• B. Medial collateral ligament sprain
• C. Ankle instability
• D. Anterior cruciate ligament instability

Answer: (D)

The Lachman maneuver assesses the anterior cruciate ligament by evaluating how far the tibia can translate forward relative to the femur when the knee is flexed about 20–30 degrees. The ACL normally prevents this forward movement and provides rotational stability. If the ACL is torn or lax, the tibia moves forward more easily and the end feel is soft or indistinct, giving a positive sign. This test is especially reliable because placing the knee in modest flexion reduces hamstring guarding, improving sensitivity compared with the straight-backward (anterior drawer) test in acute injuries. So, the maneuver specifically detects ACL instability. It would not assess posterior cruciate ligament laxity (that’s the posterior drawer test), medial collateral ligament sprain (valgus stress testing), or ankle instability (requires ankle-focused maneuvers).