Abduction stress test assesses injury to which ligament?

• A. Medial collateral ligament
• B. Anterior cruciate ligament
• C. Lateral collateral ligament
• D. Posterior cruciate ligament

Answer: (A)

Abduction (valgus) stress test targets the medial collateral ligament because this ligament resists forces that push the knee outward toward the midline. When a valgus force is applied at the knee, the medial side is stressed; if the MCL is injured, you’ll see increased medial joint laxity or medial-sided pain. The test is often done with the knee slightly flexed to emphasize the MCL, though at full extension it may involve other structures as well. This maneuver doesn’t primarily test the lateral collateral ligament or the cruciate ligaments—the LCL is stressed with varus (adduction) forces, and ACL/PCL are better evaluated with tests like the Lachman or drawer maneuvers.