Which structure is primarily assessed when testing knee stability?

• A. Medial collateral ligament
• B. Patellar tendon
• C. Quadriceps muscle
• D. Achilles tendon

Answer: (A)

The medial collateral ligament (MCL) is primarily assessed when testing knee stability because it plays a crucial role in maintaining the integrity of the knee joint during activities that involve lateral movement and weight bearing. The MCL provides stability against valgus stresses, which occur when there is a force applied to the outside of the knee that pushes the knee inward.

When clinicians perform physical assessments for knee stability, specific tests such as the valgus stress test focus on the integrity of the MCL. This test evaluates how the ligament responds to stress and helps identify injuries or tears. In contrast, while the patellar tendon, quadriceps muscle, and Achilles tendon are important for knee function and movement, they do not primarily govern knee stability in the same way that the MCL does. Each of these structures has its own roles in movement and mobility but doesn’t address the stress applied to the knee joint itself as directly as the MCL does.