A clinician suspects a lateral collateral ligament injury. Which test is most appropriate to assess LCL integrity?

A clinician suspects a lateral collateral ligament injury. Which test is most appropriate to assess LCL integrity?

• A. Valgus stress test
• B. Posterior drawer test
• C. Varus stress test
• D. McMurray's test

Answer: (C)

The key idea is using targeted stress to distinguish which ligament is injured. The lateral collateral ligament resists a varus (inward) force at the knee, so testing with a varus stress directly challenges the LCL. When you apply a controlled varus force while stabilizing the thigh, a healthy knee should show little to no opening on the lateral joint line and symmetry with the other knee. If the LCL is damaged, you’ll see increased lateral gapping or pinpoint tenderness on the outer aspect of the knee. In contrast, a valgus stress test stresses the medial collateral ligament, a posterior drawer test evaluates the posterior cruciate ligament, and McMurray's test checks for meniscal tears. Therefore, for assessing LCL integrity, the varus stress test is the most appropriate.

The key idea is using targeted stress to distinguish which ligament is injured. The lateral collateral ligament resists a varus (inward) force at the knee, so testing with a varus stress directly challenges the LCL. When you apply a controlled varus force while stabilizing the thigh, a healthy knee should show little to no opening on the lateral joint line and symmetry with the other knee. If the LCL is damaged, you’ll see increased lateral gapping or pinpoint tenderness on the outer aspect of the knee.

In contrast, a valgus stress test stresses the medial collateral ligament, a posterior drawer test evaluates the posterior cruciate ligament, and McMurray's test checks for meniscal tears. Therefore, for assessing LCL integrity, the varus stress test is the most appropriate.