During a valgus stress test, increased laxity in the knee suggests which ligament may be injured?

Increased laxity observed during a valgus stress test indicates a potential injury to the medial collateral ligament (MCL). This test involves applying a lateral force to the knee while stabilizing the leg, creating an environment where the MCL is under stress. If the MCL is intact, the knee should remain stable. However, increased laxity during this stress suggests that the MCL is compromised, which aligns with mechanisms of injury commonly seen in sports-related activities.

The MCL is primarily responsible for resisting forces that push the knee medially, so when evaluating the joint under a valgus load, that is precisely where one would assess for stability. This understanding is crucial for diagnosing knee injuries and planning appropriate management and rehabilitation strategies.