What injury mechanism is described as a valgus force with the foot planted in slight external rotation?

The injury mechanism described as a valgus force with the foot planted in slight external rotation is associated with the Unhappy Triad, which involves a combination of injuries to the anterior cruciate ligament (ACL), medial collateral ligament (MCL), and meniscus. This specific mechanism typically occurs during activities such as cutting or twisting, where excessive stress is applied to the knee while the foot remains firmly planted on the ground.

When the knee experiences a valgus force, it is pushed inward while the foot is turned slightly outward, creating a strain on the connecting ligaments and cartilage in the knee joint. This combination of forces can lead to the simultaneous injury of multiple structures, which is characteristic of the Unhappy Triad.

Understanding this mechanism is essential for recognizing the nature of injuries in athletes and guiding appropriate treatment and rehabilitation strategies. The other options, while they may involve knee injuries, do not specifically correlate with the combination of forces described in the question.