Snapshot A 20-year-old man presents to the emergency department with severe knee pain. He reports that he was playing rugby during practice for his college team. While playing he was struck in his lateral knee and he had to be carried off of the playing field. On physical exam, the physician notes a positive anterior drawer test, a positive McMurray test, and increased laxity with valgus stress. Introduction Clinical definition a knee injury that results in damage to the medial collateral ligament (MCL) login to view 1 more bullet anterior cruciate ligament (ACL) medial meniscus login to view 1 more bullet Epidemiology incidence more common in people who engage in contact sports (e.g., football and rugby) Etiology a blow to the lateral knee Presentation Symptoms knee pain stiffness and swelling locking or catching of the knee knee instability Treatment Operative orthopedic surgery indication login to view 1 more bullet