Anterior cruciate ligament injury

A 24-year old man presents to the emergency department after injuring his right knee during a pick-up basketball game. The patient was running and dribbling toward the basket when he suddenly changed direction and felt a “pop” in the knee. The patient subsequently had intense pain, significant swelling of his knee, and felt like his knee would “give out” on him when ambulating. Currently he is able to bear weight without pain but still feels unsteady when ambulating. Physical examination is notable for a small right knee effusion. There is full range of motion of the knee without locking or clicking. Which of the following physical examination maneuvers is most likely to aid in diagnosing this patient’s clinical condition?