<prompt> A 22-year-old male basketball player presents with a swollen, painful left knee. He was on a fast break and as he began to jump for an alley-oop, he felt his knee give out and he collapsed to the floor. What is the most likely diagnosisPatello-femoral dislocationAnterior cruciate ligament injuryMedial collateral ligament injuryPosterior cruciate ligament injury  <response>: The history provided describes a noncontact injury to the knee during an acceleration-decelerationpivoting move with the patient experiencing a feeling of giving way in his knee. The player quickly accumulates a knee effusion and has significant pain. These findings are characteristic descriptions of an ACL injury. The Lachman test is diagnostic for this injury, and an MRI would confirm the diagnosis. 