Review Question - QID 215631

A 17-year-old, skeletally mature, high school pitcher presents to your clinic with complaints of right elbow pain. He is a right-hand dominant starting pitcher. He notes that early in the season one of the team’s starting pitchers sustained a season-ending injury, so he and the other starting pitchers were forced into a more rigorous pitching rotation with less rest and more innings pitched. He reports that he was having difficulty maintaining velocity and control of his fastball and notes that his pain was most pronounced during the end of his wind-up. On physical examination, he has mild paraesthesias in the ulnar nerve distribution, and his pain is reproduced when a valgus forced is applied to his elbow during active flexion. He has painless active motion of his wrist. What is the most likely diagnosis for this patient?