Review Question - QID 214940

An 18-year-old man presents for evaluation of left leg pain. He states that he was tackled during a football game last week and suffered an abrasion to his left shin. Since then, he has developed progressive left shin pain unresponsive to ibuprofen and now has difficulty bearing weight on the left leg. He also reports a subjective fever over the last 2 days. He has a history of sickle cell disease and has required blood transfusions intermittently since childhood. His only medication is hydroxyurea. His temperature is 101.3°F (38.5°C), blood pressure is 123/75 mmHg, pulse is 98/min, and respirations are 15/min. Physical exam is notable for a healing abrasion and tenderness, warmth, and erythema on the left anterior shin. A radiograph of the left lower extremity shown in Figure A. Which of the following is the most likely diagnosis?