Pediatric musculoskeletal disorders Quiz: Ace Your Exams

A 7-year-old boy is brought to the pediatrician’s office for evaluation of left hip pain. The patient’s parent noticed a left-sided limp several weeks ago and initially attributed it to a fall at the playground. The pain has persisted and is minimally relieved with rest or ibuprofen. The patient has no significant past medical history. He takes no daily medications, and immunizations are up to date. Temperature is 37°C (98.6°F), pulse is 82/min, and blood pressure is 116/72 mm Hg. The child is in the 50th percentile for height and 40th percentile for weight. Examination shows a well-appearing and cooperative child. With internal rotation and abduction of the left hip, range of motion is limited secondary to pain. The remainder of the examination is noncontributory. An X-ray of the patient's hip is demonstrated below. Which of the following is the most likely diagnosis?
  
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