A painful foot in a young boy

A 12-year-old white boy presented to the emergency department with a history of recurrent painful left foot. In the past, he had noticed vague dull ache in his left hindfoot, which occasionally became painful on severe exertion. Analgesics and rest for a few days eased his pain during these acute episodes. A detailed history and physical examination of his left foot found mild swelling and tenderness over the dorsum of the foot and in the mid-tarsal region. He had the full range of movements in all the joints of his forefoot and mid-foot. Movement in his hindfoot was slightly restricted (figure).