Loan T. Kline, MD

THE CASE: A 7-year-old boy has had left ankle pain for 2 days. Neither he nor his mother can recall any recent trauma to the joint. He is usually very active, but he has been unable to bear weight on the left foot and has been resting in bed. His mother reports that he had some tactile fevers, which were transiently relieved with ibuprofen, and that he has been eating and drinking normally. Despite the application of ice and elevation, the ankle has become red and swollen.