A 2-year-old girl with a limp

A 2-year-old girl with no past medical history was transferred from another hospital to our tertiary care medical center for evaluation of a limp. She had been healthy until a month prior, when she was noted to be limping on her right leg. This problem progressed, and she refused to walk 3 weeks later. Her mother recalled that the child fell while walking about a week before the symptoms started. The child had a mild fever for 2 days during the illness. There was no history of upper airway illness, cough, diarrhea, skin rash, sick contacts, travel, or animal exposure. Her past medical history was unremarkable. She was healthy, up-to-date with immunizations, lived with both parents and two siblings in Chicago, and did not attend day care.