The limping child.

A child who limps often presents a diagnostic challenge. The differential diagnosis is extensive. Although the most common cause is trauma, awareness of other potential causes is important. The age of the child and the pattern of the gait help narrow the differential diagnosis. In most cases, a diagnosis can be made from the history and physical examination. If the diagnosis is not obvious after a careful clinical evaluation, plain radiographs provide an excellent means of screening for fracture, joint effusion, lytic lesions, periosteal reaction, and avascular necrosis. Other tests should only be ordered when indicated.