Radiological Case of the Month

A 4-week-old female infant was seen in the emergency room because of swelling around the left shoulder and decreased movement and apparent pain with elevation of the left arm. The infant was afebrile, breast-feeding normally, and otherwise active. There had been no history of trauma or birth injury. No other areas of swelling were noted, nor was there any rash, pustules, or purpura. An anteroposterior roentgenogram of the thorax including the shoulders was obtained (Fig 1). Despite the absence of systemic symptoms, the roentgenographic appearance strongly suggested osteomyelitis and concomitant septic arthritis. On physical examination the findings were confined to the left arm and shoulder. There was marked swelling of the anterior and lateral aspect of the left shoulder. Tenderness was obvious on palpation of the left humeral head. The left arm was internally rotated and flexed slightly at the elbow.