Septic Arthritis of the Elbow in Children: the Role of Sonography

Twelve children with suspected septic arthritis of the elbow were prospectively studied with plain-film radiography and ultrasound. Imaging data were correlated with clinical history and final diagnosis. Joint effusion was seen by sonography in six patients, four of whom underwent ultrasound-guided joint aspiration, confirming the diagnosis of septic arthritis in two patients and excluding it in two. Of nine patients whose plain films showed only soft tissue swelling, seven had one or more significant findings with sonography: joint effusion (without fat pad elevation on lateral plain films) in three patients, periosteal reaction in two, and epitrochlear mass in three. Sonography confirmed soft tissue swelling alone in two patients, thus excluding the diagnosis of septic arthritis and obviating unnecessary attempts at joint aspiration. Sonography of the elbow is an informative, easily performed examination, which is capable of showing both intra- and extra-articular abnormalities not apparent by plain radiography. Both the demonstration of pathologic changes and the failure to show joint fluid may affect clinical management.