Sonographic detection, evaluation and aspiration of infected acromioclavicular joints

To describe the sonographic findings of septic arthritis of the acromioclavicular joint.

A retrospective study of five male patients was carried out. Four of the patients were referred because of signs and symptoms suggestive of glenohumeral joint septic arthritis, one for signs and symptoms suggestive of septic arthritis of the acromioclavicular joint. All the acromioclavicular joints were evaluated with ultrasound, aspirated and the aspirate cultured.

All patients had normal ultrasound findings of their glenohumeral joints and distended acromioclavicular joints as determined by ultrasound. Ultrasound examination elicited focal tenderness over the acromioclavicular joint. Aspirates of each acromioclavicular joint grew pyogenic organisms.

Infection in the acromioclavicular joint is uncommon, but is seen in increased frequency in immune-compromised patients and intravenous drug users. A normal glenohumeral joint on ultrasound in a patient suspected of having a septic shoulder should prompt careful review of the acromioclavicular joint. Aspiration of the acromioclavicular joint is easily performed under ultrasound guidance.