Painful os acromiale presenting as septic shoulder.

The unfused acromial apophysis of an os acromiale typically is an undetected orthopedic anomaly with minimal symptoms. In some instances, however, pain and disability can result from motion between the unfused bone fragments. Trauma to the acromion can similarly displace the unfused os acromiale or can result in chronic symptoms of pain and swelling. In this article, we report the case of a young man who had a fractured os acromiale secondary to trauma and presented with the signs and symptoms of a septic glenohumeral joint.