Acromioclavicular septic arthritis: a case report of a novel pathogen.

In immunocompetent patients, septic arthritis of the acromioclavicular (AC) joint is a rare entity. It can be difficult to discern from glenohumeral septic arthritis and AC joint impingement syndrome. The usual symptoms are fever, erythema, swelling, palpable pain over the AC joint, and pain with shoulder motion.