Native join septic arthritis.

species are associated with normal skin flora and cultures may be dismissed as contaminants. They are increasingly recognized as a cause of septic arthritis following shoulder arthroplasty and arthrotomy. We identified three cases of septic arthritis in native joints mimicking atypical osteoarthritis and review the literature, clinical course, and treatment of 18 cases. Two cases of acne in native knee joints and one in a sternoclavicular joint are described. A literature search for septic arthritis was performed. Clinical course, treatment, and outcome are reviewed for all cases. Our three cases were combined with 15 cases from the literature. Fourteen cases showed few signs of acute infection, slow culture growth, and delayed diagnosis. In 3 cases an early culture was dismissed as a contaminant. Six cases were reported as caused by recent arthrocentesis. Fifteen cases were cured with antibiotics, although 5 of these 15 also required surgical intervention. Two patients were diagnosed while undergoing surgery for osteoarthritis. Four patients required arthroplasty and two of our patients will require arthroplasty for good functional results. as a cause of septic arthritis in native joints demonstrates few signs of acute infection, presents with prolonged course, and is often misdiagnosed or unsuspected. Anaerobic growth may be delayed or missed altogether, and outcomes are consequently poor. Consider septic arthritis in atypical osteoarthritis prior to arthroplasty.