Evaluation and Management of Septic Arthritis and Its Mimics in the Emergency Department

Brit Long, MD; Alex Koyfman, MD; Michael Gottlieb, MD


Western J Emerg Med. 2019;20(2):331-341. 

In This Article


Septic arthritis is a potentially deadly condition that unfortunately does not always present classically. The red, hot, swollen joint mandates consideration of septic arthritis. No physical examination finding can rule out the condition, and serum blood tests should not be used to exclude septic arthritis. Diagnostic aspiration is required, with the sample sent for synovial WBC, Gram stain, culture, and lactate. Synovial lactate and culture are the best laboratory tests, as some patients can present with normal synovial WBC and Gram stain. Management requires orthopedic surgery consultation and antibiotics. There are a significant number of mimics of septic arthritis, including abscess, cellulitis, gout, rheumatoid arthritis, osteomyelitis, malignancy, Lyme disease, and avascular necrosis. A focused history and examination, along with dedicated diagnostic evaluation, can assist in differentiating these conditions.