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

Abstract and Introduction


Septic arthritis is a dangerous medical condition associated with significant morbidity and mortality. However, the differential diagnosis can be broad with conditions that mimic this disease and require different evaluation and treatment. This narrative review presents the emergency medicine evaluation and management, as well as important medical conditions that may mimic this disease. Septic arthritis commonly presents with monoarticular joint pain with erythema, warmth, swelling, and pain on palpation and movement. Fever is present in many patients, though most are low grade. Blood testing and imaging may assist with the diagnosis, but the gold standard is joint aspiration. Management includes intravenous antibiotics and orthopedic surgery consult for operative management vs. serial aspirations. Clinicians should consider mimics, such as abscess, avascular necrosis, cellulitis, crystal-induced arthropathies, Lyme disease, malignancy, osteomyelitis, reactive arthritis, rheumatoid arthritis, and transient synovitis. While monoarticular arthritis can be due to septic arthritis, other medical and surgical conditions present similarly and require different management. It is essential for the emergency clinician to be aware how to diagnose and treat these mimics.


Monoarticular arthritis is a common presentation to the emergency department (ED) and major cause of disability in the United States. Monoarticular arthritis has a wide range of potential etiologies, ranging from benign to life-threatening. One of the most concerning causes in a patient with monoarticular arthritis is septic arthritis. The prevalence of septic arthritis among ED patients with monoarticular arthritis varies significantly between studies; however, an incidence of 4–60 cases per 100,000 population per year is suggested in the literature.[1–6] Based on the literature, higher rates of septic arthritis are present in immunocompromised patients and those with prosthetic joints, where disease incidence increases to 70 cases per 100,000 patients annually.[7–13] Septic arthritis possesses a bimodal incidence, with peaks in both childhood and adults over the age of 55 years.[4–9]

Septic arthritis consists of a bacterial infection of the joint space that is associated with rapid joint destruction within days if not adequately treated. Mortality rates can be significant, ranging from 3–25%.[3,5–7] Despite the severity of illness, septic arthritis may be subtle, with many patients lacking the classic signs, symptoms, or laboratory findings.[8–10] There are also a large number of conditions that may mimic septic arthritis, further confounding the diagnosis.