What is the most critical diagnosis to consider in the patient with monoarticular symptoms?
Joint infection, which represents a rheumatologic emergency, is the most critical diagnosis to consider and must be diagnosed quickly and managed aggressively. Bacterial infections, especially those due to gram-positive organisms, can destroy the joint cartilage within a few days. Prompt and proper treatment of the septic joint will usually leave it without permanent structural damage. Additionally, as the septic joint is usually the result of hematogenous spread of infection from another body site, early recognition of the joint process allows more timely diagnosis and treatment of the primary infection. When evaluating a patient with acute monoarticular arthritis, a good rule of thumb is to assume that the joint is infected until proven otherwise (“aspirate, or litigate!”).