The acutely swollen joint. First impressions may mislead.

An acutely swollen joint may be indicative of a number of disease entities. A thorough history and physical examination are the cornerstones of evaluation. Laboratory findings can be useful in diagnosis, as can response to therapy (eg, response to penicillin in gonococcal arthritis is often the only criterion for diagnosis, as the organism is difficult to culture). Patients with malignancy (especially leukemia) or who are immunosuppressed or otherwise debilitated are at particular risk for a septic cause of swelling. Infectious arthritis should be the first potential cause looked for in these patients as well as in patients with such preexisting joint diseases as rheumatoid arthritis. The diagnosis of joint sepsis is confirmed by examination of aspirated joint fluid. In no case should a swollen joint be injected with corticosteroids until all possibility of infection has been eliminated.