Pyarthrosis complicating rheumatoid arthritis. Roentgenographic evaluation of 5 patients and review of the literature.

Five patients with pyarthrosis complicating rheumatoid arthritis are described. Only minimal clinical signs may be seen in such patients, making accurate diagnosis of this occasional complication difficult. Roentgenographic abnormalities include a rapidly enlarging joint effusion and progressive cartilage and bone destruction. Fistulas may develop. The principal differential diagnoses include exacerbtion of rheumatoid arthritis and alterations in the rheumatoid joint following trauma.