Differentiating pyogenic arthritis from spontaneous hemarthrosis in patients with hemophilia.

Pyogenic arthritis in patients with hemophilia is predominantly monoarticular, usually involving the knee, is associated with hemophilic arthropathy and other predisposing factors for infection, is mainly due to Staphylococcus aureus and carries serious morbidity. In patients with hemophilia, it is associated significantly with fever, an increased leukocyte count, knee joint involvement and possible predisposing factors for infection. Such patients presenting with unexplained fever of more than 1 degrees C(1.8 degrees F) and acute symptoms of joint inflammation should have an arthrocentesis.