<prompt> An 18-month-old boy slipped and hurt his right knee while walking. He presents with a tender, swollen, warm knee with significant hemarthrosis. His PT is 12 normal, 13 seconds, PTT is over 100 normal, 25 seconds, platelet count is 300,000mm3, and bleeding time is normal. Initial management should consist of which of the following?Fresh-frozen plasmaAspiration of kneeFactor VIII concentratePassive exercise  <response>: The boy has hemophilia. Management consists of infusion of factor VIII concentrate. Bed rest and local cold packs are helpful. Aspiration of the knee to remove blood and passive exercise are not recommended for fear of recurrent bleeding. In contrast, active exercise is beneficial because movement beyond the point when bleeding can recur is limited owing to pain. Fresh-frozen plasma has a low level of factor VIII 0.6 UmL and is not useful because the required volume is excessive. Patients can use long leg splint. 