&Hemarthrosis=Hemarthrosis is a bleeding into joint spaces. It usually follows injury but occurs mainly in patients with a predisposition to hemorrhage such as those being treated with warfarin (or other anticoagulants) and patients suffering from hemophilia. It can be associated with knee joint arthroplasty. In hemophilia it may occur spontaneously, and recurrent hemarthroses are a major cause of disability in that patient group due to hemophilic arthropathy, requiring synovectomy, joint replacement and increased medical therapy to prevent further bleeding episodes, although it is controversial whether clotting factor administration adequately prevents hemarthroses.