Individualized Prophylaxis for Severe Hemophilia A Children

Inclusion Criteria: 1. Severe hemophilia A with FVIII \<1 % 2. Age from 6 to 10 years 3. Patients with more than 50 exposure day (ED) 4. Patients with one or more target joints (a target joint is defined as a joint with 3 or more bleeds in a consecutive 3 months) or disease joints (defined as presence of visible joint swelling and /or limitation of movements and/or joint deformities in the absent of an acute joint bleed ) 5. on-demand treatment more than 12months before the study Exclusion Criteria: 1. A history of FVIII inhibitor (titer greater than 0.6 BU) and detectable FVIII inhibitor at screening (titer greater than 0.6 BU) 2. Chronic renal failure (serum creatinine greater than 2.0 mg /dL) 3. Chronic Liver disease (ALT greater than 200 U/L)) 4. Patients with clinically documented immunodeficiencies 5. Patients anticipated to require Major surgery 6. Patients with competing high risks such as symptomatic HIV infection, Juvenile rheumatoid arthritis, metabolic bone diseases, or other diseases known to mimic or cause joint diseases 7. Patients live too far from the comprehensive care centre at BCH and had demonstrated previous non compliance to therapies or clinical studies