Imaging of Arthropathy in Boys With Hemophilia in China

Inclusion Criteria: * Hemophilia A with baseline FVIII levels of \<2% * Clinical history of ≥ 50 exposure days to FVIII prior to the study start. * On-demand treatment, prophylaxis FVIII infusions or treatment with plasma-derived products for \>3 months prior to enrollment into the study. Exclusion Criteria: * History of FVIII inhibitor (titer \>0.6 Bethesda Units \[BU\]) * Chronic renal failure (serum creatinine \>2.0 mg /dL). * Chronic liver disease (alanine aminotransferase \[ALT\] \>200 U/L). * Clinically documented immunodeficiency. * Anticipation of need for major surgery during the study period. * Association of diseases known to mimic or cause joint diseases such as symptomatic human immunodeficiency virus (HIV) infection, juvenile idiopathic arthritis, and metabolic bone diseases. * Social barriers for participation in the study such as long distance between home and the comprehensive care centre, and documented track record of non-compliance to therapies or participation in clinical studies. * Neuro-developmental/behavioral problems. * Contraindications to MR imaging (presence of heart pacemakers, metallic foreign bodies in the eye, aneurysm clips, severe claustrophobia).