Hemophilia is hereditary x-chromosomal recessive disorders. Hemophilia A is caused by deficiency or absence of coagulation factor VIII and hemophilia B is caused by that of coagu‐ lation factor IX. The prevalence is reported as one in 5000 in the male population and one in 10000 overall. These diseases are classified into three categories according to serum coagula‐ tion factor activity; severe ( 5%). The particular hemophilic manifestation is intra-articular bleeding. Intra-articular bleeding is usually occurred by trau‐ ma but also often spontaneously. Approximately 5% of first bleeding episodes in hemophilic boys are into a joint. The average age of first intra-articular bleeding is 1.91±0.91 years old and the median age of that is 1.63 years old [1]. A joint in which four or more recurrent bleedings have occurred in the prior 6 months is defined as target joint. In the United States, 2.3% of children 2-5 years of age enrolled in the Universal Data Collection Project have tar‐ get joints [2]. Most of target joints have hemophilic synovitis, which is characterized by in‐ flammation, angiogenesis and fibrosis [3] and develop hemophilic arthroplasty which is characterized by cartilage and bone destruction.