Clinical History.—The patient is a 12-year-old boy who has pain and swelling of the left knee.
When he was 4 days old, a circumcision was done, and bleeding persisted for 17 days following the procedure. Transfusion was not required. At 6 months of age there was spontaneous swelling of the left knee. During the intervening years, there has been swelling of various joint areas, with particular involvement of the left knee.
There are two older sisters who are normal, and there is no family history of bleeding tendencies.
Physical Examination.—The temperature reading was 36.8 C, the height 152 cm, and weight 43 kg. He was a well-developed, well-nourished boy, using crutches to walk. Results of examination of the eyes, ears, nose, mouth, and neck were normal. The chest was clear to auscultation and percussion. The cardiac rhythm was normal, and no murmurs were heard. No organomegaly or tenderness