POCUS: Hemostatic Potential and Joint Health in Patients With Severe Hemophilia A on Novel Replacement Therapies

This is a research study to find out if there is a difference in the way children with hemophilia A form a clot and also evaluate if they develop tiny bleeds within the joint and subsequently early joint changes when receiving extended half-life factor VIII based replacement therapy vs non-FVIII based replacement as part of their hemophilia treatment to prevent spontaneous joint bleeds. Both therapies are standard of care therapies for patients with hemophilia A. The only experimental/research procedures as part of this study include the thrombin generation assay and ultrasound. All other procedures are standard of care.