Hemophilia causes repetitive bleeding episodes throughout the musculoskeletal system, primarily into joints, such as knees and ankles. This leads to significant joint damage resulting in increased pain reproduction, decreased functional abilities, such as walking, and negatively impacts quality of life. Traditionally the extend of joint damage has been examined via clinical assessments, such as the Hemophilia Joint Health Scores, x-rays, MRIs, and more recently musculoskeletal ultrasound (MSKUS). However, these modalities fail to establish the global impact of joint damage on the entire body of a person with hemophilia and their functional abilities. Analyzing joint motion and forces acting upon the joint during walking has been a widely established technique to gain understanding of abnormal three-dimensional movements and is a key factor in clinical decision making-processes. With the overall goal of establishing better treatment approaches for persons with hemophilia it is vital to understand the underlying functional joint limitations. Therefore, the purpose of this study is to investigate characteristics of damaged joints, joint motion and control as well as forces acting upon the joint during walking in persons with hemophilia.