The aim of this study is to evaluate the prevalence of synovitis in adult patients with haemophilia A.

The bleeding disorder haemophilia causes recurrent spontaneous bleedings primarily into the joints and soft tissues. The reason is a congenital lack of factor VIII (haemophilia A) or factor IX (haemophilia B). In Germany, the most affected joints are the ankle, knee, and elbow. The joint bleedings are accompanied by pain and an inflammatory process that leads to synovitis and ultimately to degenerative joint changes resulting in haemophilic arthropathy: The synovial tissue is responsible for removing blood residuals from the joint cavity. However, blood components, especially iron, induce several changes in the synovial tissue. The resulting synovitis leads to damage of cartilage, bone cysts, osteophytes, and joint effusions. Synovitis can even become a bleeding-independent process, especially after repeated bleeding. According to current knowledge, there is no option to prevent synovitis except for preventing bleedings.

In the aftermath of recurrent joint bleedings, various changes in the synovial tissue, the articular cartilage, and the subchondral bone and blood vessels are observed. These changes are accompanied by restricted joint mobility and musculoskeletal dysfunction. In addition to these peripheral structural changes, various studies show that the entire musculoskeletal system is also affected by recurrent joint bleedings, as it adapts to pain.

Improved therapy over the past decades has led to a reduction in major joint bleeding rates. For this reason, it is important to examine whether this has improved the average joint status and how often patients with haemophilia (PwH) are affected by synovitis at all. Sonography is the radiation-free method of choice for the initial determination of synovitis.

In addition to the structural consequences, joint bleedings also lead to pain and reduction in physical performance. When considering the overall process of degenerative joint changes of PwH, it becomes apparent that this also reduces daily mobility and muscle strength. To the best of our knowledge, the effects of the degree of synovitis on pain perception and physical performance have not been evaluated in previous studies.

For this reason, the prevalence of synovitis in PwH and the consequences in relation to the pain situation and physical performance will be investigated.

Inclusion Criteria:

• Participants (≥ 18 years old) suffering from moderate or severe haemophilia A, also with inhibitor or joint replacement
• Complete documentation of hemophilia severity, treatment history (past 12 months), and bleeding events (past 12 months), inhibitor status (at time of enrollment and in past medical history)
• Submitted written consent to participate in the study

Exclusion Criteria:

• Patients suffering from other bleeding disorders conflicting with the research question
• Patients in clinical studies with investigational drugs

Adult patients (≥ 18 years of age) suffering from moderate (FVIII 1-5 %) or severe (FVIII <1 %) haemophilia A.

The publication of anonymous patient data is not allowed by informed consent.