Synovial Proliferation on Routine Ultrasound: Active or Inactive?

Inclusion Criteria: * Gender: male * Patients with severe haemophilia A or B * Treated with registered prophylaxis medication including coagulation factors and by- passing agents. * Age ≥ 12 years * Subclinical synovial proliferation in ≥1 joint (ankle, knee and/or elbow), defined as the presence of hypertrophic synovium, score \>0 according to the HEAD-US protocol, as confirmed during routine ultrasound screening. * Able to give written informed consent. Exclusion Criteria: * A major bleed ≤ 3 months or a minor bleed ≤ 1 month prior to inclusion in the joint of interest. * On demand therapy. * Currently treated with any type of haemophilia prophylaxis medication. * Joints with prosthesis or treated with arthrodesis will not be included for physical examination and ultrasound analysis. However, participants may still be included in the study with their other joints. * Confirmed inflammatory joint diseases such as rheumatoid arthritis or psoriatic arthritis. * History of inhibitor development (≥ 5 Bethesda Units\* (BU) at any time or 1-5 BU for * 1 year prior to inclusion. * Contra-indication for treatment with NSAIDs, (allergy, severe liver failure, renal failure (GFR \<30ml/min), congestive heart failure (NYHA II-IV), peripheral arterial disease and/or cerebrovascular disease.