Bleeding into a joint, causing the capsule that encloses the joint to swell, therefore causing stiffness and pain.
Haemarthrosis is often the result of severe injury to the joint, such as a torn ligament, torn capsule, or fracture of a bone forming part of the joint. Generally the cause is a sports injury to the knee.
More rarely the causes are bleeding disorders, such as haemophilia (in which failure of the blood-clotting mechanism creates abnormal bleeding). Any joint can be affected and bleeding into the joint can occur impulsively or be caused by even a minor knock. Excessive amounts of anticoagulant drugs can also create haemarthrosis.
Repeated haemarthrosis can injure joint surfaces, causing osteoarthritis.
Symptoms and signs
Haemarthrosis causes a joint to swell straightaway after injury. The joint can slowly stiffen into a fixed position as a result of spasm in the surrounding muscles.
Ice-packs can bring down the pain and swelling. Fluid can be taken from the joint in order to relieve pain and for diagnosis.
Haemophiliacs are given factor VIII to encourage blood clotting. Resting the joint in an elevated position can help stop further bleeding.