Hemophilic arthropathy refers to permanent joint disease occurring in hemophilia sufferers as a long-term consequence of repeated hemarthrosis (bleeding into joints). Around 50% of patients with hemophilia will develop a severe arthropathy.
Hemarthrosis often begins in early childhood soon after the child starts to walk. A single hemarthrosis may give rise to low-grade inflammation of the joint lining or synovium (a condition called synovitis), which predisposes the “target” joint to recurrent hemarthrosis. This initiates a cycle of chronic synovitis, inflammatory arthritis and progressive joint surface destruction.
Hemophilic synovitis demonstrates inflammatory changes with elements similar to rheumatoid arthritis and pigmented villonodular synovitis, joint diseases characterized by overgrowth of the synovial membrane. The thickened and overactive membrane secretes chondrolytic enzymes, chemicals produced by the synovial cells that break down joint cartilage and erode the joint surface. The thickened membrane also destroys the joint surface and adjacent bone by direct invasion. Blood vessels in the thickened membrane then become enlarged.
With each hemarthrosis, the synovium becomes thicker as a result of blood breakdown products that overwhelm the membrane’s ability to take it in. The natural history of hemophilic synovitis is progression to end stage arthropathy and arthrofibrosis.
The joints most commonly affected by hemophilic arthropathy are knees, elbows and ankles. Hips, shoulders and subtalar joints are less frequently involved. Wrists, fingers and toes are rarely involved. Fortunately, hemophilic arthropathy of the spine facet joints does not occur. Following an initial bleed, progression to chronic synovitis and advanced arthropathy is common.