Ankylosing spondylitis (AS), also called Morbus Bechterew or spondylitis ankylosans, is a systemic disease characterised by painful inflammation of the axial skeleton, the large peripheral joints, and the digits. Occasionally, other joints or organs can be involved. Currently it is believed that AS is caused by an autoimmune reaction; ankylosing spondylitis is assumed to be an autoimmune disease.
Predominant symptoms are marked back stiffness and stiffness of hips, neck and the chest wall. In about 40% of patients the eyes are affected with inflammation called uveitis or iritis. Back stiffness due to ankylosing spondylitis is often improved after exercise. Ankylosing spondylitis affects men more than women. Most patients (90% of the Kaukasian population) show a genetic marker called HLA-B27. However, this gene doesn’t necessarily lead to ankylosing spondylitis.
The disease is usually diagnosed during the teenage years, the twenties, or thirties. Particularly in young men ankylosing spondylitis should be suspected in patients with nocturnal back pain and kyphosis, diminished chest expansion, Achilles tendinitis, or unexplained anterior uveitis. Diagnosis requires showing sacroiliitis on x-ray or magnetic resonance imaging. ESR and other acute-phase reactants (e.g., C-reactive protein) are inconsistently elevated in patients with active AS. Laboratory tests for rheumatoid factor and antinuclear antibodies (ANA) are negative.