Ankylosing spondylitis is a form of arthritis which is characterized by inflammation of the joints between the vertebrae of spine. It may lead to stiffness and pain in different body parts such as neck, back, jaw and hips and it may also involve some other organs such as heart, eyes, kidneys and lungs. This kind of arthritis is more common in males than in females and can affect all age groups. Men may develop the inflammation of pelvis, spine, shoulders and chest wall, while women may have the inflammation of hips, pelvis, wrists and knees.

Although medical science is not clear about the exact causes of ankylosing spondylitis, some genetic factors contribute to the development of this disease. The genetic marker, HLA-B27 is the most significant gene responsible for development of this disorder. Recently, two more genes such as IL23R and ARTS1 are identified which are associated with ankylosing spondylitis. A person with the age less than 40 and positive for HLA-B27 gene and having the family history of ankylosing spondylitis is at the higher risk of developing this disease.

The major risk factors for ankylosing spondylitis are positive HLA-B27 maker, family history of ankylosing spondylitis and frequent gastrointestinal infections. Onset of this disease is more common in younger people between the age group of 17-35. However, it may affect older people as well as children. It more commonly affects men than women.

A person with genetic predisposition, immune response mediators and inflammatory bowel disease is at the higher risk of developing this disease. Genetic predisposition is one of the significant causes of ankylosing arthritis. About 90% of patients with this disorder are positive for HLA-B27 gene. If either parent has HLA-B27 gene, there are about 50% chances of passing-on this gene to their child. But, the possibility of developing ankylosing spondylitis in the child is less than 10%.

Some bacterial infections act as triggering factors for the underlying chronic inflammation which can lead to the development of ankylosing spondylitis. The excessive immune response to the gastrointestinal bacterial infections such as ulcerative colitis and Crohn’s disease can cause the underlying pathogenesis of ankylosing spondylitis.

Ankylosing spondylitis is supposed to be associated with the secretion of cytokines such as TNF-alpha. The secretion of these immune response mediators is because of prolonged immune response to the infection. There may be elevated levels of TNF-alpha in the sacroiliac joints of the patients with ankylosing spondylitis.

Other possible causes of ankylosing spondylitis are trauma such as cervical spine fracture, epidural hematoma, subarachnoid hemorrhage and rotary atlantoaxial subluxation, infections like meningitis, cervical lymphadentitis, epiglottitis, epidural abscess and discitis, torticollis, tumors and dystonic reaction.