Introduction
Ankylosing spondylitis is an inflammatory condition that affects young adults. This condition occurs more in males than females, and affects the spine, sacroiliac joints, and other large joints, such as the hip.
Ankylosing means “rigid” or “fusion”, and spondy means “spine”, so the vertebrae of the spine are fusing together.
Spondylitis is inflammation of the spine. The patient will have inflammation followed by fusion of the spine and the sacroiliac joints. Therefore, the patient may complain of morning stiffness, low back pain, and possibly hip pain. Other large joints, like the hip, may also be affected. The pain associated with ankylosing spondylitis gets better with exercise, and not with rest.
Differentiating between Rheumatoid Arthritis
There is a difference between Rheumatoid arthritis and ankylosing spondylitis. Rheumatoid arthritis affects the synovial lining of joints and affects predominantly the cervical spine. On the other hand, ankylosing spondylitis affects ligaments, tendons, discs, and some joints, and it will affect the entire axial spine.
Ankylosing spondylitis is a systemic problem that involves the immune system. It is similar to rheumatoid arthritis, but with a negative rheumatoid factor.
A characteristic of ankylosing spondylitis is that it is part of the seronegative spondyloathropathy, which means that the rheumatoid factor is negative. However, Even though the rheumatoid factor is negative, the HLA-B27 is positive.
Risk Factors
Risk factors associated with ankylosing spondylitis include young males, positive family history of ankylosing spondylitis, and HLA-B27 positive.
HLA-B27 Antigen
HLA-B27 is part of our immune system. It is an antigen that will be on the surface of the cell. It is likely that it has the same amino acid sequence of the protein produced by the bacteria klebsiella pneumoniae, by food, and by other things. When the immune system identifies this protein as it goes through the blood stream, T-cells can recognize the HLA-B27 antigen that is on the surface of the cells. When the T-cells of a patient with ankylosing spondylitis recognize the HLA-B27 antigen, they recognize it as bad and will then attack it. This will then recruit other cells to attack the HLA-B27 antigen as well. Therefore, everything that contains HLA-B27, such a tendons, ligaments, joints, etc., will be attacked because the T-cells think they are a foreign protein. The protein produced by the bacterium and by the HLA-27, for example, have the same sequence, which means the immune system cannot differentiate between them. This is why ankylosing spondylitis is classified as an autoimmune disease.
Diagnosis
Ankylosing spondylitis is a difficult condition to diagnose. A “bamboo spine” will be seen on x-ray. There will also be sacroiliac joint involvement, which is characteristic of ankylosing spondylitis, and the sacroiliac joints will start fusing. There may also by a systemic autoimmune response that will cause fever and malaise. There will be redness and inflammation of the eye, called uveitis. Aortic inflammation, which could lead to aortic aneurysm if the aorta is dilated, or aortic regurgitation may also be present in patients with ankylosing spondylitis. Finally, the patient may have depression.
Pateints with ankylosing spondylitis will have fusion of the spine, and hence, the spine will not have any free movement. The patient will complains of gradual stiffening of the spine and limited chest wall expansion. Less than 2 cm. of chest wall expansion is more diagnostic than the HLA-B27 blood test.
When a blood test is taken of a person with ankylosing spondylitis, it will be HLA-B27 positive. The erythrocyte sedimentations rate and C-reactive protein count may both be elevated.
Treatment
To treat ankylosing spondylitis, management that deceases inflammation is usually done. These include anti-inflammatory medications, physical therapy to improve flexibility and strength of the spine and joints, and TNF alpha blocking agents.
