Ankylosing spondylitis, a form of arthritis in the spine, is one of the most common spinal inflammatory disorders. Ankylosing spondylitis can cause severe pain and disability, especially if left untreated.
Ankylosing spondylitis causes inflammation in the areas where soft tissues (ligaments and tendons) attach to bone in the spine. Ankylosing spondylitis also affects the sacroiliac (SI) joints, which are the joints between the spine and the pelvis. Inflammation in a joint causes some of the tissue to erode, and when the inflammation subsides, new bone may grow in its place. As a result, the vertebrae and joints grow together (fuse), and the spine becomes less flexible.
Ankylosing spondylitis can cause various patterns of back pain. Patients with ankylosing spondylitis usually experience slow-onset pain. Some patients experience chronic pain, and some have pain that comes and goes. The pain usually is more severe at night and is associated with stiffness in the morning.
Ankylosing spondylitis causes the spine to become less flexible, and as a result can cause a forward curvature of the spine called kyphosis.
Patients with this condition can also experience pain, swelling, and stiffness in other parts of the body as the disease progresses to affect shoulders, hips, ribs, heels, and even the small joints of the hands and feet.
In some cases, ankylosing spondylitis may also affect the eyes (iritis or uveitis). Rarely, ankylosing spondylitis can also cause complications involving the heart and lungs.
To diagnose ankylosing spondylitis, a doctor will often perform full physical examination and order blood tests that can detect the presence of inflammation.
The doctor may also order X-rays to visualize the changes in the spine and identify bony growths.
Since there seems to be a connection between ankylosing spondylitis and a specific gene (HLA-B27), the doctor may order a genetic test to see if this particular gene is present.
The exact causes of ankylosing spondylitis are unknown, but both genes and the environment seem to play a role.
About 90% of patients with ankylosing spondylitis carry a specific gene called HLA-B27. However, HLA-B27 does not tell the whole story: the remaining 10% of people with ankylosing spondylosis do not carry the gene. And many people in the general population carry HLA-B27, but a majority of them will never develop the condition. Other genetic and/or environmental factors, therefore, play a role in ankylosing spondylosis, but the identities and exact mechanisms of these other factors are not yet known.
Unlike other types of arthritis, ankylosing spondylitis can affect younger people. It typically affects men between the ages of 17–45, though it can affect anyone.
Although there is no cure for ankylosing spondylitis, available treatments help to reduce symptoms.
Before surgical treatments are discussed, patients with ankylosing spondylitis are typically prescribed certain medications, which may include nonsteroidal anti-inflammatory drugs (NSAIDs), muscle relaxants, corticosteroids, disease-modifying antirheumatic drugs (DMARDs), and biologics. These medications help reduce the inflammation and, therefore, help to reduce pain.
The surgeon will recommend strengthening exercises and range of motion exercise as well as a healthy diet.
Surgery may be necessary, especially to repair the fractures that may be caused by ankylosing spondylitis. If these fractures have begun to press on the spinal cord and surrounding nerves, surgery to decompress the spinal cord may be necessary. In these cases, the surgeon may perform a laminectomy to remove the lamina, which is the bone that covers the spinal canal. Removing the lamina makes room for the spinal cord and allows the spinal cord to function properly.
In some situations, the surgeon may perform a spinal fusion to ensure the spinal column is stable after surgery. During a spinal fusion, the surgeon may place a bone graft in the open space and allow the bones to fuse (grow together). Spinal instrumentation with metal rods and screws may be used to provide immediate stability to the spine to allow more rapid healing of the bone fusion. This enables the patient to be mobile and more independent right after surgery.
In rare cases, the surgeon may select to perform an osteotomy, which is performed to straighten the spine that has moved into a forward curvature position.