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What is ankylosing spondylitis?
Ankylosing spondylitis is a form of inflammatory arthritis. It affects the joints of the spine, in particular the sacroiliac joint at the bottom of the spine. Ankylosing spondylitis causes the swelling of the ligaments, discs and joints between the vertebrae of the spine. Symptoms include pain and stiffness in the lower back and over time, fusion of the vertebrae can occur.
The specific cause of ankylosing spondylitis is unknown, although genetic factors appear to play a role. The presence of a specific gene that produces the antigen HLA-B27, is found in nine out of 10 people with ankylosing spondylitis, although there are people with the gene that do not develop the condition.  It is therefore thought that other factors are involved in triggering ankylosing spondylitis.
Ankylosing spondylitis can begin to develop from the age of 15 years and generally affects young adults before the age of 35 years. The condition begins with inflammation of the sacroiliac joint and facet joint. Over time, bony growths can begin to form and cause fusion of vertebrae, causing limited movement and pain in the lower back.
Risk factors associated with developing the condition include:
Signs and symptoms
The signs and symptoms of ankylosing spondylitis include:
- Lower back pain that gradually appears over time, is worse after rest and improves after exercise;
- Stiffness that worsens in the morning;
- Buttock, hip or shoulder pain;
- Limited mobility of the spine;
- Head-forward posture or neck pain;
- Pain in ligaments and tendons that are attached to the spine, for example, the back of the heel, and;
- Eye pain, light sensitivity or blurred vision.
The signs and symptoms can improve, worsen, or stop entirely at irregular intervals.
Methods for diagnosis
Identifying ankylosing spondylitis early is important in preventing any damage to the spine. In many cases there can be a delay of 5-7 years from the time symptoms first appear to when the condition is diagnosed.  In addition to reviewing the medical history, diagnosis of ankylosing spondylitis can be determined by the following tests:
- A physical examination;
- An X-ray to identify any changes in bones and joints;
- A computerised tomography (CT) scan to assist with early diagnosis;
- A magnetic resonance imaging (MRI) scan to enable visualisation of the inflammatory changes in the spine;
- Blood tests to check for evidence of inflammation, and;
- Genetic testing to check for the presence of the HLA-B27-causing gene.
Types of treatment
Currently there is no cure for ankylosing spondylitis. The main goal of treatment is to maintain a good quality of life by managing the symptoms and reducing the progression of the condition. Treatments include medications, physiotherapy and surgery.
Medications used in the treatment of ankylosing spondylitis include:
- Non-steroidal anti-inflammatory drugs (NSAIDs) to reduce inflammation and control pain and stiffness;
- Disease-modifying antirheumatic drugs (DMARDs), which can slow the progression of the condition;
- Tumour necrosis factor (TNF) inhibitors to control inflammation, and;
Physiotherapy is also commonly used to manage ankylosing spondylitis. This can include using specific exercises to reduce the pain and increase the strength and flexibility of the muscles and tendons in the affected area. Your doctor or physiotherapist can tailor an exercise program and other therapies, such as hydrotherapy, to help improve mobility of the spine.
In most cases, surgery is not necessary, but can be utilised if there is extreme pain or joint damage. Joints can be surgically fused or repaired, depending on the location and degree of damage to a joint.
In severe forms of ankylosing spondylitis, it is possible for sections of the spine to become fused, causing stiffness and immobility. This can cause the natural curves of the spine to straighten, forcing the body into a hunched position. The rib cage can also become stiff, which can reduce the capacity of the lungs and cause breathlessness. Osteoporosis is a common complication, which can increase the risk of sustaining a fracture.
The prognosis can depend on how early the condition is diagnosed. In some cases, only mild symptoms are experienced at irregular intervals and full physical activity is possible. In other cases, symptoms can be more frequent and complications, including spinal fusion, can occur. Treatment with medications and physiotherapy are important, after a confirmed diagnosis, to achieve the best outcome.
There are no specific ways to prevent ankylosing spondylitis. It is, however, possible to slow its progression and minimise risk of developing complications through early diagnosis and timely use of specific treatments.