Ankylosing Spondylitis (AS) is a chronic, multi-system inflammatory disease. It causes progressive arthritis causing inflammation of the primarily the sacroiliac joints and the spine. It can also affect other joints and organs. This disease causes the spine to stiffen from joint inflammation and may even cause the spine to fuse. Complete fusing together of the vertebrae is called ankylosis. Ankylosing Spondylitis is among a class of diseases called a spondyloarthropathy. It may be found in conjunction with other spondyloarthropathies, including reactive arthritis, psoriatic arthritis, ulcerative colitis and Crohn disease.
AS primarily affects Caucasian adult males between the ages of 17 and 35 and is three times more common in males than females. While the cause of AS remains unknown, there does appear to be a strong genetic component. A specific gene, HLA-B27, is present in 90-95% of Caucasian people with AS. Approximately 8% of healthy Caucasian Americans have the HLA-B27 gene, however only about 1% of those people will develop the disease. There are probably four to five other genes that influence whether or not a person develops AS.
When AS first appears, it usually causes inflammation of the sacroiliac joints at the base of the spine. Sacroiliitis can cause pain in the low back and buttocks and be coupled with low back pain. Learn more about sacroiliac joint pain.
Pain usually progresses gradually over time, often over many months or even years. Symptoms are worse in the morning, worse with inactivity and rest and improve with activity. Chronic pain and stiffness are the most common complaints. Fatigue is also another common complaint found in 65% of patients. Inflammatory back pain is typically dull pain around the sacroiliac joints and buttocks. Patients may have intermittent flares of pain and inflammation with periods of remission.
Inflammatory cells release chemicals that damage the bone. The body responds by continually trying to repair bone with scar tissue and new bone tissues, leading to overall weaker bones. As the inflammation progresses to involve more of the spine, there is decreased flexibility and range of motion of the spine. Pain may present along the spine and involve many spinal joints. In the mid back, progression can cause a rounding of the spine called kyphosis. If the joints where the ribs attach are involved, breathing can become affected as the lungs may be restricted in expanding. Calcium deposits are formed to try to strengthen joints and the bone, eventually fusing the spine. If vertebrae fuse together, the spine is no longer mobile. This coupled with weak bones places an increased risk for fractures.
Ankylosing Spondylitis can be challenging to diagnose in the early stages. It is generally made by combining clinical criteria of inflammatory back pain and arthritis with radiological findings. Your doctor will take a medical history and perform a physical exam. Other diagnostic tests including x-rays and lab tests will likely be used. On x-rays, the vertebral bodies have a square shape and characteristically look like a "bamboo spine." There is a blood test for the HLA-B27 gene where if positive, increase the likelihood you have AS with other history and exam findings. Blood work may also show overall increased inflammation in the body.
There is no cure for AS, but there are effective treatments to help relieve pain and improve symptoms. Ankylosing Spondylitis is generally treated conservatively with use of medication, physical therapy, and exercise. Medications are used to reduce inflammation and pain. A well-rounded rehabilitation program with a physical therapist is used to reduce pain and inflammation, improve mobility and strength, and help establish a daily spinal health program. Spinal surgery is uncommon, usually only reserved for patients with resulting severe deformity. Long standing arthritis in the hips may require an artificial hip replacement.