Axial Spondyloarthritis

Medically Reviewed By William C. Lloyd III, MD, FACS
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What is axial spondyloarthritis?

Spondyloarthritis (SpA) is an umbrella term for a group of rheumatic inflammatory diseases. Axial refers to the joints of the spine, chest and pelvis. So, axial spondyloarthritis is a chronic inflammatory disease of these joints. SpA differs from other kinds of arthritis because it involves entheses. Entheses are sites where ligaments and tendons attach to bones.

There is some confusion surrounding SpA because spondyloarthritis diseases have a new and an old classification. Under the traditional system, ankylosing spondylitis was the term for arthritis primarily affecting the spine. Inflammation would eventually trigger ankylosis—new bone formation leading to fusion of vertebrae. Other terms described inflammation in sites outside the spine.

The new system classifies the group of diseases as either axial spondyloarthritis (AxSpA) or peripheral spondyloarthritis (pSpA). AxSpA involves the axial joints of the spine and pelvis. When inflammation affects joints outside the spine, it is pSpA. This can include the fingers, hands, wrists, elbows, knees, ankles, feet and toes.

The system then separates AxSpA into two types:

  • Radiographic axial spondyloarthritis (r-AxSpA) shows up on X-rays as damage to the spine or pelvic joints. Ankylosis with fusing of the vertebrae may be present. Ankylosing spondylitis falls under this category.
  • Non-radiographic axial spondyloarthritis (nr-AxSpA) lacks X-ray evidence of damage or fusion. However, an MRI (magnetic resonance imaging) exam may show signs of active inflammation.

The two categories are basically different phases of the same disease. Everyone with r-AxSpA had nr-AxSpA at one point. However, not all people with nr-AxSpA will progress to have damage you can see on X-ray. Research suggests up to 30% of people with nrAxSpA will progress to r-AxSpA. Risk factors for progression include being male and having high blood levels of C-reactive protein.

AxSpA typically starts during the late teens or young adult years. The most common symptom is lower back pain, lasting more than three months. The pain and stiffness usually begins gradually and becomes chronic. When AxSpA involves the ribs, it can be hard to expand the chest and take deep breaths.

The cause of AxSpA is unclear. There seems to be a very strong genetic component. Scientists have found at least 30 genes that play a role in the disease. The most common one is HLA-B27.

First-line treatment for AxSpA includes physical therapy and NSAIDs (nonsteroidal anti-inflammatory drugs). If these treatments fail, doctors may recommend biologic medicines. Spinal surgery is not usually necessary. However, hip replacement surgery can help when the hip has severe damage.

See your doctor if you have lower back pain or stiffness that persists.

What are the symptoms of axial spondyloarthritis?

Axial spondyloarthritis symptoms usually appear before age 40 to 45 years. They most commonly start during late adolescence or early adulthood. Typically, people notice symptoms gradually over weeks or months. Symptoms may start on one side or alternate sides. They can also flare and resolve over a period of time. Eventually, symptoms become chronic and affect both sides.

Common axial spondyloarthritis symptoms

The most common AxSpA symptoms are lower back pain and stiffness. The pain and stiffness may also affect the hips and buttocks. Symptoms tend to be worse in the morning or after periods of inactivity. Sometimes, pain and stiffness will cause problems staying asleep during the night. Being active and light stretching tends to relieve the pain and stiffness.

Over the course of the disease, the pain and stiffness can spread to the neck, shoulders, ribs and heels. When the ribs are involved, it can be difficult to expand the chest. This makes it hard to take deep breaths and can eventually affect lung function. For people who develop ankylosing spondylitis, fusion of the spinal vertebrae can occur. This limits spinal mobility and flexibility.

Other possible AxSpA symptoms can include:

Serious symptoms that might indicate a serious condition

Sometimes, people with AxSpA can have involvement outside the joints. This includes bowel inflammation and inflammation of the eye.

Seek immediate medical, preferably from an eye specialist, for any of the following symptoms:

See your doctor for lower back pain or stiffness that isn’t getting better. There can be several causes of chronic lower back pain. It may take the expertise of a rheumatologist to properly diagnose AxSpA.

What causes axial spondyloarthritis?

Inflammation is the cause of the pain and stiffness of AxSpA. But experts do not fully understand what triggers it. It seems to be hereditary and scientists have identified at least 30 genes that may be involved. The major one is HLA-B27. This gene is normal, not a mutation. About 2% of people born with HLA-B27 will go on to develop AxSpA. And scientists have found a strong link between HLA-B27 and AxSpA in certain racial groups. For example, more than 95% of Caucasians with ankylosing spondylitis have the gene. The same is true for nearly 80% of people from Mediterranean countries with ankylosing spondylitis.

What are the risk factors for axial spondyloarthritis?

A number of factors increase the risk of developing AxSpA. However, not all people with risk factors will get AxSpA. Risk factors include:

  • Age less than 45 years
  • Family history of AxSpA
  • Male sex
  • Presence of HLA-B27 gene

Reducing your risk of axial spondyloarthritis

There is no reliable way to prevent AxSpA. If you have a family history of the disease, talk with your doctor.

How is axial spondyloarthritis treated?

First-line axial spondyloarthritis treatment consists of physical therapy and medications. A therapist can work with you to develop a personalized plan. This will include axial spondyloarthritis exercises to relieve symptoms and improve spinal mobility. Doctors will likely prescribe NSAIDs (nonsteroidal anti-inflammatory drugs) to go along with physical therapy.

If first-line treatment fails to relieve symptoms, doctors may recommend a biologic. Biologic medications target proteins involved in inflammation. Biologics for AxSpA include:

Doctors rarely recommend spinal surgery for AxSpA. In some cases, surgery can help when there is severe damage, especially to a joint like the hip.

What are the potential complications of axial spondyloarthritis?

Spinal fusion due to ankylosis is the major complication of AxSpA. When two or more vertebrae fuse, you lose mobility between them. This results in spinal stiffness and loss of flexibility. It can also affect the ability of your ribcage to expand. This can eventually affect your lung function.

AxSpA complications can also involve:

  • Eye inflammation, which requires immediate medical care
  • Heart valve problems due to inflammation of the aorta
  • Intestinal inflammation
  • Jaw ligament inflammation, making chewing and eating difficult
  • Osteoporosis and compression fractures
  • Psoriasis
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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2020 Apr 8
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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