Ankylosing spondylitis is a form of arthritis that mainly affects the spine and sacroiliac joints, or the lower back.

An inflammatory disease, symptoms of ankylosing spondylitis (AS) include pain, stiffness, and loss of mobility. The disease involves erosion of bone and increased bone formation in the spine, leading to bone fusion. In advanced cases, this can lead to spinal deformity.

AS most commonly occurs in men in their teens and 20s, but it can affect anyone of any age. It tends to be milder when it does occur in women, making it harder to diagnose.

Drug treatments and physical therapy can help relieve symptoms.

Fast facts on ankylosing spondylitis (AS):

  • Ankylosing spondylitis is a type of arthritis.
  • It mostly affects the lower part of the spine, and where it joins to the hips, known as the sacroiliac joints.
  • Ankylosing spondylitis can be difficult to diagnose but has a particular pattern of pain symptoms, and changes can be seen on X-ray and MRI.
  • There is no cure, but drugs can help manage the pain and inflammation. Physical therapy can also relieve and prevent some of the effects.

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One of the common symptoms of ankylosing spondylitis is lower back pain.

The three main symptoms of AS are:

  • pain
  • stiffness
  • loss of mobility

Pain is the main symptom, especially in the lower back and buttock areas during the early stages.

However, inflammation and pain are not confined to the spine. It is a systemic condition, which means it can affect other parts of the body.

These include:

  • other joints
  • the neck
  • the top of the shin bone in the lower leg
  • behind the heel of the foot, in the Achilles tendon
  • under the heel of the foot

AS can cause so-called bony fusion, an overgrowth of bones at the joints. This can make it difficult to carry out everyday tasks. In some cases, it can restrict movement of the chest and make it hard to breathe.

People with AS may also experience fatigue, a feeling of being tired and lacking energy.

AS can also affect the eyes, including the iris and other parts. This inflammation, known as iritis or uveitis, depending on the location, can cause redness and pain. It can impair vision if not treated.

Other systemic signs of the disease may include neurological and cardiovascular changes.

Below is a 3-D model of ankylosing spondylitis, which is fully interactive.

Explore the model using your mouse pad or touchscreen to understand more about ankylosing spondylitis.

There is no cure for AS, and the damage cannot be reversed. However, some options can help relieve symptoms and manage progression.

These include:

  • physical therapies and exercises
  • advice
  • drugs
  • surgery, in rare cases

The person will need to see a specialist doctor, known as a rheumatologist. They may need a number of visits, as the disease progresses slowly. Medical care enables better monitoring and treatment.

Two approaches commonly used to manage AS are:

  • drugs to reduce pain and inflammation
  • physical therapy and exercises to maintain movement and posture

Surgery is used only rarely, in severe cases, to correct severe deformity, such as excessive bending of the spine, or to replace a hip or other joint.

Drug treatment

The main drugs used to ease the pain and inflammation of AS are nonsteroidal anti-inflammatory drugs (NSAIDs). Examples include ibuprofen, naproxen, and diclofenac. Acetaminophen and codeine are also options if NSAIDs are unsuitable or insufficient.

Some NSAIDs compromise bone health by reducing the creation of new bone, and NSAIDs are not usually recommended after surgery for people with bone fusion problems.

Other drug options include:

  • locally injected corticosteroids
  • disease-modifying anti-rheumatic drugs (DMARDs), such as sulfasalazine (brand names: Azulfidine or Sulfazine) and methotrexate (Otrexup, Rheumatrex, or Trexall)
  • tumor necrosis factor (TNF) antagonists, such as adalimumab (Humira), certolizumab (Cimzia), etanercept (Enbrel), golimumab (Simponi), or infliximab (Remicade)
  • other biologic treatments, such as secukinumab (Cosentyx)

TNF treatment appears to be effective, but it is expensive and can have adverse effects.

AS can affect the whole body, and patients may meet with a range of specialists, including physical therapists, eye specialists, and gastroenterologists.

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Physical therapy can help relieve the symptoms of ankylosing spondylitis.

Physical therapy and exercises can help prevent symptoms.

A physical therapist will design a program that can help patients maintain good posture and motion in the joints.

This might include:

  • daily exercises
  • special training
  • therapeutic exercises

Physical therapy exercises are referred to as strengthening exercises and range-of-motion exercises.

Here are two exercises, suggested by the U.K. charity, Versus Arthritis:

1. Stand with your back and heels against a wall, and push your head back to touch the wall. Do not tilt the head back. Hold for 5 seconds, relax, and repeat for up to 10 times.

2. Stand with the feet apart and hands on hips. Turn to one side, hold for 5 seconds, and relax. Repeat on the other side. Do this five times on each side.

There are different ways to exercise, including water fitness. A doctor can recommend a suitable plan.

A doctor will ask about symptoms, carry out a physical examination, and arrange for tests where necessary.

If inflammatory back pain is present with certain features, this may indicate AS.

The features include:

  • pain that does not improve with rest
  • pain that causes sleep disturbance
  • back pain that starts gradually, before the age of 40 years, and is not caused by injury
  • symptoms that persist for over 3 months
  • spinal stiffness in the mornings, which improves with exercise and motion

Imaging tests may confirm the diagnosis, but changes may not be immediately visible on such tests. This can delay diagnosis.

Blood tests

No blood test can confirm AS, but tests can help confirm diagnosis and rule out other causes.

The tests for inflammation may include:

  • erythrocyte sedimentation rate (ESR)
  • C-reactive protein (CRP)
  • complete blood count (CBC)
  • genetic test (HLA B27)

If other causes, such as rheumatoid arthritis (RA) are suspected, testing for rheumatoid factor (RF), cyclic citrullinated peptide (CCP), and antinuclear antibodies (ANA) can help rule out these conditions.

Imaging tests

These may include:

  • X-rays, which can reveal both early and more advanced changes to the spine and pelvis
  • MRI, for example, an MRI of sacroiliac (SI) joints can reveal early signs of the condition

The exact cause of AS remains unclear, but the symptoms result from inflammation in parts of the lower spine.

When new bone grows, this inflammation can lead to damage and fusion. The fusion can happen as a result of the inflammation of the tissues that connect to bones.

However, it is not yet known why this chronic inflammatory process occurs in people with ankylosing spondylitis.

The condition often runs in families and is known to have a genetic component.

The prognosis for AS is difficult to predict, as it varies widely between individuals, and the progression is often not constant.

Important factors for measuring outlook include levels of functional ability, spinal mobility, joint damage, and so on. Some people will experience severe functional loss, some hardly notice their symptoms, and around 1 percent experience remission, where symptoms cease to develop.

A few people will have life-threatening complications, affecting the heart, lungs, or intestines.

Males who develop symptoms at a younger age are more likely to have severe damage and loss of mobility, but in women, the impact appears to be less severe.

Smoking has been linked to poorer outcomes.