Ankylosing Spondylitis

Spondyloarthritis, often shortened to SpA, is a group of inflammatory conditions that can affect the spine, joints and places where tendons or ligaments attach to bone. It may cause back pain and stiffness, swollen joints, or pain at sites such as the heel.

The pattern varies. Some people mainly have symptoms in the back and pelvis; others mainly have symptoms in the arms and legs. SpA can also be associated with inflammation in the eyes, psoriasis or inflammatory bowel disease.

What are the different types of spondyloarthritis?

The terms can be confusing because they describe both where inflammation occurs and conditions that may accompany it.

• Axial spondyloarthritis mainly affects the sacroiliac joints, where the spine meets the pelvis, and sometimes the spine itself. It may also affect other joints and tendons.
• Ankylosing spondylitis, or AS, is a form of axial spondyloarthritis in which characteristic changes can be seen on X-rays. It is also called radiographic axial spondyloarthritis.
• Non-radiographic axial spondyloarthritis causes a similar pattern of symptoms, but the characteristic changes are not visible on ordinary X-rays. An MRI may show inflammation in some people.
• Peripheral spondyloarthritis mainly affects joints or tendon-attachment sites outside the spine, such as the knees, ankles, feet or heels.
• Psoriatic arthritis is a related form that may occur in people with psoriasis, although the skin condition is not always obvious.
• SpA can also occur in association with inflammatory bowel disease or sometimes after certain infections, when it may be called reactive arthritis.

These categories can overlap. Your rheumatologist will explain which description best fits your symptoms and test results.

What causes spondyloarthritis?

SpA develops when the immune system causes inflammation in certain joints and tissues. Its exact cause is not fully understood. Genes contribute to risk, but they are only part of the explanation.

One gene marker, HLA-B27, is associated with axial spondyloarthritis. Many people with HLA-B27 never develop the condition, and some people with SpA do not have the marker. You cannot diagnose or rule out SpA from this blood test alone.

SpA is not contagious. Having it is not your fault.

What does inflammatory back pain feel like?

Back pain is common and has many possible causes. Back pain related to axial SpA often has a particular pattern:

• It begins gradually, often before the age of 45.
• It lasts for several months.
• It is worse after resting or first thing in the morning.
• It tends to improve with movement or exercise.
• It may disturb sleep, especially during the second half of the night.
• It can be felt deep in the buttocks, sometimes alternating from one side to the other.

Not everyone has every feature. Having this pattern does not automatically mean you have SpA, but it is a reason to discuss the possibility with a clinician.

What other symptoms can occur?

Depending on the type of SpA, you may have:

• Pain or swelling in joints such as the knees, ankles or hips
• Pain where a tendon attaches to bone, particularly at the back or underside of the heel
• A whole finger or toe that becomes swollen, sometimes called a sausage digit
• Neck, chest-wall or rib pain and stiffness
• Tiredness, especially when inflammation is active

Some people have symptoms that come and go. Others have more persistent symptoms. Tell your clinician which activities are difficult for you, as well as where you feel pain.

Can spondyloarthritis affect the eyes, skin or bowel?

Yes. Some people with SpA also have:

• Uveitis: Inflammation inside the eye that can cause a suddenly painful, red eye, sensitivity to light or blurred vision.
• Psoriasis: Inflamed, scaly skin patches. Nail changes may also occur.
• Inflammatory bowel disease: Conditions such as Crohn’s disease or ulcerative colitis, which may cause persistent diarrhoea, abdominal pain or blood in the stool.

A painful red eye with light sensitivity or blurred vision needs urgent assessment by an eye specialist. Tell the eye team if you have SpA. Also tell your rheumatologist about any psoriasis or bowel symptoms, because these can affect the choice of treatment.

How is spondyloarthritis diagnosed?

There is no single test that proves or excludes SpA. Your rheumatologist considers your symptoms, examines your spine and joints, and looks for clues such as heel tenderness, psoriasis, uveitis or bowel disease.

Investigations may include:

• Blood tests for inflammation, such as CRP or ESR, and sometimes HLA-B27
• X-rays, particularly of the sacroiliac joints
• MRI, which can sometimes show inflammation before changes appear on an X-ray
• Other tests if your symptoms suggest another condition

Normal CRP or ESR results do not rule out SpA. A negative HLA-B27 result does not rule it out either. X-rays may also be normal, especially earlier in axial disease. Your rheumatologist will interpret scans alongside your history and examination; an MRI finding on its own may have more than one explanation.

Will my spine become fused?

Most people with axial SpA do not develop a completely fused spine. In some people with longstanding ankylosing spondylitis, ongoing inflammation is associated with new bone formation that makes parts of the spine less flexible.

The course differs considerably between individuals. Follow-up helps your team assess symptoms, movement, treatment response and any complications. Do not assume that someone else’s experience predicts yours.

How is spondyloarthritis treated?

Treatment aims to control inflammation and pain, maintain movement and function, and address any eye, skin or bowel problems. The plan depends on which parts of your body are affected, how active the condition is, other illnesses and your response to treatment.

Exercise and physiotherapy

Regular exercise is a central part of axial SpA care. It helps maintain spinal movement, strength, fitness and posture. A physiotherapist can help you choose a programme that suits your symptoms and abilities.

Your plan may include mobility exercises, strengthening, aerobic activity and attention to posture. Walking, swimming and other activities you can sustain may also be useful. Begin at a manageable level and build up gradually. If a particular movement causes marked or persistent pain, ask your physiotherapist or clinician how to adapt it.

Exercise remains important even when you take effective medication.

Non-steroidal anti-inflammatory drugs

Non-steroidal anti-inflammatory drugs, or NSAIDs, can reduce pain and stiffness in axial SpA. Examples include medicines such as naproxen and ibuprofen. Your clinician will consider the dose and duration that are appropriate for you.

NSAIDs can cause problems for some people, particularly those with stomach ulcers, kidney disease, certain heart conditions or medicines that increase bleeding risk. Do not take more than one NSAID together unless your clinician specifically advises it. Tell your team if a medicine is not helping or causes side effects.

Biologic and targeted medicines

If axial SpA remains active despite an appropriate treatment plan, your rheumatologist may discuss a biologic or targeted medicine. These medicines act on particular pathways involved in inflammation. Examples include TNF inhibitors, IL-17 inhibitors and, for some patients, JAK inhibitors.

The best choice depends on your overall health and whether you also have uveitis, psoriasis or inflammatory bowel disease. Before treatment, you may need checks for infections such as tuberculosis and hepatitis, along with a vaccination review. Your team will explain the expected benefit, risks and follow-up for the medicine selected.

Treatment for peripheral symptoms

Treatment for swollen joints in the arms or legs may differ from treatment for spinal symptoms. Your rheumatologist may consider a local steroid injection or a conventional disease-modifying medicine such as sulfasalazine in selected circumstances.

Medicines such as sulfasalazine or methotrexate are not generally effective for inflammation confined to the spine. They may have a role for particular peripheral or associated conditions. This is why the location of your symptoms matters when treatment is chosen.

Surgery is uncommon but may be considered for severe damage in a joint such as the hip, or for selected spinal complications.

What can I do day to day?

Keep a sustainable movement routine

Short, regular sessions are often easier to maintain than occasional intense exercise. Include movement during days when you have been sitting for a long time. Ask for an individual exercise plan if you are unsure where to begin or have limited mobility.

Avoid smoking

Smoking is associated with poorer outcomes in axial SpA and also harms heart and lung health. If you smoke, ask your healthcare team for help to stop.

Look after your bones and general health

Discuss your bone health, nutrition and any need for calcium or vitamin D with your clinician. Supplements are most useful when there is a specific need; there is no special diet that cures SpA.

Make daily tasks easier

If stiffness makes dressing, work or travel difficult, a physiotherapist or occupational therapist can suggest changes. A long-handled shoehorn, suitable chair or adjustments to your workspace may help. Tell your team if your condition is affecting sleep, employment or mood.

What if I have longstanding spinal stiffness?

A very stiff or fused spine can be more vulnerable to injury after a fall or accident. If you have been told that your spine is significantly fused, discuss suitable activity and fall-prevention measures with your healthcare team.

After a fall or accident, seek urgent medical assessment if you develop new neck or back pain, even if the injury seemed minor. New weakness, numbness or difficulty controlling your bladder or bowel needs emergency assessment.

Advice about pillows, mattresses or posture should be tailored to your comfort and spinal mobility. There is no single pillow thickness that is right for everyone.

What if I want to become pregnant?

Many people with SpA have healthy pregnancies. Speak with your rheumatologist before trying to conceive so you can review disease control and medicines. Some treatments may need to be changed beforehand, while others can be continued in selected circumstances.

Tell your team if you become pregnant or plan to breastfeed. Do not stop treatment without discussing what will control your symptoms in its place.

When should I seek medical help?

Seek urgent eye care for a painful red eye, sensitivity to light or a new change in vision.

Seek urgent medical assessment after a fall or accident if you have significant spinal stiffness and develop new neck or back pain. New weakness, numbness, or loss of bladder or bowel control needs emergency care.

Contact your rheumatology team if back pain or stiffness is worsening, a joint becomes newly swollen, treatment is not helping, or you develop troublesome side effects. Tell them about new psoriasis or persistent bowel symptoms as well.

Questions worth asking at your next appointment

• Which type of spondyloarthritis do I have?
• Is there evidence of active inflammation in my spine or other joints?
• What do my blood tests and scans show—and what can they not tell us?
• Which exercises should I focus on?
• How will we know whether my treatment is working?
• Do my eye, skin or bowel symptoms affect the choice of medicine?
• Are there medicines or vaccinations I need to discuss before starting treatment?
• Do I need any precautions because of spinal stiffness?

This information is general. Discuss your diagnosis, medicines and exercise plan with your own healthcare team.