What is axial SpA (AS)?

Discover the symptoms of axial SpA (AS) is and how it may affect you

Axial Spondyloarthritis (axial SpA) is an inflammatory arthritis where the main symptom is back pain

Axial spondyloarthritis is an umbrella term and it includes:

Ankylosing Spondylitis (AS)

Where changes to the sacroiliac joints or the spine can be seen on x-ray.

Non-radiographic axial spondyloarthritis

Where x-ray changes are not present but inflammation is visible on MRI or you have symptoms.

Around 7 in 10 people with non-radiographic axial spondyloarthritis have visible inflammation in the sacroiliac joints or the spine when an MRI of the back is carried out.

Around 3 in 10 may not have any inflammation visible on MRI despite symptoms of back pain. Some may never go on to develop visible  inflammation on MRI.  The reasons for this are still not well understood but may be due to the sensitivity of MRI.

Typical symptoms of axial SpA (AS) include:

  • Slow or gradual onset of back pain and stiffness over weeks or months, rather than hours or days
  • Early-morning stiffness and pain, wearing off or reducing during the day with exercise
  • Persistence for more than 3 months (as opposed to coming on in short attacks)
  • Feeling better after exercise and worse after rest
  • Weight loss, especially in the early stages
  • Fatigue or tiredness
  • Feeling feverish and experiencing night sweats

What happens?

It’s a painful, progressive form of inflammatory arthritis. It mainly affects the spine but can also affect other joints, tendons and ligaments.

Other areas such as the eyes and bowel can also sometimes be involved.

  1. Inflammation occurs at the site where ligaments or tendons attach to the bone. This is known as enthesis
  2. The inflammation is followed by some wearing away of the bone at the site of the attachment. This is known as enthesopathy
  3. As the inflammation reduces, healing takes place and new bone develops. Movement becomes restricted when bone replaces the elastic tissue of ligaments or tendons
  4. Repetition of this inflammatory process leads to further bone formation and the individual bones which make up your backbone (vertebrae) can fuse together

This short video explains the basics about axial SpA (AS)

This short video explains how axial SpA (AS) can affects areas of your body such as your chest, eyes and bowels

Read more

  • 220k

    Adults in the UK

    1 in 200 of the adult population in the UK have axial SpA (AS). That's twice as many as multiple sclerosis and Parkinson's disease.

  • 24

    Average age

    Axial SpA (AS) is a condition that affects young people. Symptoms start late teens to early twenties, with the average age of onset being 24.

  • 8.5

    Years to diagnosis

    The current average delay to diagnosis from when symptoms start is 8.5 years, by which irreversible damage to the spine may have occurred.

  • 59%

    Mental health

    59% of people with axial SpA report suffering mental health problems compared to 25% of those with musculoskeletal conditions overall.