What is Ankylosing Spondylitis?
Ankylosing spondylitis is long-term inflammation of the spine and the sacroiliac joints, with damage visible on X-ray. It causes back pain and stiffness that improve with movement and worsen with rest, typically beginning before the age of 45. Modern treatment controls the inflammation and, started early, largely prevents the spinal fusion the disease is named for.
Also called: AS, radiographic axial spondyloarthritis
Who gets Ankylosing Spondylitis?
Onset is usually between 20 and 40, and almost always before 45. It is more common in men, who also tend to have more spinal damage, though the disease is substantially under-diagnosed in women, whose symptoms are more often attributed to fibromyalgia or mechanical pain. Over 90 per cent of patients in most populations carry HLA-B27, although the great majority of B27-positive people never develop the disease. The average delay between first symptom and diagnosis remains five to eight years.
What are the symptoms of Ankylosing Spondylitis?
Not everyone has every symptom below, and having one does not confirm the diagnosis. These are the features that most often lead to assessment:
- Lower back and buttock pain lasting more than three months, beginning before the age of 45
- Morning stiffness lasting more than thirty minutes
- Pain that improves with exercise and worsens with rest — the reverse of mechanical back pain
- Waking in the second half of the night with pain, and needing to move about
- Alternating buttock pain, from one side to the other
- Heel pain, or pain at the ribs, chest wall and shoulders
- Reduced spinal movement, difficulty turning the head or a stooped posture in advanced disease
- Painful red eye with light sensitivity (acute anterior uveitis) in up to 40 per cent
- Fatigue
How is Ankylosing Spondylitis diagnosed?
The history does most of the work: inflammatory back pain has a specific pattern that mechanical back pain does not, and asking the right five questions identifies most cases.
X-rays of the sacroiliac joints show the changes that define ankylosing spondylitis, but they may take years to appear. MRI detects active inflammation of the sacroiliac joints far earlier, and is what allows diagnosis in the non-radiographic stage.
HLA-B27 and inflammatory markers support the picture. CRP is normal in a substantial minority despite active disease, so a normal result does not exclude it.
Spinal mobility measurements are recorded at diagnosis and repeated over time to track the disease objectively.
How is Ankylosing Spondylitis treated?
Exercise is not an adjunct here — it is a primary treatment, and the evidence for it is as strong as for any medicine. Daily spinal extension, mobility and postural work preserves movement and reduces pain, and stopping it reliably makes the disease worse.
Non-steroidal anti-inflammatories are first-line and are effective for many patients, taken regularly during active disease rather than only when pain is severe.
When they fail, biologics work well: TNF inhibitors and interleukin-17 inhibitors both substantially reduce inflammation and improve function, and JAK inhibitors are a further option. Conventional DMARDs such as methotrexate do not work for spinal disease, though they help if peripheral joints are also involved.
Smoking accelerates spinal damage and reduces treatment response, so stopping matters more here than in most rheumatic disease.
Living with Ankylosing Spondylitis
The image of inevitable, complete spinal fusion is out of date. With treatment started early, most patients keep good mobility and continue to work. Bone density is checked, since fracture risk rises even while the spine appears to stiffen. Any painful red eye needs same-day ophthalmology assessment. Patients with a fused spine need to inform anaesthetists and physiotherapists before any procedure.
When should you see a rheumatologist?
Back pain that began before 45, has lasted more than three months, and improves with movement rather than rest should be assessed by a rheumatologist — particularly with morning stiffness, night pain, heel pain, psoriasis, bowel inflammation or a previous painful red eye.
Common questions about Ankylosing Spondylitis
Is ankylosing spondylitis a disability?
It varies widely. Many patients treated early continue in full-time work with little limitation. Advanced disease with significant spinal fusion can limit movement substantially. Early diagnosis and consistent exercise are the strongest factors in how well someone does long-term.
If I am HLA-B27 positive, will I get ankylosing spondylitis?
Almost certainly not. HLA-B27 is common in the general population and the large majority of carriers never develop the disease. The test is useful alongside symptoms, not as a screening test on its own.
Why do my X-rays look normal if I have this condition?
X-ray changes take years to develop. MRI shows active inflammation of the sacroiliac joints much earlier. Disease with a normal X-ray but positive MRI is called non-radiographic axial spondyloarthritis and is treated the same way.
Does exercise really help, or will it damage my spine?
It helps, substantially, and it is one of the most effective parts of treatment. Daily mobility and extension exercise preserves posture and reduces pain. Stopping exercise reliably makes the condition worse.
Will my spine definitely fuse?
No. Complete fusion is now much less common than it once was, because inflammation can be suppressed effectively. The earlier treatment starts, the less structural damage occurs.
This page is general information to support a consultation. It is not a diagnosis, and it does not replace an assessment by a doctor who has examined you.