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Ankylosing Spondylitis (AS)

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What is ankylosing spondylitis?

Ankylosing spondylitis is a chronic inflammatory arthritis of the spine and the sacroiliac joints. It belongs to a family of conditions called spondyloarthritis, and is also known as axial spondyloarthritis or, in parts of Europe, Bechterew’s disease. It is strongly linked to a gene called HLA-B27. Unlike the wear-and-tear arthritis of older age, it is driven by the immune system, and it usually begins in early adulthood, most often in men.

The inflammation causes pain and stiffness, and over many years it can lay down new bone across the joints of the spine, gradually stiffening it and, in advanced cases, fusing it. It is a lifelong condition, but a treatable one: modern medical treatment has changed its outlook considerably, and most people with it never need spine surgery.

What does ankylosing spondylitis feel like?

The hallmark of ankylosing spondylitis is inflammatory back pain, which behaves differently from ordinary mechanical back pain. Rather than improving with rest, it is typically worse after inactivity and improves with movement or exercise. Symptoms usually begin gradually before the age of 40 and may include prolonged morning stiffness, pain that wakes a person during the second half of the night, and deep pain in the lower back or buttocks arising from the sacroiliac joints.

Over time, the stiffness can spread up the spine, reducing how far a person can bend and turn and, where the joints between the ribs and spine are involved, how far the chest can expand. Fatigue is common. Because it is a whole-body inflammatory disease, it can also involve the eyes (a painful red eye, from uveitis), the bowel, and the skin, all worth mentioning to the rheumatologist.

One important point as the disease advances: a spine that has fused becomes rigid and often thin-boned, which makes it brittle. A fused spine can fracture from a fall, and those fractures are serious. This is covered in the surgery section, and it is why any new, severe, or changed back or neck pain after even a minor knock should be evaluated promptly.

How is ankylosing spondylitis diagnosed?

Ankylosing spondylitis is diagnosed and managed by a rheumatologist, and the diagnosis is built from the pattern of symptoms, examination, blood tests, and imaging together, because no single test settles it. The HLA-B27 gene is often present and supports the diagnosis, but it does not confirm it on its own, since many people carry the gene without ever developing the disease. Imaging is central: an X-ray, or earlier in the disease an MRI, of the sacroiliac joints shows the tell-tale inflammation and later changes. One well-known problem is delay: because the early pain is easily mistaken for an ordinary bad back, the diagnosis is often made years after the symptoms begin, which is why the inflammatory pattern above is worth recognising.

How is ankylosing spondylitis treated?

Ankylosing spondylitis is treated medically, and for most people that treatment now works well. The mainstays are:

  • Exercise and physiotherapy: this is the cornerstone, not an optional extra. Regular, specific exercise to keep the spine mobile and upright does more than almost anything else to protect long-term function.
  • Anti-inflammatory medication: non-steroidal anti-inflammatory drugs, taken regularly, are the first-line medication and control symptoms in many people.
  • Biologic drugs: where inflammation continues despite the above, biologic medications that block specific parts of the immune response, the TNF inhibitors and IL-17 inhibitors, have transformed the disease over the past two decades, controlling inflammation that older drugs could not. The disease-modifying tablets used in other forms of arthritis do not work for the spine in AS.

This medical treatment, led by a rheumatologist, is what controls the disease, and it is why most people with AS never need an operation. Surgery has a role, but only for specific structural problems the disease can cause, which is the subject of the next section.

When does ankylosing spondylitis need spine surgery?

Surgery does not treat the inflammation of AS, and it is a last resort, reserved for two specific structural problems the disease can cause. Both are areas of specialised spine surgery.

  • A fixed forward-stooped spine: in advanced disease the spine can fuse into a fixed forward curve, leaving a person unable to stand straight or look ahead, and in severe cases affecting breathing and digestion. A spinal osteotomy, cutting and realigning the fused spine, can restore an upright posture and a level gaze, and can markedly improve quality of life in the right patient.
  • A spinal fracture: a fused AS spine is rigid and often thin-boned, so it fractures easily, sometimes after only minor trauma, and those fractures tend to run through the whole thickness of the spine, making them highly unstable and dangerous. They are also easily missed, because the pain can be mistaken for the disease itself. A fracture in an AS spine is a specialist emergency that usually needs surgical stabilisation, and it should never be managed as ordinary back pain.

Sometimes the two overlap, and a fracture in a badly deformed spine is stabilised and realigned in the same operation. These are complex procedures that belong with a surgeon experienced in spinal deformity.

What we see at Spine Connection

Ankylosing spondylitis is a rheumatology condition first, and the medical treatment that controls it belongs with a rheumatologist. We work alongside that, not instead of it. The cases we can genuinely help are the structural ones: a spine that has fused into a disabling stoop, or a fracture in a rigid AS spine. Both are specialised work.

Dr. Chaidej Sasomboon, who reviews this page, is an orthopedic spine surgeon and Deputy Medical Director at Bangkok International Hospital, with fellowship training in complex and deformity spine surgery and published work on the balance between the spine and the pelvis, which is exactly the judgement that deformity correction in AS demands.

Some patients ask us about stem cell or regenerative therapy to help modulate the overactive immune system and repair the joint arthritis that comes with AS. It’s important to say that this is still experimental for AS and the evidence is developing. It’s not a substitute for the proven traditional rheumatology treatments.

Frequently Asked Questions

It is an immune-mediated inflammatory disease, which is why it behaves so differently from wear-and-tear arthritis. The immune system drives inflammation in the spine and the sacroiliac joints rather than the joints simply wearing out. It is strongly linked to a gene called HLA-B27, though many people carry that gene and never develop the disease. It is treated by a rheumatologist.

Inflammatory back pain comes on gradually, usually before the age of 40. It is worse with rest and often wakes people in the second half of the night. Prolonged morning stiffness is typical. Most tellingly, it improves with movement and exercise rather than being eased by rest – the opposite of mechanical back pain. That pattern is the main reason to ask about ankylosing spondylitis.

No. Degenerative conditions are wear-related and become more common with age. Ankylosing spondylitis is inflammatory, driven by the immune system, and it usually begins in early adulthood rather than later life. Over many years the inflammation can lay down new bone across the joints of the spine, gradually stiffening and in advanced cases fusing it, but the underlying process is inflammation, not wear.

By a rheumatologist, from the pattern of symptoms, examination, blood tests and imaging together, because no single test settles it. An X-ray, or earlier in the disease an MRI, of the sacroiliac joints shows the tell-tale inflammation. The HLA-B27 gene supports the diagnosis but does not confirm it alone. Delay is a well-known problem, because the early pain is easily mistaken for an ordinary bad back.

Most people never need spine surgery. The disease is controlled medically, and modern treatment works well for the majority. Surgery has a role for two specific structural problems it can cause: a spine that has fused into a fixed forward stoop, where a realignment operation can restore upright posture, and a fracture in a rigid spine, which needs specialist stabilisation.

A spine that has fused becomes rigid and is often thin-boned, which makes it brittle. It can fracture from a fall that would barely bruise anyone else, and those fractures tend to run through the whole thickness of the spine, making them highly unstable. They are also easily missed, because the pain gets mistaken for the disease itself. Any new, severe or changed back or neck pain after even a minor knock should be checked promptly.

We would rather be straight than sell a hope. Stem cell and regenerative therapy for the inflammation of ankylosing spondylitis is still experimental, the evidence is developing, and it is not a substitute for the rheumatology treatment that actually controls the disease. Anti-inflammatory medication and, where needed, biologic drugs are what have changed the outlook for this condition over the past two decades.

Considering surgery for AS deformity or a fracture?

If ankylosing spondylitis has left you with a fixed, stooped spine, or you have had a fall and are worried about a fracture in a rigid spine, that is exactly the kind of case worth having reviewed by a spine deformity specialist. Our surgeons in Thailand and Germany can review your imaging and history and give you a clear, honest opinion on whether surgery would help and what it would involve.

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Sources

  1. Ankylosing Spondylitis. StatPearls (updated 2023). (A chronic inflammatory disease linked to HLA-B27, usually starting before 40 and more common in men; first-line treatment is long-term NSAIDs, then TNF inhibitors.) (https://www.ncbi.nlm.nih.gov/books/NBK470173/)
  2. HLA-B27 Syndromes. StatPearls (updated 2023). (2019 American College of Rheumatology guidance: continuous NSAIDs first-line, then TNF and IL-17 inhibitors; conventional disease-modifying drugs are ineffective for axial disease; complications include osteoporosis and vertebral fractures.) (https://www.ncbi.nlm.nih.gov/books/NBK551523/)
  3. Bechterew's Disease and the Risk of Spinal Fractures: a systematic review. 2025. (A rigid, ankylosed spine is prone to unstable fractures, often after low-energy trauma, frequently extending through all three columns with a high risk of spinal cord injury.) (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12681504/)
  4. Spinal deformity correction in ankylosing spondylitis. Journal review. (A vertebral osteotomy can re-establish spinal and pelvic balance and improve pain, posture, and even breathing and digestion in symptomatic deformity.) (https://pmc.ncbi.nlm.nih.gov/articles/PMC9062901/)
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