Home / Conditions / Ankylosing spondylitis
Back pain that is worse after rest and better after moving is not ordinary back pain. It is the opposite pattern — and it is the reason this condition is typically recognised years after it started.
Ankylosing spondylitis is an inflammatory arthritis affecting the spine and the large joints. Inflammation starts most often at the sacroiliac joints, where the base of the spine meets the pelvis, then works upward.
Where inflammation persists, the body lays down new bone as it heals. Over years that can form bony bridges between vertebrae, gradually fusing them. A fused spine is stiff and, importantly, brittle — which matters more than most descriptions of this condition let on.
It affects men more often than women, and inflammation can occur elsewhere too — most commonly in the eyes.
You may also see it called axial spondyloarthritis. That is the current umbrella term for inflammatory disease of the spine and sacroiliac joints, and ankylosing spondylitis is the form in which changes are visible on X-ray. Where inflammation is present on MRI but the X-ray is still normal — often the case in the early years — it is called non-radiographic axial spondyloarthritis. The symptoms and the treatment are largely the same; the difference is what the imaging has reached yet.
The middle panel is where treatment matters most. Inflammation settles at the corners of the vertebrae, where the disc attaches to bone. It is painful, it is what the medication targets, and at this stage nothing has been permanently lost.
The right-hand panel is what happens if that inflammation continues unchecked for long enough. New bone laid down during repeated healing bridges one vertebra to the next, the disc spaces close, and the segment stops moving. The result is sometimes called a bamboo spine.
This progression is not a timetable. It takes years where it happens at all, many people never reach the right-hand panel, and modern treatment has made that outcome considerably less common than it once was.
This is the most useful thing on this page. Ordinary mechanical back pain and inflammatory back pain behave differently, and knowing which you have changes who you should see.
| Mechanical back pain | Inflammatory back pain | |
|---|---|---|
| After rest | Better | Worse |
| After exercise | Worse | Better |
| Morning stiffness | Brief, under 30 minutes | Over 30 minutes |
| At night | Usually settles | Often wakes you, especially the second half of the night |
| Age at onset | Any | Typically under 45 |
| Onset | Often sudden, after a strain | Gradual, over months |
If you are under 45, your back pain has been going on for more than three months, and it is better when you move around, that combination is worth mentioning to a doctor specifically.
Back pain in a young adult is overwhelmingly likely to be mechanical, so that is what it gets treated as — with rest, painkillers and physiotherapy. The pain improves somewhat, returns, and the cycle repeats.
Meanwhile the features that distinguish it are ones nobody asks about: how long the morning stiffness lasts, whether exercise helps or hurts, whether pain wakes you in the early hours. Delays of several years between first symptoms and diagnosis are common, and they matter because treatment works better before fusion has occurred.
A painful red eye with blurred vision or light sensitivity needs same-day assessment. Inflammation inside the eye is a recognised part of this condition and is treatable — but not if it waits.
This is the part most descriptions of ankylosing spondylitis leave out. A fused spine breaks more easily than a normal one, and it can break after an injury that would not trouble anyone else — a trip, a low fall, a minor car accident.
These fractures are unstable and can injure the spinal cord. They are also easily missed, because a fused spine looks abnormal on imaging anyway.
Get assessed the same day if, after any injury, you have:
Say that you have ankylosing spondylitis. It changes what is looked for and how.
Diagnosis combines the pattern of symptoms with examination and imaging. There is no single test.
A normal X-ray does not exclude it. That single fact accounts for a good share of the diagnostic delay — someone is X-rayed early, told their spine is normal, and the question is dropped for another five years.
There is no cure, and it would be dishonest to imply one. What there is, is effective control — and the outlook has changed substantially with the newer medications.
In most back conditions exercise is supportive. In this one it is central. Regular stretching, movement through the full range, and posture work maintain mobility and slow the loss of it. Stopping moving because it hurts makes this condition worse in a way it does not with mechanical back pain.
Usually first-line, and often markedly effective — a strong response is itself suggestive of the diagnosis. Taken regularly rather than only when the pain is bad.
Where anti-inflammatories are not enough, targeted biologic treatments can substantially control the disease. These are prescribed and monitored by a rheumatologist, and they are the reason the outlook is better now than it was two decades ago.
Surgery does not treat the disease. It addresses what the disease has caused:
Almost nobody arrives at a doctor saying they think they have ankylosing spondylitis. They arrive with back pain that has not gone away — which is why a spine clinic is where this condition is most often first suspected, and where those years of delay are either shortened or added to.
Recognising it is the highest-value thing that happens in that appointment, and it depends on asking the right questions: how long the morning stiffness lasts, whether exercise helps or hurts, whether pain wakes you in the early hours. Those are not questions that get asked if the working assumption is a strained back.
This is the assessment that changes the next ten years. It is also not either/or — a disc problem in someone with AS is still a disc problem, and inflammatory and mechanical pain frequently coexist. Telling which is causing what is a spine assessment, and it determines whether you need medication, surgery, or both.
MRI of the sacroiliac joints shows inflammation years before an X-ray shows anything. Knowing to request it — and knowing what normal looks like on a spine that is partly fused — is the difference between a diagnosis now and a diagnosis in five years.
Fracture of a fused spine, fixed deformity from years of fusion, pressure on the spinal cord or nerve roots, and hip joints damaged enough to need replacing. These are what actually disable people with this condition, and they are treated here rather than referred onwards.
The medications that control the inflammation — particularly the biologics — are prescribed and monitored by a rheumatologist. That is a collaboration rather than a handover: the medical and the structural sides of this condition run in parallel for decades, and each needs someone looking after it.
Dr Mathew Tung covers the neurosurgical spine work, and Dr Lim Heng Hing the orthopaedic spine and joint side, from the same clinic — so the assessment, the imaging and whatever follows happen in one place.
Yes. X-rays show established changes and are frequently normal in the early years. MRI shows active inflammation in the sacroiliac joints much sooner, which is why it is the more useful test when the condition is suspected.
That is characteristic of inflammatory back pain and the opposite of mechanical back pain. It is one of the most useful things you can tell a doctor, and one of the things least often asked about.
Not necessarily. The course varies widely, and modern treatment substantially reduces both symptoms and progression. Staying active matters more here than in almost any other back condition.
Get checked the same day, even if the pain seems minor. A fused spine fractures more easily than a normal one, those fractures are unstable, and they are easily missed. Tell whoever sees you that you have AS.
No. It is a genetic marker carried by most people with the condition, but also by many people who never develop it. It supports a diagnosis alongside symptoms and imaging; it does not make one on its own.
No. Bring any imaging and blood results, and a note of how long your morning stiffness lasts, whether exercise helps, and whether pain wakes you at night.
Lower back pain · Back pain · Neck pain · Hip pain · Slipped disc · Scoliosis · Spine surgery
If your back pain is better with movement and worse after rest, that is worth saying out loud to someone. It changes what gets looked for.
