What is ankylosing spondylitis (AS)?

Ankylosing spondylitis (AS) is an inflammatory condition that affects the joints in your spine. Spondylitis simply means inflammation of the spine.

As part of the body's reaction to inflammation, calcium is laid down where the ligaments attach to the bones that make up the spine (vertebrae). This reduces the flexibility of your back and causes new bone to grow at the sides of the vertebrae. Eventually the individual bones of the spine may link up (fuse). This is called ankylosis and can be seen on x-rays.

Ankylosing spondylitis typically starts in the joints between your spine and pelvis, but it may spread up your spine to your neck. It can sometimes affect other parts of the body, including your joints, tendons or eyes.

Ankylosing spondylitis varies from person to person – your symptoms might be so mild that you can almost forget you have the condition, but if they’re more serious it could have a big impact on your quality of life.

Ankylosing spondylitis is one of a group of conditions known as 'spondyloarthritis' (pronounced as spond-ee-lo-arthritis). These conditions share many of the same symptoms.

Related conditions

There are a number of conditions related to ankylosing spondylitis which have many similar symptoms:

  • Non-radiographic ankylosing spondylitis and undifferentiated spondyloarthritis (uSpA) have similar symptoms to ankylosing spondylitis but x-rays won't show the signs of damage to your joints. Sometimes people with these conditions are later diagnosed with ankylosing spondylitis.
  • Psoriatic spondyloarthritis is a form of psoriatic arthritis which occurs in association with the skin condition psoriasis.
  • Spondyloarthritis associated with inflammatory bowel disease (or enteropathic arthritis) is related to bowel conditions such as Crohn's disease or ulcerative colitis.
  • Reactive arthritis (which used to be known as Reiter's syndrome) is diagnosed when your arthritis is a reaction to an infection.
  • Enthesitis-related arthritis is the name used when children and teenagers develop arthritis of the entheses, the sites where tendons and ligaments attach to bone.

Some doctors use the terms spondarthritis, spondyloarthropathy, spondyloarthritides or seronegative spondyloarthritis. These terms all describe types of arthritis belonging to the same group of conditions as ankylosing spondylitis.

Who gets ankylosing spondylitis?

Ankylosing spondylitis can affect anyone, although it's most common in young men and most likely to start in your late teens or 20s.

The genes you inherit from your parents may make you more likely to develop AS, but the condition isn’t passed on directly. Most people with ankylosing spondylitis have a gene called HLA-B27, which can be detected by a blood test. This gene isn't the cause of ankylosing spondylitis but it does contribute to it.

Having this gene doesn’t mean you’ll definitely get AS, and the blood test isn't very useful in diagnosing the condition. Even in families where somebody's been diagnosed with ankylosing spondylitis there may be brothers or sisters who have the HLA-B27 gene but who don't have the condition.

Versus Arthritis has recently awarded grants for a project which will aim to understand how genes combine to cause AS and find out how alterations in gene regulators influence AS.

Symptoms

In the early stages, ankylosing spondylitis and the related conditions are likely to cause:

  • stiffness and pain in the lower back in the early morning which eases through the day or with exercise
  • pain in the sacroiliac joints (the joints where the base of your spine meets your pelvis), in the buttocks or the backs of your thighs.

Some people first notice problems after a muscle strain, so the condition is often mistaken for common backache. However, stiffness that lasts at least 30 minutes in the morning helps to distinguish ankylosing spondylitis from simple back pain. The symptoms may also occur after rest, or may wake you in the night.

You may also have neck, shoulder, hip or thigh pain, which is often worse if you've been inactive for a time, for example if you work at a computer. Some people have pain, stiffness and swelling in their knees or ankles. In psoriatic arthritis, the smaller joints of the hands and feet may be affected. For some people, especially children and teenagers, the first signs may be in their hip or knee rather than their back.

Inflammation can occur anywhere in the body where tendons attach to bone (this is called enthesitis), for example, at the elbow and heel. Inflammation comes and goes so the symptoms may vary over time.

The inflammation that causes these symptoms comes and goes, so the degree of pain can vary over time and from person to person. If the condition is mild and only affects the sacroiliac joints, it may go almost unnoticed, but if most of the spine is affected it can cause difficulty with activities that involve bending, twisting or turning.

Other possible symptoms include:

  • tenderness at the heel – This makes it uncomfortable to stand on a hard floor. Inflammation can occur at the back of your heel where the Achilles tendon meets the heel bone, or in the tendon in the arch of the foot which is known as plantar fasciitis.
  • pain and swelling in a finger or toe – When the whole digit is swollen it’s known as dactylitis.
  • tenderness at the base of your pelvis (ischium) – This makes sitting uncomfortable.
  • chest pain or a ‘strapped-in’ feeling that comes on gradually – If your spine is affected at chest level (the thoracic spine) it can affect movement at the joints between the ribs and the breastbone, which makes it difficult for you to take a deep breath. Your ribs may be very tender, and you may feel short of breath after even gentle activity. Coughing or sneezing may cause discomfort or pain.
  • inflammation of the eye (uveitis or iritis) – The first signs of this are usually a red (bloodshot), watery and painful eye, and it may become uncomfortable to look at bright lights. If this happens, or if you develop blurred vision, it's important to get medical help within 24–48 hours. The best place to go is an eye casualty department – this might not be at your local hospital. Your GP surgery, local A+E or your optician will know where the nearest eye casualty department is. Treatment is usually with steroid eye drops, which are generally very effective. Some people get repeated attacks of eye inflammation, but they're extremely unlikely to cause permanent damage if they're treated promptly.
  • inflammation of the bowel – People with ankylosing spondylitis can develop bowel problems known as inflammatory bowel disease (IBD) or colitis. Tell your doctor if you have diarrhoea for more than 2 weeks or begin to pass bloody or slimy stools. You might be referred to a bowel specialist (gastroenterologist). Symptoms of IBD can vary, but it can usually be treated successfully with medication. Sometimes treatments like non-steroidal anti-inflammatory drugs (NSAIDs) can make bowel problems worse, so you might be advised to stop taking them.
  • tiredness (fatigue) – This may be caused by the activity of the condition, anaemia or sometimes depression and frustration associated with the condition.

How will ankylosing spondylitis (AS) affect me?

Ankylosing spondylitis (AS) and the related conditions are quite variable and difficult to predict. They can cause a lot of pain, although treatment will help to ease this. You may have times when the symptoms become worse and other times when you find it easier to cope with the pain and stiffness. AS can make you feel generally unwell, lose weight or tire easily.

Most people with a spondyloarthritis have some stiffening in the spine, usually in the lower back. This can be painless and may not interfere with physical activity because the neck, hips, limbs and the upper part of your spine can remain quite mobile. However, if more of your spine stiffens or your knees or hips are affected, you may have more difficulty with mobility. Treatment can help prevent these mobility problems.

Very rarely, there may be complications affecting the heart, lungs and nervous system. The valves in the heart may leak, which can put it under more strain. And long-term inflammation and tissue scarring in the lungs can reduce rib movement, which means you can't take in a full breath. Very rarely, the top of the lungs may become scarred. Fewer than 1 in 100 people with ankylosing spondylitis have these problems, and they are even less common in other types of spondyloarthritis. Even so, if you smoke, it's extremely important to try to stop because smoking is likely to add to any heart or lung problems.

People with ankylosing spondylitis, especially those who've had the condition for a long time and whose vertebrae have fused, are at increased risk of spinal fractures following a trauma (for example, a fall or car accident). Spinal fractures can cause nerve damage, so it's important to tell any doctor treating you following trauma that you have ankylosing spondylitis, especially if you have new unexplained pain in your spine or new weakness or tingling in your arms or legs. The fracture may not show easily on x-rays, so you may need a magnetic resonance imaging (MRI) or computed tomography (CT) scan.

Some people with ankylosing spondylitis develop osteoporosis (thinning of the bones), and it's important that this is treated. Your doctor may suggest you have a bone density (DEXA) scan to check for this.

Diagnosis

Most back pain isn’t caused by ankylosing spondylitis (AS). However, the symptoms, especially in the early stages, can be very similar to more common back problems. Because of this, many people put up with the pain for some time before seeking help. When you first see your doctor, there may be little to show whether the problem is ankylosing spondylitis or some other, more common, back problem. Unfortunately, ankylosing spondylitis may even be misdiagnosed at first. Ankylosing spondylitis is normally diagnosed by a rheumatologist.

There's no specific test that will confirm you have ankylosing spondylitis, so diagnosis involves piecing together information from different sources, including:

  • the history of your condition (including whether pain and discomfort is waking you during the second half of the night)
  • a physical examination
  • blood tests, which may show inflammation.

What tests are there for ankylosing spondylitis?

A blood test can sometimes show if there's inflammation in the body. You'll probably have one or more of these tests:

  • C-reactive protein (CRP)
  • erythrocyte sedimentation rate (ESR)
  • plasma viscosity (PV).

These all test for inflammation, so they give similar information. Different laboratories use particular tests. Only 30–40% of people with ankylosing spondylitis have inflammation that can be picked up in a blood test, so in many cases these blood tests will be normal.

Another blood test can confirm whether you have the HLA-B27 gene. Most people with ankylosing spondylitis test positive for HLA-B27, but so do some people who don't have the condition. A positive test may point to AS but it won't confirm the diagnosis.

X-rays sometimes help to confirm the diagnosis, though they generally don't show anything unusual in the early stages. As the condition progresses new bone develops between the vertebrae, which will be visible in x-ray images. However, it may be several years before these signs show up in x-rays. Magnetic resonance imaging (MRI) scans may show changes in the spine or sacroiliac joints at an earlier stage of the disease.

You may need further tests, especially in the early stages. MRI scans may show the typical changes in your spine and at the sacroiliac joints at an earlier stage of the disease and before changes can be identified on x-rays.

Treatment

A number of treatments are available that can ease pain and stiffness, but exercise and close attention to your posture are just as important to keep the spine mobile and help you to live a normal life.

Drugs

Painkillers and NSAIDs

Painkillers (analgesics) and non-steroidal anti-inflammatory drugs (NSAIDs) are usually the first choice of treatment, and most people with ankylosing spondylitis will need to take these at times.

Painkillers such as paracetamol or co-codamol are often very helpful. They can be taken regularly and are particularly useful just before activity to keep your pain to a minimum. It's best not to wait until you're in severe pain before taking them. They don't need to be taken with a meal, though some water and a small snack are advised.

There's a wide range of NSAIDs that can reduce pain so you can get on with your daily activities and your exercise routine. You'll probably need to take these during bad patches, and some people may need them over a longer period. Some tablets are made in a slow-release formulation, which can help with night-time pain and morning stiffness. Some NSAIDs are also available as gels, which you can apply to the painful area.

Like all drugs, NSAIDs can sometimes have side-effects, but your doctor will take precautions to reduce the risk of these, for example by prescribing the lowest possible dose for the shortest possible period of time.

DMARDs

Drugs such as sulfasalazine and methotrexate can be helpful for arthritis in the joints of your arms or legs, although they're not usually effective for spinal symptoms. These disease-modifying anti-rheumatic drugs (DMARDs) are given to reduce damage to the joints rather than just controlling pain. They’re slow-acting so you won’t notice an immediate impact, but they can make a big difference to your symptoms over a period of time.

Biological therapies (anti-TNF drugs) are newer treatments that can be very effective for ankylosing spondylitis and non-radiographic axial spondyloarthritis. A number of anti-TNF drugs are currently available for these conditions – including etanercept, adalimumab, certolizumab pegol and golimumab. They can only be prescribed by a rheumatologist and are given as an injection under your skin, which you can learn to give yourself. Biological therapies aren’t suitable for everyone and can only be prescribed if your condition can’t be controlled with anti-inflammatory drugs and physiotherapy.

The effect of anti-TNF drugs is monitored, and you'll need to complete questionnaires regularly which assess how active your disease is and how well it's responding to treatment.

Steroids

Steroids can be used as a short-term treatment for flare-ups. They’re usually given as an injection into a swollen joint or as a slow-release injection into a muscle. They can also be used for painful tendons, for example at the heel, although they won't be repeated very often as this may lead to tendon weakness. Occasionally, you may be given a course of steroid tablets (prednisolone). While these treatments can be very effective at improving pain and stiffness, you may develop side-effects if you use them for long periods, for example, weight gain, bruising or thinning of the skin, high blood pressure, high blood sugar, infections or osteoporosis.

If you develop eye inflammation, it'll usually be treated with steroid eye drops. In more severe cases, steroids may be given as tablets or as an injection into the eye.

Bisphosphonates

Bisphosphonates are usually used to treat osteoporosis. It's been suggested they may also help the pain and stiffness of ankylosing spondylitis, although research so far hasn't confirmed this.

Managing your symptoms

Self-help measures, especially exercise, can help to minimise the long-term effects of ankylosing spondylitis (AS).

Exercise

Keeping as active as you can is really important if you have ankylosing spondylitis, or a related condition.

Aerobic exercise that makes you at least a little out of breath will improve your overall health and fitness. This type of exercise can help you to maintain a healthy weight for you, which is good for your back.

Strengthening the muscles in the back will provide better support to bones and joints, and this can reduce the amount of pain you’re in.

Doing exercise that puts the back through its natural range of movement and which also stretches the back muscles, will keep your back flexible.

If you are new to exercise, or if you haven’t exercised for a while, you should start slowly and gradually build up the amount you do. This means you should gradually increase how often you exercise, how long for and the effort you put in.

The key is to find something you enjoy and to keep doing it.

If you’re ever in intense pain and you find exercising difficult you may need to treat the pain first.

Being inactive for too long can make your back become stiff and so the sooner you can get back to being active the better.

Taking painkillers, such as paracetamol, and non-steroidal anti-inflammatory drugs, such as ibuprofen, before you exercise can help.

If you are ever finding it difficult to exercise, talk to a GP, or ask for a referral to a physiotherapist. If you’re a member of a gym, there may be personal trainers who can offer you expert advice. Make sure you tell them about your condition.

What is the best exercise for me if I have ankylosing spondylitis?

Pilates, yoga and T'ai chi may be useful for people with ankylosing spondylitis as these can help with posture, flexibility and core strength.

Swimming is also a fantastic all-round exercise, as it can work all your muscles and joints without jarring them. It allows you to improve strength, stamina and flexibility, which are all very important.

If you have limited neck movement, breaststroke and front crawl may become more difficult, and if you swim with your head up it can make neck pain worse.

One potential way around this could be to use a special mini snorkel designed for use in swimming pools. If you want to use one, talk to staff at your local pool first to check it’s allowed.

Be careful when you first use one of these snorkels and make sure you’re aware of your surroundings in the pool, for example other swimmers and the end of the lane.

Speak to your physiotherapist or a swimming instructor for advice if you have discomfort when swimming, as a different stroke or modification to your technique can often help.

As an alternative to swimming, your local swimming pool might run aerobic classes in shallow or deep water which you could try.

Contact sports such as rugby, hockey or basketball aren't generally recommended if your spine is very stiff as your joints and spine may be easily injured. But there are plenty of other activities that are suitable. If you enjoy competitive sports, volleyball and badminton are both low-impact.

We have examples of exercises you can do in your home every day to improve the flexibility and strength in and around your spine. This should greatly improve your symptoms. These exercises can be found at the back of the ankylosing spondylitis booklet.

Living with ankylosing spondylitis

Sex, pregnancy and children

Sex may be painful if you have inflammation in the sacroiliac joints or lumbar spine, and lack of mobility in the hips can be a problem. Try taking some painkillers beforehand and experimenting with different positions.

Ankylosing spondylitis (AS) can make you feel tired so it’s important that your partner understands how your condition affects you. Good communication is the key to preserving an active sex life and counselling can sometimes be helpful for both partners.

It’s fine to use the contraceptive pill if you have AS, but you should tell your doctor that you take it.

Read more about sex and arthritis.

Usually pregnancy doesn’t present any special problems for the mother or the baby, though the symptoms of ankylosing spondylitis may not ease during pregnancy, as they do in some other types of arthritis. If your spine is very stiff, it may not be possible to have an epidural during childbirth. If your condition makes it difficult to open your legs, it's a good idea to think ahead about the delivery and to discuss with the team at your antenatal appointments whether a Caesarean section might be better for you.

If you're thinking of starting a family, it's very important for both men and women to discuss any medications with your doctor beforehand so that your prescription can be changed if necessary. Some drugs such as methotrexate should normally be stopped several months before trying for a baby. Your doctor can also advise you on which medications are well tolerated during pregnancy and while breastfeeding.

Read more about pregnancy and arthritis.

Will my children develop AS?

If you have AS there's a small chance your children will also develop it. However, the way ankylosing spondylitis runs in families isn't straightforward. If you're thinking of having a baby and are concerned about this, discuss it with your specialist.

Parents with AS sometimes ask if their children should have the HLA-B27 test to see whether they might develop the condition in the future. This isn't recommended as there’s no way of knowing whether a child will develop AS even if they do have this gene.

Exercise

An illustration of someone standing with their back against the wall.

Stand against a wall

Standing with your heels and backside against a wall, push (but don’t tilt) your head back towards the wall. Hold for 5 seconds then relax. Repeat about 10 times if possible.

A diagram of someone stood with their legs apart and their hands on their hips.

Waist turn

Stand in an open space with your feet apart. Place your hands on your hips. Turn from the waist to look behind you. Keep your knees and feet facing the front. Hold for 5 seconds. Repeat to the other side, 5 times each side.

An illustration of someone laying down on their back with their legs bent.

Lay down, knees bent, breathe

Lying on your back, knees bent, feet flat on the ground:

(a) Put your hands on your ribs at the sides of your chest. Breathe in deeply through your nose and out through your mouth, pushing your ribs out against your hands as you breathe in. Repeat about 10 times. Remember, it’s as important to breathe out fully as it is to breathe in deeply.

(b) Put your hands on the upper part of the front of your chest. Breathe in deeply through your nose and then breathe out as far as you can through your mouth. Push your ribs up against your hands as you breathe in – again about 10 times. You can do this exercise at any time in a lying or sitting position.

A diagram of somone laying on their front with one arm in the air and their alternative leg lifts off the ground.

Superman

Lying on your front, looking straight ahead, hands by your sides (if necessary you can put a pillow under your chest to get comfortable).

Raise one leg off the ground keeping your knee straight, about 5 times for each leg. It helps to have the opposite arm stretched out in front of you.

A diagram of somone laying on their front with both arms by their side and their chest lifted off the ground.

Head and shoulder raise

Lying on your front, looking straight ahead, hands by your sides (if necessary you can put a pillow under your chest to get comfortable):

Raise your head and shoulders off the ground as high as you can – about 10 times.

A diagram of someone kneeling on the floor with one arm and one leg lifted off the ground.

Bird-dog

Kneeling on the floor on all fours, stretch alternate arms and legs out parallel with the floor and hold for 10 seconds. Lower and then repeat with the other arm and leg, 5 times each side.

Contact sports such as rugby, hockey or basketball aren't generally recommended if you have advanced disease as your joints and spine may be more easily injured, but there are plenty of other activities that are suitable. If you enjoy competitive sports, volleyball and badminton are both low-impact.

Pilates, yoga and t'ai chi may also be useful as these can help with posture and flexibility.

Swimming is one of the best forms of exercise because it uses all of your muscles and joints without jarring them. If you have limited neck movement, breaststroke and front crawl may become more difficult, and if you swim with your head up it can make neck pain worse. Using a snorkel can be helpful. Speak to a physiotherapist for advice if you have discomfort when swimming, as a different stroke or modification to your technique can often help. As an alternative to swimming, ask for a programme of exercises you can do in the pool.