Ankylosing spondylitis

This is the medical name for a chronic form of arthritis which affects the joints of the spine. The muscles and ligaments are also affected.

It is a type of inflammation of the spine which affects more men than women and in some cases, can lead to a long term disability. What is unusual is that this condition develops in young people, especially teenagers whereas many forms of arthritis affect middle aged and older people.

There is no cure at the moment for ankylosing spondylitis but there are methods for keeping it control. These ease the symptoms, keep the spinal column erect and allow you to lead a normal life.

Ankylosing spondylitis becomes less active over time but it needs to be regulated on a daily basis.

Around 200,000 people have been diagnosed with ankylosing spondylitis in the UK.

(Source: NHS Choices/ankylosing spondylitis)

It is discussed as follows in this section:

  • Who is more prone to ankylosing spondylitis?
  • How does ankylosing spondylitis occur?
  • Causes of ankylosing spondylitis
  • Symptoms of ankylosing spondylitis
  • Diagnosis of ankylosing spondylitis
  • Tests for ankylosing spondylitis
  • Treatment for ankylosing spondylitis
  • Managing ankylosing spondylitis
  • Complications of ankylosing spondylitis

Who is more prone to ankylosing spondylitis?

Ankylosing spondylitis occurs in teenagers and young adults up to the age of 35. It affects three times as many men as women.

How does ankylosing spondylitis occur?

Want to know more about the spine first? Here is a brief overview of the anatomy of the spinal column.


This is a bony structure which runs from the skull at one end to the pelvis at the end.

The spine is comprised of 24 individual vertebrae (bones) which are stacked in a column upon each other. There are soft pads between each of these vertebrae which act as shock absorbers and help cushion the spine.

Each single vertebra contains two sets of ‘facet joints’which in conjunction with the soft pads enables the spine to flex and stretch. These vertebrae are supported by tough bands of tissue called ‘ligaments’ and together with the muscles of the spine, ensure that the back is strong and durable.

At the base of the spine there are two bones called the ‘sacroiliac joints’which are found on either side of the spinal column. These allow weight to be transferred from the upper body to the lower body i.e. pelvis.

What can go wrong?

This form of arthritis occurs due to pain, stiffness and swelling in areas of the spinal column. The joints of the spine or vertebrae become inflamed but once this dies down the spine becomes stiffer and less flexible.

After the inflammation, new bone replaces the tendons and ligaments between the vertebrae and eventually causes the spinal column to fuse together. The spine becomes stiff and causes pain around the base of the spine, neck and buttocks.

The vertebrae, ligaments and sacroiliac joints become inflamed which results in pain, stiffness and reduced mobility.

Causes of ankylosing spondylitis

It is difficult to determine the cause or causes of ankylosing spondylitis. There are aspects of this form of arthritis which are still not fully understood so it is hard to pinpoint an exact cause.

But researchers have identified a gene called the ‘HLA-B27’gene which is linked to this condition.

The HLA-B27 gene

This gene is carried by the majority of people with ankylosing spondylitis. It increases the risk of ankylosing spondylitis so check to see if anyone in your family has this condition.

If they have then there is a strong chance that you will get this condition but it is by no means automatic. In other words, having this gene does not mean that you will experience this condition.

There is a test for this gene but we need to be careful when interpreting the results for example, there are various subtypes of this gene so that must be taken into account.

Other forms of arthritis

There are several forms of arthritis which can trigger ankylosing spondylitis (AS). These diseases, for example reactive arthritis, occur before AS or at the same time which means double the pain, stiffness and inflammation. Not to mention the worry and stress.

Children with arthritis can go on to develop ankylosing spondylitis in their teens or adulthood.

Symptoms of ankylosing spondylitis

These vary from one person to another but generally, they take a long period of time to develop. This is usually a period of several months but there are cases in which it has been several years before the symptoms appeared.

These symptoms are intermittent or worsen over time.

They include:

    • Inflammation of the joints
    • Back pain and/or buttock pain
    • Stiffness of the spine
    • Fatigue
    • Swelling around the point where the tendons or ligaments attach to the bone (known as ‘enthesitis’).

You may develop some or all of these symptoms. These are discussed in a little more detail.

Inflammation of the joints

This causes inflammation (or arthritis) in the joints of your spine but can also affect your knee, hip and other joints. The affected joint (or joints) are stiff, swollen and sore to the touch.

Back pain

Back pain and/or buttock pain are common symptoms of this condition. Your back is stiff first thing in the morning but eases once you start to move. It improves with exercise but seizes up again once you rest.

You may experience pain in the buttocks which occurs on one side or the other.

Stiffness of the spine

You may wake up in the middle of the night with a spine which is painful and stiff. Plus it will feel very stiff when you wake although this eases after half an hour or so.


Extreme tiredness is a common feature of ankylosing spondylitis. You will have a lack of energy and find it difficult to do your normal daily tasks. This may be accompanied by periods of feeling off-colour and unable to motivate yourself.


This is a medical term for a painful swelling which develops where a bone is connected to a ligament or tendon. Examples of this include the ends of the ribs, top of the shin and under the heel.

What is the progression of this condition?

This is often very painful to start with although this will ease with treatment. You can expect to have phases or ‘flare ups’where the symptoms will be at their worst before dying down. Alternately these symptoms may be mild and come and go over a period of time.

The lower part of the back becomes stiff after a period of time but then disappears without any complications. If you develop a stiff back then you can still be fairly active although you will need to factor in some rest periods.

Diagnosis of ankylosing spondylitis

A problem with this is that back pain is a very common medical complaint so your symptoms may be mistaken for any number of back problems.

However, back pain as part of ankylosing spondylitis is very different to other types of back pain so it may be diagnosed quickly. This back pain is characterised by the fact that it worsens during rest and often wakes the sufferer up in the latter part of the night.

Your GP will discuss your symptoms with you. He or she will ask you about your family history as there is a genetic link with this condition. You will also be asked about your medical history.

He/she will examine your spine and any other affected areas. This is then followed by referral for tests and a consultation with a specialist or rheumatologist.

Tests for ankylosing spondylitis

These are the same series of tests which are used in the diagnosis of other types of arthritis such as rheumatoid arthritis. They include blood tests, X-rays, ultrasound scan and an MRI scan.

Blood tests

This is a very common diagnostic tool which most of us have undergone at some time in our lives. It is quick and simple and gives a clear indication of the state of your health.

There are a series of blood tests which check protein levels, red blood cell counts and the presence of antibodies in your blood. These include a C-reactive protein (CRP) test and a full blood count (FBC).

These tests indicate how much inflammation you have in your back and spinal column.


An X-ray of your spine, in particular your lower back is a useful tool for spotting any degeneration in the spine. It can also detect any fusing together of the vertebrae.

Ultrasound scan

This type of scan uses a probe and sound waves which transmit images inside the body via a monitor. Your GP or specialist can use this device to check the condition of your bones and tissues and see if there are any signs of an inflammation.

This test works in the same way as an ultrasound scan during pregnancy.

MRI scan

This stands for ‘Magnetic Resonance Imaging’and uses powerful magnetic and radio waves to obtain detailed, 3D images inside the body.

This is useful at spotting signs of ankylosing spondylitis in your sacroiliac joints or other areas of your spine which cannot be detected by X-rays.

What needs to be borne in mind with these tests is that ankylosing spondylitis takes a long time, sometimes several years to develop. So it may not show up on any of these tests.

This is why it is difficult to diagnose.

What will happen is that your specialist will use a set of criteria to confirm or reject a diagnosis. There are three sets of criteria which refer to inflammation in your sacroiliac joints –known as ‘sacroiliitis’. You need to fulfil at least one of these criteria to be confirmed as having ankylosing spondylitis.

These tests will also show if you have the HLA-B27 gene. This is an indicator of ankylosing spondylitis but not a confirmed diagnosis.

Treatment for ankylosing spondylitis

The treatment for this is the same as for many other types of arthritis. It is not a cure but is designed to relieve the symptoms so that you are able to function in as normal a way as possible.

The aim behind any treatment is to keep the spine as flexible and moveable as possible. If this is combined with exercise, physiotherapy and an awareness of your posture then it will enable you to retain your independence.

Your GP and rheumatologist (a specialist) will devise a course of treatment for you. This will include medication, exercise and physiotherapy.

Medication will include painkillers such as Paracetamol: non-steroidal anti-inflmmatory drugs (NSAID’s), e.g. Ibuprofen: a tumour necrosis factor (TNF) drug which reduces inflammation in your joints: steroid injections to reduce any pain and stiffness: and anti-rheumatic drugs such as ‘Sulfasalazine’ which also ease inflamed joints.

If you want to know more these and other forms of treatment then visit our treatment for arthritis section.

Managing ankylosing spondylitis

This means self-help measures such as diet and exercise and physiotherapy which will allow you to live a relatively normal life.

But these must be adhered to on a daily basis to reduce the risk of complications and long term effects.

This means ensuring that you take your medication as and when instructed. Using ice packs to ease any swelling: exercise such as stretches or swimming: maintaining a good posture to avoid any strain on your back and stopping smoking (if you are a smoker).

If you are overweight then try and lose a few pounds as excess body fat puts a strain upon your joints which includes your spine.

Other issues include using mobility aids, claiming benefits such as Disability Living Allowance, pain relief and employment.

Find out more in our living with arthritis section.

Complications of ankylosing spondylitis

This condition tends to settle down the older you get. But it is a complex form of arthritis with a risk of complications which impact upon your day to day life.

These include:

  • Cardiovascular disease, e.g. heart attack or stroke
  • Uveitis: inflammation of the iris (eye infection)
  • Fracture of the spine
  • Osteoporosis (brittle bones)
  • Fixed posture and limited mobility
  • Cauda equina syndrome (compressed nerves in your spine)

Your rheumatologist or GP will discuss these risks with you and recommend a few lifestyle changes if necessary. These include stopping smoking, eating healthily and monitoring your weight.

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