Ankylosing spondylitis is a type of arthritis that largely affects the joints and ligaments in your spine. Magnetic resonance imaging (MRI) is one of the earliest ways to detect and diagnose ankylosing spondylitis (AS).
Ankylosing spondylitis is a type of arthritis that largely affects the joints and ligaments in your spine. Magnetic resonance imaging (MRI) is one of the earliest ways to detect and diagnose ankylosing spondylitis (AS).

Magnetic resonance imaging (MRI) is one of the earliest ways to detect and diagnose ankylosing spondylitis (AS). An early diagnosis can help prevent later structural changes to your spine that could severely impair your body’s ability to function.  

MRI has even helped advance our understanding of AS. It has helped researchers pinpoint regions where ligaments attach to bones — called entheses — as areas where inflammatory cells can invade and potentially alter your bone marrow.

What is ankylosing spondylitis? 

Ankylosing spondylitis is a type of arthritis that largely affects the joints and ligaments in your spine. 

In some cases, the vertebrae in your lower spine will fuse, causing severe stiffness and pain. Other people will experience only occasional episodes of mild back pain. In either case, there’s no cure. 

AS can affect other joints, including those in your: 

  • Pelvis 
  • Ribs
  • Shoulders
  • Knees
  • Ankles
  • Heels

Who gets ankylosing spondylitis? 

In around 80% of cases, you’ll start to feel AS symptoms before 30. Only 5% of patients are over 45. The condition is also twice as common in men than women. 

There’s also one genetic link to AS: a gene called HLA-B27. If you have a family history of AS, you likely have this gene, and your doctor may order a blood test to confirm.

People with the HLA-B27 gene tend to develop the disease around 25 years of age, while those without it show symptoms closer to 28. It’s important to keep in mind that not everyone with HLA-B27 will develop AS. 

What are the symptoms of ankylosing spondylitis?

The main symptom of AS is lower back pain caused by inflammation. Still, there are other symptoms that you may experience:

If you have AS, there’s a good chance you have other conditions or symptoms that will help your doctor pinpoint this difficult-to-diagnose condition. These include: 

People who have one or more of these conditions and AS tend to have worse symptoms overall. We need more research to understand why these specific conditions are connected to AS. 

One hint is that Iritis, Crohn’s disease, and ulcerative colitis also involve inflammation. This is a possible link to the inflammatory back pain of AS. 

The condition tends to cause lethargy and can often get in the way of your everyday life. The pain and loss of flexibility can make it difficult for people to continue their jobs and maintain their mental health

If you have AS, it’s important to seek the help you need when you need it, including therapy and counseling services. 

Is an MRI better than X-rays for diagnosing ankylosing spondylitis?  

A formal diagnosis of ankylosing spondylitis used to require evidence of severe changes to your sacroiliac joints through X-rays. These joints act as shock absorbers for your spine and transfer force from your lower body into your upper body. The problem is this damage can take up to ten years to become visible, leading to seven to 10 years of delayed diagnosis. 

MRIs use powerful magnets to create images of each section of a body part, such as a joint. A computer then combines these slices to create a three-dimensional model.  

An MRI can help your doctor detect inflammation in your lower (axial) spine and your sacroiliac joints. MRI-confirmed inflammation in these regions, combined with other risk factors and symptoms, is a good indication you have ankylosing spondylitis.  

An MRI can detect symptomatic inflammatory changes many years earlier than X-rays. It’s by far the better imaging method for your earliest possible diagnosis. Computed tomography (CT) scans are also much better than X-rays at detecting these early signs of inflammation. 

What are other ways to diagnose ankylosing spondylitis?

Another essential part of diagnosing AS is a detailed physical exam. This will include an inspection of your joints and flexibility. You may also be asked to breathe deeply to check for any stiffness or inflammation in your ribs.

Since persistent lower back pain is the most common symptom, your doctor will want to know specific details to determine if it’s caused by inflammation or mechanical problems. The pain needs to continue for at least three months before this disease is considered a possibility. 

Unlike mechanical causes, inflammatory AS back pain tends to be: 

  • Worse when you first wake up 
  • Worse when you sit still for a long time
  • Better when you stretch and exercise 
  • So severe in the second half of the night that the pain can wake you up
  • Accompanied by alternating pain in your left and right buttocks

You can help your doctor with this diagnosis by keeping careful track of your back pain details.


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What are treatment options for ankylosing spondylitis? 

Treatment for this disease focuses on relieving your symptoms and slowing the damage caused by AS. The three main treatment techniques include: 

  • Medications: The most commonly recommended medication is over-the-counter anti-inflammatories, like ibuprofen. Corticosteroids can be directly injected into problematic joints, and newer biological medications can interfere with your immune system’s inflammation response.
  • Physical Therapy: Essential for correcting your posture — both while awake and asleep — and figuring out the most appropriate exercise regime for your body. 
  • Surgery: Used to repair severe joint damage caused by the disease but must be considered on a case-by-case basis.  

When should you see a doctor? 

Part of the difficulty with catching ankylosing spondylitis early is that few young people seek medical attention for back pain. Regardless of your age, you should seek medical help if your back pain lasts for more than three months or if you believe it’s caused by persistent inflammation. 

An early diagnosis can help prevent some long-term effects, so it’s better to see your doctor as soon as you notice problematic symptoms.

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Medically Reviewed on 3/29/2022

Johns Hopkins Arthritis Center: "Ankylosing Spondylitis."

National Institutes of Health: "Ankylosing Spondylitis."

Stanford Healthcare: "Diagnosis."

The Journal of the Canadian Chiropractic Association: "Ankylosing spondylitis: recent breakthroughs in diagnosis and treatment."

Wong, M., Sinkler, M.A., Kiel, J. StatPearls: "Anatomy, Abdomen, and Pelvis, Sacroiliac Joint." StatPearls Publishing, 2021