Ankylosing spondylitis (AS) can lead to spinal complications such as spinal fusion and spinal stenosis. Medication and physical therapy are often enough to manage pain, but some people may need surgery.

AS is an inflammatory type of arthritis that primarily affects your spine, causing chronic pain and stiffness along your back.

AS develops when the sacroiliac joints in your spine become inflamed. Over time, the inflammation spreads to joints between your vertebrae until it affects your entire spine.

Here’s what to know about the possible ways AS can affect your spine and the related treatment options you may consider discussing with a doctor.

Symptoms of AS

Symptoms of AS most commonly develop between ages 15 and 30. You might experience back pain and stiffness that progressively worsens and tends to improve after physical activity.

As this type of arthritis progresses, you may also experience symptoms in other affected joints, such as your shoulders, hips, and knees. Up to 30% of people with AS may also develop eye pain and inflammation, which may cause sensitivity to light.

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When AS affects the vertebrae of your spine, these bones may grow or fuse together. This complication, known as spinal fusion, may increase pain, reduce mobility, and increase your risk of bone fractures along your spine.


Anti-inflammatory medications and injections may treat the inflammation that leads to spinal fusion in AS. A doctor will also likely recommend physical therapy to help with posture and overall mobility. In rare cases, you may need surgery to correct severe spinal fusion.

Spinal stenosis is a condition that causes narrowing and compression of the spaces within your spine. This may result in lower back pain; numbness and weakness in your legs, ankles, and feet; and a burning sensation that may extend from your buttocks to your legs.

While anyone may develop spinal stenosis, various types of arthritis, including AS, may increase your risk.


Treatment for spinal stenosis primarily consists of anti-inflammatory and pain medications, as well as nonsurgical treatments such as brace supports and physical therapy. In severe cases, if the condition affects your mobility, you may need surgery.

An infection in a bone or joint causes osteomyelitis, a type of bone inflammation. While it is rare, osteomyelitis is a serious condition that may spread through your bloodstream to other areas of your body.

If osteomyelitis affects your spine — a condition called vertebral osteomyelitis — you may experience back pain and stiffness along with fever, muscle spasms, and unintentional weight loss.


In addition to AS treatments, a doctor may prescribe antibiotics to help treat the bone infection. Depending on the severity of the infection, they may prescribe these in oral (tablet) or intravenous (IV) form. You may also need hospitalization.

Spinal fusion from AS increases your risk of spinal fractures due to osteoporosis, a condition that weakens your bones. The longer you have AS, the greater your long-term risk of broken bones.

In a 2017 review of spinal fractures in AS, researchers found that most fractures developed as a result of ground-level falls or seemingly minor injuries. The average age of those affected was 63.4 years.


You may be able to prevent spinal fractures from AS with medications doctors use to treat osteoporosis. If you do experience a spinal fracture, your treatment options may depend on the location and extent of the broken bone. Treatment may involve surgery or nonsurgical options such as braces.

Cauda equina syndrome (CES) is a rare but severe AS complication that causes nerve compression at the base of your spine. This may cause pain and numbness along your lower back, weakness in your legs, and urinary or bowel incontinence.


After diagnosing CES, a doctor may recommend emergency surgery within 48 hours of symptom onset to prevent permanent motor and sensory changes. This will also help treat urinary or bowel incontinence, with the possible addition of medications to address these symptoms.

There’s currently no cure for AS. Early detection and treatment are especially critical to help prevent spinal fusion and other complications. Consider seeing a doctor for an evaluation for AS if you:

  • experience chronic back pain and stiffness
  • are experiencing ongoing back pain that’s worse after resting or may be spreading to your low back and hips
  • have a family history of AS
  • have a personal history of other inflammatory conditions that may increase your risk of AS, such as psoriasis, Crohn’s disease, or ulcerative colitis

Once a doctor gives you an AS diagnosis, it’s important to follow your treatment plan. This will likely involve a combination of medications to reduce inflammation and pain. Healthcare professionals may also suggest exercises that can help you feel better while improving your mobility, posture, and flexibility.

AS causes inflammation along your spine, which can lead to long-term pain and reduced mobility. Without proper management of the disease, the most common complication is spinal fusion, though there are other spine-related issues to consider as well. Treating your AS can help lower your risk of developing some of these complications.

Consider talking with a doctor about these spinal complications, and visit a doctor if you’re experiencing worsening pain and stiffness.