Spinal Surgery for Ankylosing Spondylitis

Reviewed by: HU Medical Review Board | Last reviewed: June 2022 | Last updated: July 2022

Ankylosing spondylitis (AS) primarily affects the spine and sacroiliac joints, causing pain and stiffness, and it can progress to cause fused joints. Treatment for AS usually includes a combination of medications and physical therapy. While most people with AS don’t need surgery, in certain cases surgery may be necessary.1

How ankylosing spondylitis affects the spine

AS causes chronic inflammation in the vertebral joints and in the points where tendons and ligaments attach to the joints, called entheses. This chronic inflammation wears away at the bone of the joints. As the body works to replace the lost bone, it can create excess bone, leading to a fusing of the joint. The entheses and ligaments may also become calcified, called syndesmophytes. As the condition develops and the spine becomes more immobilized by the formation of bone in the joints, the spine can take on the appearance of bamboo on x-rays and is referred to as “bamboo spine.” The presence of bamboo spine increases a person’s risk of fractures in the vertebrae.2-4

AS can cause complications to the spine including spinal fracture, kyphosis, and stenosis. Spinal fractures, or breaks in the vertebrae, can range from mild to severe, with fractures in the cervical (neck) vertebrae being the most dangerous.5 Kyphosis is an outward curvature of the spine, which can cause a hunched or rounded back. This can cause a forward-stooped posture and in certain cases, can impact a person’s ability to fully inflate their lungs.6 Spinal stenosis is a narrowing of the spinal column. Spinal stenosis may affect the space where the spinal cord is (in the middle of the spinal column), the space where the nerves come out from the spinal cord to the rest of the body, or the space between the vertebrae.

Spinal stenosis can cause pain in the back or arms and legs. It may also cause a numbness or weakness of the arms or legs. A severe type of spinal stenosis is called cauda equina syndrome, which can lead to a loss of control of the bowels or bladder.7,8

Reasons why spinal surgery may be needed in ankylosing spondylitis

Spinal surgery may be necessary in certain cases of AS, such as1,9:

  • When the spine has become deformed in a fixed position that causes significant functional limitation, impacting the person’s ability to engage in daily activities
  • When the spine is unstable due to fractures and at risk of nerve damage
  • When the spine is creating a nerve problem, called a neurologic deficit, which may cause severe pain, numbness, or weakness

Types of spinal surgery for ankylosing spondylitis

The type of spinal surgery is based on the needs of the individual patient, such as if they have severe, unrelenting pain due to nerve damage or if they have kyphosis causing a deformity of the spine and making daily activities difficult or impossible. Some of the surgical procedures that may be used in people with AS include1,9:

  • Osteotomy
  • Spinal fusion instrumentation
  • Spinal decompression

In an osteotomy, the bone is cut to shorten, lengthen, or change its alignment. This may be used to correct a deformity, such as kyphosis. An osteotomy can help correct a person’s posture, but it does not fully restore the individual’s mobility and flexibility.1,9

A spinal fusion instrumentation stabilizes the spine and may be used in people with spinal fractures or if significant bone has been removed during an osteotomy. Using instrumentation such as screws, rods, bars, and/or wires, the surgeon fuses two or more vertebrae together. These fused joints will not allow for movement of that part of the spine, but the procedure is used to fix an unstable spine.1,9

Spinal decompression is used when nerves are being pinched due to excess bone tissue or fractures. The most common type of spinal decompression surgery is a laminectomy, in which the lamina of the vertebrae is removed to relieve pressure on the nerves.1,9

By providing your email address, you are agreeing to our privacy policy.