Ankylosing spondylitis (AS) is a chronic form of arthritis that can lead to a complication known as “bamboo spine”. This results in widespread fusing of the bones in the spine.

Bamboo spine is less flexible, more fragile, and has a different shape than a healthy spine.

It does not happen to everyone with AS.

Doctors can see bamboo spine on an X-ray because the spinal vertebrae appear square and close together.

Treatment for bamboo spine depends on each individual case and does not always involve surgery.

AS is a form of inflammatory arthritis. It mostly affects the spine. After many years with the condition, some people experience widespread ankylosis, or fusing of the bones.

At this stage, the spinal vertebrae no longer move independently. The spine is rigid and loses flexibility. This is what some call “bamboo spine.”

As a result of these changes, people experience restriction of movement and greater vulnerability to fracture of the spinal bones.

How does ankylosis cause bamboo spine?

AS causes inflammation of the entheses, which is the tissue that connects tendons and ligaments to bone.

After an inflammatory flare, the body tries to heal. Over time, this natural process of repeated repair leads to scarring and the formation of extra bone.

Ultimately, this leads to the fusion of the bones, which is called ankylosis.

The spine is at risk for fracture because the spine is less flexible, and the bone created during the fusion process is weak.

Fractures of the spine occur in 10% of people with AS. The condition is one cause of osteoporosis.

Every person with AS has a unique experience with its progression. People who achieve an early diagnosis and start treatment may slow or prevent advanced complications.

Many people with AS never experience bamboo spine, as newer biologic medications have made it easier to manage the condition and prevent it from progressing.

A healthy spine is made up of several bones that form a chain. That chain provides stability and moves with the body because of spinal disks and elastic ligaments that allow for flexibility.

Although a spine without AS looks straight from the back, there is an S-curve when viewed from the side. This offers optimal mobility and support.

In bamboo spine, that chain of bones fuses together to make one long segment of bone. This causes changes in how the spine works, making it:

  • Less flexible. Bamboo spine does not support the same range of movement as a healthy spine.
  • More fragile. Bone weakness can lead to a greater risk of fracture.
  • Different shape. The spine may have less of a curve and begin to resemble a stalk of bamboo.

These differences in the spine lead to many possible complications of AS, such as back, hip, and shoulder pain.

Treatment of AS at all stages is focused on reducing inflammation and improving quality of life. Medication, exercise, physical therapy, stress reduction, and complementary therapies can all form part of a treatment plan.

Most people with AS never require surgery to manage the condition, especially with recent advances in medication prescribed in earlier stages. Surgery may be indicated to replace the hip joint or to correct kyphosis (rounding of the upper back).

Many people with bamboo spine do not require surgery, despite the widespread ankylosis.

There are medical case reports of people with mild to moderate back pain as the result of bamboo spine whose symptoms were relieved with physiotherapy and anti-inflammatory medication alone.

Surgery

In some cases, doctors may recommend surgery for bamboo spine, especially when the ankylosis is extensive or if it’s impacting a person’s quality of life.

There are three surgical procedures that doctors can perform for AS that may be appropriate for someone with widespread ankylosis.

  • Spinal osteotomy. The surgeon removes and repositions portions of the spinal bone in order to correct curvature and help regain stability. Spinal osteotomy is an umbrella term that includes a wide range of surgeries to realign the spine and improve quality of life.
  • Laminectomy. The surgeon removes parts of the spinal vertebrae (or lamina) to relieve pressure on the spinal cord and nerve roots. This can help to reduce pain.
  • Total hip replacement. The surgeon removes the hip joint and replaces it with a prosthesis. Hip replacement is for people whose hip joint has been damaged by AS.

For some people, treatment may include a combination of different surgical techniques in order to get the best outcome.

Below are some commonly asked questions about ankylosing spondylitis (AS) and bamboo spine.

Is bamboo spine reversible?

In bamboo spine, the vertebrae of the spine become fused together, resulting in reduced flexibility and mobility of the spine. Unfortunately, this fusion is irreversible. However, treatment for the condition can help relieve symptoms and manage pain.

What are the early signs of bamboo spine?

Bamboo sign is a radiographic finding of ankylosing spondylitis (AS), where there is significant fusion of the spinal bones. However, it is usually seen in advanced cases and takes a long time to diagnose.

Ultimately, progressive back stiffness is the main sign of bamboo spine.

What are the three most common symptoms of ankylosing spondylitis?

The symptoms of ankylosing spondylitis (AS) usually develop slowly over several months or years. They include:

  1. back pain and stiffness
  2. inflammation of the joints, such as in your hips and knees
  3. enthesitis, which is painful inflammation where a bone is joined to a tendon or ligament

Bamboo spine is one complication of ankylosing spondylitis, where spinal bones fuse together. Early detection of and treatment for AS can slow or prevent bamboo spine.

Those who live with bamboo spine may have access to a variety of surgical and nonsurgical treatments. These treatments can help reduce pain and inflammation, and improve quality of life.