Ankylosing Spondylitis and Bamboo Spine: What Is the Relationship?

Updated on 2024-05-16 14:57:35 0 0

By Lindsay Curtis

Medically reviewed by Anita C. Chandrasekaran, MD

Ankylosing spondylitis (AS) is a chronic form of inflammatory arthritis that primarily affects the spine, causing back pain and stiffness. In later stages of the disease, AS can cause the bones of the spine to fuse together into one long, rigid bone. This is known as “bamboo spine.”

Read on to learn more about the connection between ankylosing spondylitis and bamboo spine, including risk factors and treatments.

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Connection Between Ankylosing Spondylitis and Bamboo Spine

Ankylosing spondylitis (AS) is a form of autoimmune arthritis characterized by long-term inflammation of the spine and sacroiliac joints that connect the base of the spine to the pelvis.1 As the disease progresses, inflammation may spread to other areas of the body and cause pain and stiffness in other joints, including the neck, shoulders, ribs, hips, and heels.

Common symptoms of AS include:2

Back pain and stiffness
Mild fever
Loss of appetite
General discomfort

In advanced AS, chronic inflammation can lead to new bone formation in the spine, called ankylosis. This can ultimately cause the spinal vertebrae to fuse in a fixed, rigid position. AS-related bone fusion typically begins at the sacroiliac joints and progresses up the spine, from the lumbar spine (lower back) to the cervical spine (neck). This is referred to as bamboo spine because the spine resembles a bamboo stem on imaging scans.

Advanced ankylosing spondylitis and bamboo spine are also associated with the following:

Limited mobility and flexibility: The fused, rigid spine can make it hard to engage in daily activities, such as putting on shoes.
Kyphosis: This is a rounded upper back, or hunchbacked posture.
Increased risk of fracture: People with spinal rigidity have 4 times the risk of fractures.3
Cauda equina syndrome: This occurs when nerve roots in the lower back are compressed, reducing mobility and sensation in the lower body. Research suggests that bamboo spine may stiffen the outer layer of tissue that protects the spinal cord (dura mater), causing nerve root damage.4
Difficulty breathing: Joints between the rib and spine may become inflamed and painful, which can restrict chest movement and make breathing difficult.5

Risks

The exact cause of ankylosing spondylitis is not yet fully understood. About 90% of people with AS have the HLA-B27 gene, but many people with the gene do not develop the disease.2 This suggests that a combination of genetic and environmental factors increases the risk of AS.

AS is associated with chronic inflammation in the spine, which causes the spinal joints and surrounding soft tissues—including intervertebral discs, ligaments, and tendons—to calcify and harden over time.6 Bamboo spine develops due to this calcification.

Not everyone with AS will develop bamboo spine. Getting diagnosed and following your treatment regimen can help manage the pain and inflammation to reduce the risk of bamboo spine.

Treatment and Management of Ankylosing Spondylitis With Bamboo Spine

There is no cure for ankylosing spondylitis, but treatments can reduce symptoms and help slow the progression of the disease. Ankylosing spondylitis is most often treated with a combination of physical therapy and medications. Healthy lifestyle choices are also recommended, including a nutritious diet, regular exercise, practicing good posture, and not smoking.

Ankylosing spondylitis medications are designed to reduce pain and inflammation and reduce the risk of spinal fusion. Common AS medications include:2

Nonsteroidal anti-inflammatory drugs (NSAIDs)
Biologics
Corticosteroids
Janus kinase (JAK) inhibitors
Monoclonal antibodies
Methotrexate

Surgery may be considered if ankylosing spondylitis has progressed and the spinal vertebrae have fused together. Surgery for people with AS is rare and is generally only recommended for people with severe pain and spinal deformity.

Surgical procedures to treat bamboo spine include:78

Osteotomy: This is a procedure to reduce spinal deformity and improve spinal stability and mobility. The surgeon will cut and realign spinal vertebrae during the procedure to correct deformities such as kyphosis.
Laminectomy: This is a decompression procedure that removes a portion of the spinal vertebrae (lamina) to relieve pressure on the spinal cord and nerves.
Spinal fusion: This procedure is used to correct spinal deformity and provide stability to the spinal column. Rods and/or screws may be inserted to fuse spinal vertebrae into a better position.

The type of surgery your healthcare provider recommends will depend on your symptoms, spinal deformity severity, and overall health.

Summary

Ankylosing spondylitis (AS) is a progressive inflammatory arthritis that primarily affects the spine and sacroiliac joints. Over time, long-term inflammation of the spine may cause the vertebrae to fuse together into a long, rigid bone that resembles a stalk of bamboo. This is known as bamboo spine.

Not everyone who has AS will develop bamboo spine. Early diagnosis and proper treatment with medications, lifestyle changes, and regular exercise can help slow AS progression.

Sources

Spondylitis Association of America. Ankylosing spondylitis overview.

National Institute of Arthritis and Musculoskeletal and Skin Diseases. Ankylosing spondylitis.

Zhu W, He X, Cheng K, et al. Ankylosing spondylitis: etiology, pathogenesis, and treatments. Bone Res. 2019;7:22. doi:10.1038/s41413-019-0057-8

Tang C, Moser FG, Reveille J, et al. Cauda equina syndrome in ankylosing spondylitis: challenges in diagnosis, management, and pathogenesis. J Rheumatol. 2019;46(12):1582-1588. doi:10.3899/jrheum.181259

MedlinePlus. Ankylosing spondylitis.

Talotta R, Rucci F, Scaglione F. Calcium physiology, metabolism and supplementation: a glance at patients with ankylosing spondylitis. Reumatologia. 2020;58(5):297-311. doi:10.5114/reum.2020.100112

Veritas Health. Ankylosing spondylitis surgery.

UpToDate. Patient education: axial spondyloarthritis, including ankylosing spondylitis (beyond the basics).