Ankylosing spondylitis, also known as Bechterew’s disease, belongs to the group of spondyloarthropathies—that is, inflammatory diseases of the musculoskeletal system. The disease is more common in young men between the ages of 20 and 40. It primarily affects the spine and the junction with the pelvis, known as the sacroiliac joint. In some cases, symptoms may also occur in the knee joint and at the sites where tendons attach to bone.
As the disease progresses, the bones and joints are destroyed and broken down by inflammation, while new bony spurs form in other areas. These spurs serve no anatomical function and severely restrict the mobility of the affected person’s skeleton.
According to estimates, approximately 0.5 percent of people in Western Europe develop ankylosing spondylitis.
Ankylosing spondylitis is a chronic condition that progresses in flare-ups. With each flare-up, back pain and limitations in movement can worsen. Adhesions and stiffness occur in the joints and ligaments, but the heart, eyes, and other organs may also be affected by changes.
The following symptoms indicate ankylosing spondylitis:
- The main symptoms are deep-seated back pain, morning stiffness, and nighttime pain
- Additionally, the following symptoms frequently occur: hip, knee, and shoulder pain
- Heel pain
- Tennis elbow and tendon disorders
- Fatigue
- Weight loss
- Pain when sneezing or coughing
After years and several flare-ups, ankylosing spondylitis noticeably alters posture. The pelvis flattens, and the thoracic spine becomes increasingly curved, resulting in a hump. The body’s joints are then usually further restricted in their movement due to severe pain.
Significant complications may include changes affecting the eyes, heart, or kidneys, which require thorough evaluation by specialists. Otherwise, there is a risk of permanent damage to the affected organ systems.
The exact reasons why ankylosing spondylitis develops—and in whom—remain unclear. Genetics may play an important role, but autoimmune reactions are also suspected. However, the presence of HLA-B27 in the blood of those affected is also very striking. This is a surface protein that helps the immune system recognize pathogens and threats. In some cases, however, HLA-B27 triggers strong immune reactions that are suspected of causing inflammatory attacks on bones and joints. This ultimately leads to chronic inflammation of the spine and pelvis, known as ankylosing spondylitis. However, the specific pathogen that ultimately triggers this overreaction remains unknown.
To diagnose the condition, the patient’s cooperation during the medical history interview is very important. Characteristic back pain usually prompts the patient to seek medical attention. In addition, other signs point to ankylosing spondylitis:
- Lower back pain lasting more than three months
- Symptoms beginning before the age of 45
- Morning stiffness lasting longer than half an hour
- Improvement in back pain with movement, but not at rest
- Frequent nighttime awakenings in the second half of the night due to severe lower back pain
- Alternating pain in the buttocks.
To confirm the suspected diagnosis, the doctor uses various methods. One is the Mennell test, in which the leg is raised backward while the patient is lying on their stomach. In patients with ankylosing spondylitis, this causes pain in the sacral region. The Schober-Ott sign, on the other hand, helps assess the mobility of the spine. A patient with spondylitis will be unable to touch the floor with their fingertips when bending the body forward.
It is also helpful to measure inflammatory markers (e.g., CRP or erythrocyte sedimentation rate), perform MRI scans of the back, or test for rheumatic factors such as HLA-B27.
Treatment for ankylosing spondylitis is based on three main pillars:
- medications for pain and inflammation,
- Medications to suppress the immune system, and finally
- Exercise and diet.
Nonsteroidal anti-inflammatory drugs (NSAIDs) are generally considered the pain relievers of choice. However, since these can damage the stomach with long-term use, they are often prescribed in combination with medications that protect the stomach. During acute flare-ups, cortisone injections may also be used.
Physical therapy and light exercise have proven effective as adjuncts to medication. When it comes to diet, patients should avoid fat and excessive amounts of meat, as the arachidonic acids (= specific fatty acids) they contain promote inflammation.
Immunosuppression is used only when all other therapies have been exhausted without success. This is because a suppressed immune system always carries a higher risk of developing infections or cancer.
Ankylosing spondylitis is a chronic disease that progresses in episodes and develops over the course of many years. The disease is incurable with current treatments. However, its course and prognosis can be positively influenced. An active lifestyle is recommended, as is a healthy diet with plenty of fruits and vegetables. In addition to medically supervised pain management, patients should follow specialized exercise programs designed for them by both physical therapists and occupational therapists.
However, it is particularly important to attend follow-up examinations to assess changes in the skeleton. If complications arise in the cardiovascular system, eyes, or kidneys, vision, kidney function (measured by glomerular filtration rate = eGFR), and heart function (e.g., via ECG) should be regularly monitored by the respective specialist (ophthalmologist, nephrologist, cardiologist). In such cases, the prognosis can remain positive even with progressive ankylosing spondylitis, and the progression of the disease can be slowed.
What are the first symptoms of ankylosing spondylitis?
The first symptoms are often nonspecific and begin gradually before the age of 45. A typical symptom is deep-seated back pain in the lumbar spine and buttocks, which worsens at rest and improves with movement. A characteristic feature is morning stiffness in the joints and back that lasts longer than 30 minutes. Pain at the sites where tendons attach to bones, such as the Achilles tendon or the heel bone, can also occur early on.
How is ankylosing spondylitis diagnosed?
A combination of medical history, clinical examination, and imaging is crucial for an early diagnosis. Since X-rays are often still unremarkable in the early stages, magnetic resonance imaging (MRI) is the gold standard for detecting early sacroiliitis (inflammation of the sacroiliac joints). Laboratory test results, such as the detection of HLA-B27 and inflammatory markers, support the diagnosis. Classification criteria, such as those described in the MSD Manual, help to reliably classify axial spondyloarthritis, including ankylosing spondylitis.
What role does HLA-B27 play?
The HLA-B27 genetic marker is detectable in approximately 90 to 95 percent of patients with ankylosing spondylitis. However, it is not proof of the disease, as many healthy people also carry this marker. It is, however, considered a strong risk factor and indicator. In patients with ankylosing spondylitis who are HLA-B27-negative, the disease sometimes has a milder or more atypical course.
How does the disease progress, and what are syndesmophytes?
The course of the disease varies greatly from person to person and is usually episodic. Chronic inflammation at the edges of the vertebral bodies causes the body to attempt to repair the damage through new bone formation. This results in bony outgrowths, known as syndesmophytes, which connect the vertebrae to one another. Over time, this leads to ossification and stiffening of the spine (bamboo-stick spine), which often results in increased curvature (kyphosis) of the thoracic spine.
What treatment options are available?
Treatment is based on three pillars: exercise, medication, and education. Nonsteroidal anti-inflammatory drugs (NSAIDs) are often the treatment of choice to relieve pain and stiffness and reduce inflammation. If these are not sufficient or if disease activity is high, biologics (e.g., TNF inhibitors) are used, which specifically target the immune system. Sulfasalazine can also be helpful when large peripheral joints (e.g., hip, knee) are affected.
Why is physical therapy so important?
Regular physical therapy and independent exercise are essential for correcting posture and counteracting spinal stiffness. Targeted exercises strengthen the back muscles and maintain mobility. Sports such as Nordic walking or swimming are particularly recommended for people with ankylosing spondylitis. Organizations such as the German Ankylosing Spondylitis Association offer special group therapy programs for this purpose.
What comorbidities can occur?
In addition to affecting the skeleton, ankylosing spondylitis is a systemic disease. Uveitis (inflammation of the uvea) often occurs and requires immediate treatment by an ophthalmologist. Chronic inflammatory bowel diseases such as Crohn’s disease or ulcerative colitis, as well as psoriasis, are also associated with the condition. In addition, patients have an increased risk of osteoporosis, as the inflammation weakens the bones, even if bone growth is visible on the outside.
What is the life expectancy for ankylosing spondylitis?
Thanks to modern therapies and early diagnosis, life expectancy for ankylosing spondylitis is generally not reduced, or only slightly so, these days. The key is to control disease activity and prevent complications such as cardiovascular disease or severe vertebral fractures caused by osteoporosis and stiffness.
