Ankylosing Spondylitis: Symptoms, Causes and Treatment

OVERVIEW

Ankylosing spondylitis is a type of seronegative spondyloarthritis, meaning blood tests for rheumatoid factor are usually negative. It is a long-term inflammatory arthritis that most often affects the sacroiliac joints (where the spine meets the pelvis) and the spine.

It is different from rheumatoid arthritis, which usually affects small joints on both sides of the body in a symmetrical pattern.

When ankylosing spondylitis affects joints outside the spine, it tends to involve a few large joints, often in the legs, and on one side more than the other.

It also causes inflammation where tendons and ligaments attach to bone, called enthesitis. Over years, inflammation in the spine can cause new bone to form, and in severe cases the vertebrae fuse, leaving the spine rigid.

Ankylosing Spondylitis Causes

The exact cause isn’t known, but several factors raise the risk:

Age: symptoms usually start in the late teens to 20s, and most people develop symptoms before age 45
Sex: both men and women get it, but it is diagnosed more often in men
Genetic factors: genes play an important role. Most people with the disease carry the HLA-B27 gene, but many people with this gene never develop it
Family history: having a relative with the disease raises your risk
Related conditions: Crohn’s disease, ulcerative colitis, and psoriasis are linked to a higher chance of developing it
Environmental factors: environmental triggers also appear to play a role, and smoking makes the disease worse

Ankylosing Spondylitis Symptoms

Lower back pain: the most common symptom is long-lasting pain and stiffness in the lower back, hips, or buttocks, usually starting in young adulthood. The pain is often worse at night and can wake people from sleep.
Morning stiffness: stiffness is typically worst in the morning and often lasts more than 30 minutes, easing as you move around.
Pain improvement: unlike mechanical back pain, the pain tends to get worse with rest or long periods of sitting and better with exercise, movement, or a hot shower.
Peripheral arthritis: some people have pain and swelling in other joints, such as the hips, knees, ankles, or shoulders.
Enthesitis: inflammation where tendons and ligaments attach to bone, often at the heel (Achilles tendon), the sole of the foot, or around the ribs.
Axial skeleton involvement: the normal curve of the lower back may flatten, and if the rib joints are affected, chest expansion and deep breathing can become harder.
Other symptoms: fatigue, loss of appetite, and weight loss. Symptoms often come in flares with calmer periods in between.

Extra Articular Features of Ankylosing Spondylitis:

Eye disease: anterior uveitis, an inflammation inside the eye, is the most common feature outside the joints. It causes eye pain, redness, light sensitivity, and blurred vision and needs prompt treatment by an eye doctor.
Heart involvement: in long-standing disease, inflammation can affect the aorta and aortic valve, causing aortic valve leakage (regurgitation) or heart rhythm problems such as heart block.
Lung involvement: stiffness of the chest wall can limit breathing. Less often, scarring (fibrosis) develops in the upper parts of the lungs.
Nervous system involvement: a fused, brittle spine is more easily fractured, which can injure the spinal cord. Rarely, cauda equina syndrome develops in long-standing disease.
Bowel and skin: inflammatory bowel disease and psoriasis occur more often in people with ankylosing spondylitis.

Tests for Ankylosing Spondylitis

Ankylosing spondylitis usually develops slowly, with symptoms that come and go. Bone erosions and fusion (ankylosis) develop over many years. It can also cause osteoporosis of bones, raising the risk of spine fractures. No single test diagnoses ankylosing spondylitis, so doctors combine your history, an exam, imaging, and blood tests.
X-ray of sacroiliac joints: X-rays can show erosions, irregular joint margins, and later narrowing and fusion of the sacroiliac joints. These changes can lag years behind symptoms.
X-ray of the spine (side view): in established disease, X-rays may show "squaring" of the vertebrae and bony bridges between vertebrae called syndesmophytes. In advanced disease, these bridges and fused ligaments create the classic "bamboo spine."
MRI spine and sacroiliac joints: MRI can show active inflammation before changes appear on X-ray, so it helps detect the disease early.
DEXA scan: this bone density scan checks for osteoporosis, which is common in ankylosing spondylitis and increases the risk of fractures.
Erythrocyte sedimentation rate (ESR): this blood test measures how quickly red blood cells settle in a tube. It is often raised during active inflammation, but a high ESR is not specific and cannot confirm the disease on its own.
C-reactive protein (CRP): CRP is another marker of inflammation. It is often raised when the disease is active and helps doctors track how active it is, but a normal result does not rule the disease out.
Autoantibody levels: tests such as rheumatoid factor (RF), ANA, and anti-CCP (ACPA) are usually negative in ankylosing spondylitis. They help separate it from rheumatoid arthritis. By contrast, osteoarthritis is a different, wear-related joint disease that doesn’t cause these antibodies.
HLA-B27 test: this blood test checks for the gene linked to the disease. A positive result supports the diagnosis but does not confirm it, because many people who carry HLA-B27 never develop the disease.

What Complications Can Develop If Test For Ankylosing Spondylitis Is Not Done On Time?

Uveitis (inflammation of the eye): the most common complication outside the joints. Without treatment, it can damage vision.
Bone fractures: bones can become thin and the stiff spine more brittle, raising the risk of vertebral fractures, even after minor falls.
Heart problems: inflammation can affect the aorta and aortic valve, and people with the disease have a higher risk of heart disease.
Lung problems: chest wall stiffness can reduce lung capacity. Upper-lobe lung fibrosis is a rare complication.
Bowel problems: inflammatory bowel disease, such as Crohn’s disease or ulcerative colitis, is more common in people with ankylosing spondylitis and can cause abdominal pain and diarrhea.

How to Diagnose Ankylosing Spondylitis?

Your doctor will take a careful history and ask questions like:

when did your symptoms start?
which joints were involved first?
was one joint affected or several?
how long have you had symptoms?
what makes the pain better or worse?
is the disease limiting your mobility?
do you have eye, skin, or bowel symptoms, or a family history of the disease?

After taking your history, your doctor will examine your spine, pelvis, heels, and chest. They may check how far you can bend and how much your chest expands when you breathe deeply. The following investigations may be ordered:

Complete blood count (CBC) and inflammation markers (ESR and CRP)
HLA-B27 blood test
X-rays and MRI of the sacroiliac joints and spine, to look for inflammatory disease of the spine.

Ankylosing Spondylitis Treatment

There is no cure, but treatment can control symptoms and help slow the disease. Your rheumatologist will tailor treatment to you.

Nonsteroidal anti-inflammatory drugs: NSAIDs are usually the first medicine tried because they relieve pain and stiffness. Use them only as your doctor directs, since long-term use can affect the stomach, kidneys, and heart.
TNF inhibitors: these biologic medicines are a common next step when NSAIDs don’t control the disease. They can quickly reduce spinal and joint symptoms.
IL-17 inhibitors and JAK inhibitors: these are other options for active disease, including when TNF inhibitors don’t work.
Disease-modifying antirheumatic drugs: DMARDs such as sulfasalazine or methotrexate may help arthritis in the arms and legs, but they don’t work for spine disease.
Corticosteroids: steroid injections into an inflamed joint may help. Long-term steroid pills are generally avoided.
Other biologics: medicines that work in rheumatoid arthritis, such as anakinra, tocilizumab, and rituximab, have not shown clear benefit in ankylosing spondylitis and are not standard treatments.
Surgery: joint replacement may help when a hip is badly damaged. Rarely, surgery is used to straighten the spine or repair fractures.

Conservative Management of Disease

Exercise is the cornerstone of management. Daily stretching and back extension exercises help, and low-impact activity such as swimming or water exercise is a good choice
Physical therapy helps relieve symptoms and keep the spine flexible
Good posture helps prevent the spine from fusing in a bent-forward position
Staying physically active
Quitting smoking, which worsens the disease and blunts the effect of treatment
Maintaining a healthy weight

When to Seek Medical Help?

See a doctor if you have back pain and stiffness that lasts more than three months, is worse in the morning or after rest, and improves with movement.

Get care right away for sudden eye pain, redness, or blurred vision, or for new back pain after a fall if you have the disease.

Your doctor will explain the condition and your treatment options. Treatment can’t cure the disease, but with treatment most people lead full, productive lives.