Spondyloarthritis (SpA) refers to a family of closely related diseases that share common features – chief among them being inflammatory arthritis in the spine and other joints. Spondyloarthritis often begins in young people, with symptoms usually starting before age 45.
Over 3.2 million adults in the U.S. have a form of SpA, making it more common than rheumatoid arthritis (RA), multiple sclerosis (MS), and amyotrophic lateral sclerosis (ALS), combined.
These conditions are currently grouped into two overlapping categories:
Axial spondyloarthritis, which is characterized by inflammatory pain and arthritis in the spine and hips.
Peripheral spondyloarthritis, characterized by inflammatory pain and arthritis in peripheral joints and tendons other than the spine.
A person may have both axial and peripheral symptoms. The predominant symptoms (whether they are axial or peripheral) will determine the category, and the specific diagnosis.
A hallmark symptom of axial spondyloarthritis (axSpA) is inflammatory back pain, frequently characterized by a dull ache felt deep in the lower back, or buttocks. It is associated with inflammation of the sacroiliac (SI) joints, which are the joints linking the lowest part of the spine to the pelvis.
Inflammatory back pain usually begins before age 45, develops gradually, persists longer than three months, improves with physical activity but not rest, and can cause stiffness in the morning that lasts 30 minutes or longer. Though the lower back is usually impacted first, in some people inflammatory pain can start in the neck, or other areas. Other joints and organs can also become involved, including the hips, shoulders, eyes (iritis), gut (inflammatory bowel disease), and skin (psoriasis).
AxSpA is a broad category that includes people with and without characteristic bone changes or fusion in the spine. Doctors further classify adults as having one of two types of axSpA:
Radiographic axSpA, more commonly called ankylosing spondylitis, in which bone changes or fusing in the spine can be seen on x-ray.
Non-radiographic axSpA, without characteristic bone changes or fusing seen on x-ray.
To learn more about the experiences of people living with axSpA, please visit our interactive map.
In ankylosing spondylitis (AS) inflammation in the spine leads to changes that are visible on x-ray.
Over time, inflammation can lead to changes in the bones including ankylosis – new bone formation – causing sections of the spine to fuse in a fixed, immobile position. AS can also impact other areas of the body such as the neck, hips, ribs, heels, and other joints.
Not all people with axSpA will have bone changes that are visible on x-rays. When other signs and symptoms of axSpA are present, but spinal changes are not visible on x-ray, the diagnosis is non-radiographic axial spondyloarthritis (nr-axSpA). AS and nr-axSpA are thus part of the same axSpA disease spectrum and present with many of the same symptoms. The main difference is that those with nr-axSpA don’t show bone changes on x-rays, although inflammation can be spotted with the help of MRI. Some people with nr-axSpA progress to developing AS, although many do not.
Peripheral spondyloarthritis (pSpA) is characterized by inflammation and pain in joints and/or tendons primarily located outside the spine. Commonly involved sites include joints in the hands, wrists, elbows, shoulders, knees, ankles, and feet. Inflammation of the tendons can occur in the fingers or toes (dactylitis) or where tendons and ligaments attach to bone (enthesitis). Other organs can also become involved, including the eyes (iritis), gut (inflammatory bowel disease), and skin (psoriasis).
PSpA encompasses a number of distinct, though closely related conditions, including psoriatic arthritis, enteropathic arthritis, reactive arthritis, and undifferentiated arthritis.
Psoriatic arthritis (PsA) frequently causes inflammation, pain, and swelling in the small joints of the hands and feet. Other joints including the wrists, knees, and ankles can also become involved. Most people with PsA will have a skin rash called psoriasis, which causes scaly patches. In most cases the psoriasis will precede the arthritis. Some people will have a “sausage digit” with a toe or finger that swells between the joints and around the joints – this is called dactylitis. A portion of people with PsA also have pain and stiffness in the spine.
In addition to inflammatory back and/or joint pain, inflammation of the intestine, which includes the bowel, is a predominant feature of enteropathic arthritis (EnA). Symptoms may include chronic diarrhea, abdominal pain, weight loss, and/or blood in the stool. The most common types of inflammatory bowel diseases are Crohn’s, ulcerative colitis, and undifferentiated colitis.
In reactive arthritis (ReA) an infection in the intestine or urinary tract usually occurs before inflammation develops in the joints. As such, it is thought to occur as a reaction to an infection. ReA can cause inflammation and pain in the joints, skin, eyes, bladder, genitals, and mucus membranes. Infrequently it can also impact the spine. ReA tends to follow a limited course, with symptoms typically subsiding in three to 12 months. The condition does tend to recur, however, and some people with ReA will develop a chronic form of arthritis.
People with undifferentiated spondyloarthritis (USpA) have symptoms and disease features consistent with spondyloarthritis, but their disease doesn’t fit into another category of SpA. For example, an adult may have iritis, heel pain (enthesitis), and knee swelling, without back pain, psoriasis, a recent infection, or intestinal symptoms. This person’s combination of disease features suggests spondyloarthritis, but may not neatly fit into the categories of ankylosing spondylitis, psoriatic arthritis, reactive arthritis, non-radiographic spondyloarthritis, or enteropathic arthritis.
Spondyloarthritis (SpA) is a group of closely related inflammatory diseases that can affect the spine, joints, and other parts of the body. The different types share certain features but can vary in which areas they affect and how symptoms develop.
There are seven main types of spondyloarthritis: ankylosing spondylitis, non-radiographic axial spondyloarthritis, enteropathic arthritis, psoriatic arthritis, reactive arthritis, undifferentiated spondyloarthritis, and juvenile spondyloarthritis.
Spondyloarthritis is generally considered an autoinflammatory disease rather than a traditional autoimmune disease. The immune system plays a major role in causing inflammation, but unlike many autoimmune diseases, SpA is not typically associated with autoantibodies that target the body’s own proteins.
The exact triggers of spondyloarthritis aren’t known, and they can vary from person to person. Genetics, including the HLA-B27 gene, may increase the risk, but other factors may also play a role, such as severe infections, smoking, alcohol use, environmental exposures, and changes in the gut microbiome.
Though spondylitis and spondylosis are both conditions that affect the spine, they do so differently. Spondylitis is caused by inflammation, while spondylosis results from wear and tear of the spinal discs and joints over time.
A rheumatologist commonly diagnoses spondyloarthritis, since they are specially trained to diagnose and treat disorders that affect the joints, muscles, tendons, ligaments, connective tissue, and bones.
Axial spondyloarthritis primarily affects the spine and hips, causing inflammatory pain and arthritis in these areas. Peripheral spondyloarthritis affects joints and tendons outside the spine, such as the arms and legs.
Yes. A person can have both axial and peripheral symptoms. The symptoms that are most prominent help determine how the condition is classified.
Spondyloarthritis can affect various parts of the body, including the spine, hips, and other joints, such as the hands, knees, ankles, and feet. It can also cause inflammation in the tendons, eyes, skin, and digestive system.
Spondyloarthritis usually develops gradually in young adulthood, with symptoms most often beginning before age 45.
Enthesitis is inflammation where tendons and ligaments attach to bone. It can cause pain and tenderness in areas that experience repeated stress or pressure, such as the heels, feet, and other parts of the body.
Arthritis is a broad term for conditions that affect the joints, while spondyloarthritis refers to a specific group of inflammatory conditions. SpA commonly affects the spine and the areas where tendons and ligaments attach to bone.
There is currently no cure for spondyloarthritis. However, treatments can help manage pain and other symptoms, and some newer biologic medications may slow the progression of the disease in some people. Finding the right treatment can take time because people respond differently to medications.
Many people with spondyloarthritis live normal, active, and productive lives. The condition affects everyone differently, but treatments, regular exercise, and managing inflammation and pain can help control symptoms and maintain daily activities. Some people may experience more severe symptoms or complications, so working with a rheumatologist can help you manage the condition and protect your quality of life.
Spondyloarthropathy cannot currently be reversed, but treatment can help control inflammation, manage symptoms, and slow disease progression. Staying active and following a treatment plan can also help maintain mobility and function.
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