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There are many subtypes of spondylitis, which is also called spondyloarthritis. Spondylitis is diagnosed as a specific subtype depending on how advanced symptoms are, whether the spondylitis is related to another condition, or the age when the symptoms began.
Terminology used to describe types of spondylitis has changed in the past few years. The new terminology can help us view this family of diseases as a continuum and identify and treat spondylitis earlier. Ideally, before it progresses to the point when damage can be seen on X-rays — a stage known as ankylosing spondylitis.
Different treatments may be more effective for different types of spondylitis.
Spondylitis and spondyloarthritis are umbrella terms for a family of closely related diseases that usually cause pain and damage in the spine, neck, ribs, and hips — known as the axial skeleton. Spondylitis involving the axial skeleton is called axial spondyloarthritis, or axSpA. Axial spondyloarthritis is further typed as either radiographic (visible on X-rays) or nonradiographic (not visible on X-rays). The older term for radiographic axSpA is ankylosing spondylitis. Cases of spondylitis that are radiographic are considered more severe and advanced than cases that are nonradiographic.
Spondylitis can affect other, peripheral joints and cause additional symptoms as well. All subtypes of spondylitis fit under the umbrella of spondylitis or spondyloarthritis, no matter what other terms or diagnoses may be involved.
Also called radiographic axSpA, ankylosing spondylitis is an advanced form of axial spondyloarthritis that has caused new bone growth in the spine. AS may lead to vertebrae fusing into immobility. Ankylosing spondylitis is the most severe form of axSpA. Any type of spondylitis may progress into AS.
Spondylitis associated with inflammatory bowel disease (IBD), such as Crohn’s disease or ulcerative colitis, is known as enteropathic arthritis. People with EnA have bowel symptoms and joint symptoms.
PsA can cause inflammatory pain, swelling, and progressive damage in any joint in the body. Researchers estimate that between 15 percent and 30 percent of those with skin psoriasis will develop psoriatic arthritis. It is possible to have psoriatic arthritis without skin psoriasis.
In some people, a bacterial or viral infection triggers the immune system to begin attacking the joints. This type of spondylitis is known as reactive arthritis.
Some people develop a joint condition that has some symptoms and features of spondylitis, but in an atypical pattern. Doctors may not be convinced the condition is spondylitis at all. People with cases of spondylitis that are in question may be said to have undifferentiated spondyloarthritis. People with USpA may later develop symptoms that result in a diagnosis of another type of spondylitis or another condition altogether.
Spondylitis that begins before age 16 is termed juvenile spondyloarthritis. JSpA is a rare condition. Researchers estimate that between 1 and 4 children in 1,000 develop juvenile spondyloarthritis. Children with JSpA may be further diagnosed as having a specific subtype, such as enthesitis-related arthritis (ERA), psoriatic arthritis, or undifferentiated arthritis.
Spondylitis that affects other joints besides the spine is called peripheral spondyloarthritis. Peripheral spondyloarthritis may affect the shoulders, knees, elbows, ankles, wrists, hands, and feet. It is possible to have both axial (spine/hips) and peripheral spondyloarthritis. People with peripheral spondyloarthritis may have other subtypes of spondylitis as well.
Spondylosis is not a type of spondylitis, but a separate and unrelated condition with some similarities and some important differences. It is easy to confuse the conditions since they sound similar and share many symptoms. Read more about the similarities and differences between spondylitis and spondylosis.
If someone has spondylitis symptoms that fit multiple subtypes, they may be said to have more than one type of spondylitis. For instance, if someone had inflammatory spine and hip pain and inflammatory bowel disease, they could be diagnosed with enteropathic spondyloarthritis. If the same person developed inflammatory pain in peripheral joints such as their hands and feet, they could be said to have both EnA and pSpA.
For another example, if someone had a skin rash and joint inflammation in their hands and feet, they may initially be diagnosed with psoriatic arthritis. If they developed spondylitis in their spine that began fusing the vertebrae together, the person may also be diagnosed with ankylosing spondylitis.
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