Spondylitis is arthritis of the spine. Ankylosing means stiffened. So ankylosing spondylitis is a type of arthritis that makes your spine painful and stiff.
[msdmanuals.com]
Ankylosing spondylitis (AS) is commonly referred to as arthritis of the spine. Typically, the painful form of arthritis strikes people, mostly men, in their 20s.
[verywellhealth.com]
Ankylosing spondylitis, in addition to affecting your spine, also causes swelling, stiffness, and pain in your large joints, fingers, and toes Sometimes it affects other parts
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