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Introduction to Ankylosing Spondylitis
Spondyloarthropathies
Ankylosing spondylitis is a member of a group of rheumatic diseases that affects the mobility of the spine, collectively known as spondyloarthropathies (SpAs). Spondyloarthropathies are a group of related inflammatory joint diseases associated with the presence of the genetic marker called HLA-B27 and are characterized specifically by sacroiliac joint involvement in addition to other symptoms. Spondyloarthropathies affect axial joints (the vertebral column, ribs, and the sternum) and can also involve peripheral joints (e.g., feet, shoulders). The clinical features of SpA are distinct from other rheumatologic conditions such as rheumatoid arthritis. One of the prominent differences is the almost exclusive association of the HLA-B27 genetic marker with spondyloarthropathies.
Spondyloarthropathies include the following subgroups of conditions:
Ankylosing spondylitis - this is the most common subgroup and the subject of this Medifocus Guidebook.
Reiter's syndrome (reactive arthritis) - a form of arthritis characterized by inflammation of the joints (especially in the legs), eyes, genital, urinary, or gastrointestinal tract.
Enteropathic arthritis - this form of arthritis involves the lower extremities such as the knees and ankles. It is associated with inflammatory bowel disease (IBD). Inflammatory bowel disease refers to two similar but distinct conditions called Crohn's disease and ulcerative colitis that produce inflammation of the tissue lining the gastrointestinal tract resulting in abdominal pain, cramping, fatigue, and diarrhea.
Psoriatic arthritis - a type of joint inflammation (arthritis) affecting people with the skin condition known as psoriasis (characterized by thick, inflamed patches of skin covered by silver or gray scales). Inflammation may occur in hands and/or feet, large joints (e.g., knees), and sacroiliac joints.
Undifferentiated spondyloarthropathy - inflammatory, arthritic condition that does not meet all the criteria of a diagnosis of AS or other spondyloarthropathies. It is typically characterized by peripheral joint involvement and may progress to AS in some patients.
