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Pathogenesis of spondyloarthritis

David T Yu, MD
Astrid van Tubergen, MD, PhD
Section Editor
Joachim Sieper, MD
Deputy Editor
Paul L Romain, MD


The term spondyloarthritis (SpA, formerly spondyloarthropathy) refers to a group of disorders that includes ankylosing spondylitis (AS), non-radiographic axial SpA (nr-axSpA), undifferentiated spondyloarthritis (USpA), reactive arthritis, and the arthritis and spondylitis that may accompany psoriasis and inflammatory bowel diseases (IBD). SpA can also be differentiated into axial and peripheral SpA, depending upon the predominant regions of involvement. Axial SpA includes both AS and nr-axSpA, based upon the presence or absence, respectively, of abnormalities on plain radiography.

This topic review will focus primarily on the pathogenesis of AS, regarding which the most is known. The pathogenesis of each of the other members of the SpA family, especially nr-axSpA, is probably closely related to that of AS [1]. The clinical manifestations, diagnosis, and treatment of AS are presented separately. (See "Clinical manifestations of axial spondyloarthritis (ankylosing spondylitis and nonradiographic axial spondyloarthritis) in adults" and "Diagnosis and differential diagnosis of axial spondyloarthritis (ankylosing spondylitis and nonradiographic axial spondyloarthritis) in adults" and "Assessment and treatment of ankylosing spondylitis in adults".)

The clinical aspects of the other types of SpA are also presented in detail elsewhere, as is SpA in children. (See "Clinical manifestations of axial spondyloarthritis (ankylosing spondylitis and nonradiographic axial spondyloarthritis) in adults" and "Clinical manifestations and diagnosis of peripheral spondyloarthritis in adults" and "Reactive arthritis" and "Clinical manifestations and diagnosis of psoriatic arthritis" and "Clinical manifestations and diagnosis of arthritis associated with inflammatory bowel disease and other gastrointestinal diseases" and "Spondyloarthritis in children".)


Ankylosing spondylitis (AS) is a predominantly axial disease, in which the major sites of pathology are at the articulations of the axial skeleton at the entheses and the fibrous and fibrocartilaginous connections of ligaments and tendons to bone; the pathologic changes at the affected articulations include inflammation, structural damage, and excessive new bone formation.

Since the 1970s, a series of hypotheses, each incorporating the available knowledge at the time, have been proposed to explain the pathogenesis of AS and other forms of spondyloarthritis (SpA). There has been an explosion of knowledge in several areas of biomedicine since 2005 that have converged to lead to substantial progress in the understanding of AS and theories regarding its pathogenesis.

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Literature review current through: Sep 2017. | This topic last updated: Jun 21, 2016.
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