Tim, there are two different ways of classifying spondyloarthritis. AS in the old classification is radiographic axial spondyloarthritis in the new classification. This link explains the two systems of classification.https://www.spondylitis.org/Types-of-Spondylitis
Thanks for pointing that out, a lot of the articles I was finding used Axial Spondyloarthitis and Ankylosing Spondylitis in the same sentence as if they were two different conditions.
Still I find it’s interesting that there is a decent enough population of people with a form of AS that does not show on imaging that a Non-Radiographic form of the disease seems to have recently gained some acceptance in the medical community.