A hallmark symptom of axial spondyloarthritis (axSpA) is inflammatory back pain, frequently characterized by a dull ache felt deep in the lower back, or buttocks. It is associated with inflammation of the sacroiliac (SI) joints, which are the joints linking the lowest part of the spine to the pelvis.
Inflammatory back pain usually begins before age 45, develops gradually, persists longer than three months, improves with physical activity but not rest, and can cause stiffness in the morning that lasts 30 minutes or longer. Though the lower back is usually impacted first, in some people inflammatory pain can start in the neck, or other areas. Other joints and organs can also become involved, including the hips, shoulders, eyes (iritis), gut (inflammatory bowel disease), and skin (psoriasis).
AxSpA is a broad category that includes people with and without characteristic bone changes or fusion in the spine. Doctors further classify adults as having one of two types of axSpA: