Constant pain and stiffness in the low back, buttocks, and hips that continue for more than three months. Spondylitis often starts around the sacroiliac joints, where the sacrum (the lowest major part of the spine) joins the ilium bone of the pelvis in the lower back region’
A segment from Dr. Michael Weisman's Spondylitis Educational Seminar presentation (to the right) given in Denver, CO in 2008 describes the differences between mechanical and inflammatory back pain. Inflammatory back pain is the variety associated with ankylosing spondylitis and other spondyloarthritides.
When determining if the back pain is inflammatory in nature and related to a disease such as ankylosing spondylitis, the following is often taken into account:
Onset of pain is usually under 35 years of age and is insidious
Pain persists for more than three months (i.e., it is chronic)
The back pain and stiffness worsen with immobility, especially at night and early morning
The back pain and stiffness tend to ease with physical activity and exercise
NSAIDs are very effective in relieving pain and stiffness in most patients
Note that inflammatory back pain by itself should not be used to diagnose ankylosing spondylitis. Instead it is a very important characteristic which the physician considers along with other findings such as x-ray or MRI evidence of sacroiliitis, the detection of the gene marker HLA B27, or the history of another related physical finding such as Iritis.