Granted, I don't see an unstable lumbar/SI listed as a most common symptom or other symptom, but that doesn't mean that some may not experience it. Joint pain and fatigue are included per this citation:

Ankylosing Spondylitis - SAA


Kind Regards,
Jay

Almost all of us long for peace and freedom; but very few of us have much enthusiasm for the thoughts, feelings, and actions that make for peace and freedom. - Aldous Huxley

Was the government to prescribe to us our medicine and diet, our bodies would be in such keeping as our souls are now. - Thomas Jefferson