Several. HLA-B27 is an indicator, but you can't diagnose definitively without seeing joint deterioration on X-Ray or MRI. Typically for Ankylosing Spondylitis it's the SI joint that has the most damage, which for me is fine so far. The problems I have are more peripheral joints, and the only changes I have on X-Ray are bone spurs at the insertion point of several tendons which can result from overuse so it's hard to attribute to a rheumatological condition with any certainty.
Most recently a rheumatological told me some people are just "bone formers" which might be true, but is still frustrating to hear as it kind of came across as very hand-wavy.
Most recently a rheumatological told me some people are just "bone formers" which might be true, but is still frustrating to hear as it kind of came across as very hand-wavy.