Mine progressed with an obvious loss of ROM right away (mostly due to pain), with signs that SI fusion was underway, enough for a comparably quick diagnosis after just 2 yrs of symptoms. This was followed by an obvious loss of height in my 20-30's.
After that, it never occurred to me to ask for xrays to be repeated - I knew the pain I was in, and to have xrays would only confirm what I was busy trying to deny. (I'd semi-convinced myself that despite the non-stop pain, I might escape fusion. Seems a silly thought in hindsight.)
Sometime, early 40's or so, I had a full set of xrays taken to assess whether I'd be eligible for a biologic. (The rheumy suggested it was possible I was too far progressed! A thought that had not occurred to me.) Turned out that my SI were solid, lower lumbar affected, syndesmophytes lower to mid spine with a bit of fusion in my neck. And hip joints somewhat damaged.
Still, some of the loss of ROM was not from fusion, as I did gain back quite a bit of flexibility and range, after some time on Remicade. Best. Med. Ever. (for me!)
Turns out there is a Santa Claus!!!
Yep, we are all different. Prognosis is tricky to guess with AS. Considering lifetime exposure, limiting xrays as much as might be sensible still seems like a smart plan to me.
I also basically believe that for those of us who do have fusion, that it was not due to a lack of moving.
