Omg, I just posted a long answer, and google made it disappear.
There is a chart at Spondylitis.org that shows knee involvement at only
20%.
It shows wrist involvement at only 5%, and mine actually started in my
wrists, so I don't know how much I trust the chart. Also, it could be
that AS in women is known to generally attack the peripheral joints
more than the back where in men, it is mostly focused in the back.
I think there is a definite chance that your stenosis could've been
related to the AS. Since the hallmark of AS is changes to the SI
joints, and since changes in the SI joints aren't apparent on xrays
years or sometimes even decades depending on the severity of the AS, it
is entirely possible that it wasn't noticed at that time.
A lot of people on AS boards talk about stenosis in different areas of
the spine.
As far as knees, I have the same problem with stairs. I also have the
same issues with my joints being hot. However, I rarely experience any
swelling and my sed rate is almost always low. (70% of ASrs have low
sed rates).
So who know if it was related? Probably was in my humble opinion after
talking to other Asers about their experiences.
Not that that is much of an answer, but there it is,
Char