Hi Hiker,   Really good thoughts and questions.   The truth of it is that
some people do really well after a shot to the knee for 3 months to a year
and some people the steroid shot does not help at all.   It has a lot to do
with how much cartilage is left in the knee and if the steroid controls the
inflammation in the area.  It is a good idea to have the doctor test the
fluid that comes out of the knee before the shot goes in to check for
infection and other things.  It is something to talk to the doctor about
before the shot.
   On average a person can get as many as 3 shots in a joint in a year but
there is a price to pay for that many shots and another thing to talk to
your doctor about.
   Please rest the joint as best you can to keep from driving the steroid
out of the area it was put.   Some people will start doing stairs because
they can again. Please do not be one of those people and it will last longer
for you.   Good luck.
Harv