Thanks for the good advice.
I currently use a very tall mounting block that my wonderful spouse built for me; it allows me to throw my right leg directly over my horses's back while standing flat footed on the block; so I don't have to bear all my weight in my left stirrup while twisting and swinging over.
It's very painful even to mount from a short mounting block or a truck bed or trailer fender. I even dismount onto my tall block to minimize knee pain.
My doctor clearly doesn't understand the specific stresses of horseback riding; while a sports medicine guy, I think he's in that group of folks that thinks it's not really exercise because the horse does all the work.
So that advice, to make sure he really understands what my expectations are, is particularly on point.
I've ridden in the Sprenger stirrups for years, I don't know how anyone over 40 rides without them.
Thanks for your posts, would love to hear more.