I am very sorry that this unfortunate event is going on in your life.
I guess what doctors see in you is called "liability." RSD is on the top of the list when it comes to suits in the medical field these days.
All you can do is think positive and hope that even though they say they won't work on you, maybe it is the best thing. The rsd complications could very well outweigh the benefits of the knee surgery.
I'm only trying to give positive words and I hope things work out for you.
Best wishes.