This is a classic situation. I am in the same boat.

I need a knee replacement, but am afraid to do so because of the risk of CRPS spread.

What it gets down to for me is this. When the pain from the joint is to a point I can't take it any longer, I'll get the surgery.

I have done quite a bit of research on surgery/spread and interviewed both surgeons and anesthesiologists.... there ARE things that the anesthesiologist in concert with the surgeon can do prior, during, and after the surgery that will help "calm" down the nervous system and give you the best shot at not having a spread.

There have been many people with CRPS that have had surgery with no spread. Do these preventive blocks, therapies, etc. completely eliminate risk? No. But we as human beings have to make "risk vs reward" decisions all the time. But you need to make educated decisions, especially on something as important as this.

Eventually, you are most likely going to reach a paint of joint degradation where you have to do it. "When" is the question that only you can answer. If you choose to go ahead with surgery, please do your homework and have some deep discussions with your surgical team long before that day arrives.

Good luck!