Should I have a knee replacement? see details.?

I was in a bad car accident when I was 13. I have had numerous operations to repair damage, one of which was done incorrectly and has given me pain for the last 17 years. I have been on narcotics on and off for 17 years ( I suffer from migranes as well from an anestesia reaction) My doctor (whom I do trust, I've been seeing him for about 12 years) reccomends a full knee replacement, but I'm afraid to go through with it. Had I done it when they first reccomended it I'd be on my 3rd replacement. now they have knee replacements designed for women, and they last 15-20 years on average. How do I get over this fear of surgery? I really would like to be nearly pain free for some of my adult life, but I recently had my Gall Bladder removed and had to be sedated before I was brought into the surgery center, I was having mive panic attacks. I've even seen a psychiatrist. Any suggestions? Is the replacement surgery and recovery a good or bad experience?