@happyat76 Your symptoms sound like mine. I am slightly younger than you are, I had my second TKR at age 70 but I am so glad that I did. I couldn't walk long distances prior to it but I am almost unstoppable now. Not everyone gets such great results. I believe the most important thing is to get a really great surgeon. Also, there are two big improvements on TKRs, Makoplasty, and the Conformis knee. They both seem to have higher odds of being successful than the older ways. My TKR is a Conformis knee.
I have also read that the sooner you get it done the better off you are because the muscles are more equipped to help your recovery whereas if you wait a long time the muscles have weakened. I also think that carrying a lot of excess weight can make your recovery more difficult, although many people do have excess weight and have successful TKRs.
It is a tough decision, one only you can make. You really do have to weigh the pros and cons. A friend of mine who is a doctor (not orthopedic) really tried to discourage me from having it done because many people are not happy with the results but I think if you research carefully and choose the best possible surgeon, then that greatly increases the odds of it being very successful.
I will be very interested in hearing what you decide. Please keep us up to date on your progress.
JK