tdmidget - I had TKA (total replacement) of my right knee in 2015 at age 55. Like above, I only know about it when I go to the dentist (take some antibiotics) and sometimes at the airport.
Thing to realize - the first part of PT and recovery is quite difficult, parts of it painful, and very hard work. But that only lasts a few weeks. Total recovery - meaning you knee stops getting better - well in my case it was 2 years before I thought - yeah, it's perfect now, can't get any better. Mind you at 5 weeks it was way better than it was before, and by say 2 months it was light years better. It's just it kept getting *even better* for a very long time.
But the very hard recovery, and the very long recovery, are not at the same time. There is a short very hard time, and then a long "it gets better every week" time.
By the way, I do things like cyclocross racing - surgeon was fine with it.
Good luck.