I have only had a hip, no knees. Recovery from the hip replacement was fast and essentially painless. Doc told me not to skip rope, not to jog or sprint, but ok to run if I needed to. He said, "Ok to run away from bad guys." So this is what I have done. For me it is not like my own good hip, but it is a real improvement over the severely damaged one I had replaced.
Apparently hips tend to be better than knees, knees better than shoulders, ankles and other joints. And really try to avoid back surgery. I have one friend who has had 5 of these, and it gets worse every one. He says he is done with trying this.
One surgeon told me that he has patients who are joggers who have essentially no cartilage in their knees, and yet they do not have extreme pain running long distances. So it just seems to boil down to your degree of pain and or disability. I second what Aja said, choose a very experienced, active surgeon. It's not just him, but the whole team that gets better every one they do.
Ha