My mom had to have a revision done last year on her left knee. She could barely walk, function. My parent's live in Indiana in the summer months, she seemed fine then when we would see her. Then they leave in October for Florida for the other 6 months. She thought maybe she had pulled or twisted her replaced knee some how, but went to an OS and he said she'd need a revision.
All I know is she is doing really well with it, she was 76 at the time she had the revision done. I guess in answer to your question.. I am wondering how long I can put it off? Until you can't take the pain, discomfort anymore, but don't wait to long. My mom waited almost too long and being the stubborn person she is almost didn't have enough cartlidge to connect to have the surgery done.