Don't really like doing this, but you asked for all points of view.....I had a total knee replacement seven years ago, and it should have been followed by the other knee three months later......The surgeon managed to damage the nerves and soft tissue surrounding my knee, and I have been in worse pain ever since, and needless to say I am too afraid to have the second knee done.......
I have a good friend who had hers done shortly after me and she has had no trouble at all....My DH had a hip replacment four years ago and it has been wonderful for him....
So any operation can go wrong, but on the other hand it can go smoothly and change your life...