DW has had 2 knees replaced 4 years apart. Ask for and do exercises BEFORE your surgery to strengthen the muscles you'll need after your surgery. As others have said, do your post surgery exercises religiously and perhaps a bit more. BE ANAL ABOUT IT, even if it hurts. The payoff is full ability to do everything you want to do and the downside if you don't do the exercises is that you will be in constant pain and will be able to do very little. My DW is in the former category, and some good friends are in the latter condition. DW is 74 and just had a shoulder replaced. Much longer PT and recovery time, but I'm sure the ultimate results will be similar to the knees. Good luck.