While most folks come through a total replacement very well a word of caution...
Find out before your surgery what type of replacement knee they will be putting in and make sure your doctor has you checked for any possible allergic reaction. While rare it does happen and if it happens to you, "totally screwed" doesn't quite describe your situation. :S
Turns out I am allergic to Cobalt and Nickel, both found in the Chromium knee the VA put in. My body was rejecting that knee before I was off of the operating table. After 17 days in the hospital and 6 agonizing months working my butt off in physical therapy, I finally gave up and fired my surgeon ("Oh just keep doing your PT and it will be fine...").
The new surgeon saw the problem immediately and 8 months after the first surgery they cut my leg off a second time, called a "Revision" {Doctor speak for the first one failed}, the second knee is ceramic and I only had to spend 14 days in the hospital this time. The double layer of scar tissue that I will have forever precludes it from working well but it is better than the first one. :M
The key to a successful recovery is to work, work, work your butt off in physical therapy. Expect lots of pain and hopefully you will be pleasantly surprised if it does not come. Ice is your friend and know that "PT" does not stand for "Physical Therapist".... they are "Physical Terrorists!"
:B