I have had three knee ops so far, and am pretty sure I will need another to replace the partial in my left knee with a full in a year or two.
The advice above to begin PT before the operation is good. The stronger the leg is, the quicker you will recover. And keep doing the PT for a couple of months after the op. For me, after initial recovery at home, going to a local clinic/gym and receiving PT was a better option than trying to do it on my own at home
If you are overweight, which most of us who develop bad knees are, work on losing weight. My first surgeon would not operate until I lost about 45 lbs. I went from 270 to 225 in about six months by fasting for 36 hours once a week.
For the first two ops I just had ice packs. For the third I bought an ice machine. Much better! I think they cost about $200 but definitely are worth it for convenience and efficacy.
As everyone says — and every says it because it is very true — take the PT very seriously. Yeah, it hurts. But the pain is worth it.
Take the pain killers. Stay ahead of the pain. Early on, I took the max oxycodone doses at the minimum intervals my doc prescribed, keeping a careful record, writing down doses and times in a notebook. I did this to ensure I stayed within my doctor's guidelines.
A useful PT trick is to time the painkillers so that they hit max effect just as your PT guy is stretching the bejeez outta your traumatized knee..
(I have tried to understand why people get addicted to oxy, as I at no point felt it was a problem and tapered off easily as the pain receded with time passed. I think for people with chronic pain, with pain that does not lessen with time, it can become addictive as they need it for constant, long-term, severe pain. I don't think it is dangerous for those with temporary severe pain which gradually lessens — which is the case with knee replacements — and who carefully follow their doctor's dosage instructions.)
One final tip: To lift up, move, your leg with the replaced knee, stick your good leg under it at the ankle, and lift it with your good leg. Helps with getting into and out of bed, or changing your position.