I did a google search and found that variable include age, range of motion and your physical condition. That said, the estimated therapy period appears to be 4 weeks.
I had a t k replacement in 2004 its stiff and some days I am in so much pai n I really do not know what to do, I am going to have the other knee done in 4 weeks time is this going to be the same . What causes such pain please help Jan
My father in law had both knees replaced a couple years ago and he has done great. But I know another man who had a double knee done, decided the therapy was too painful, and now he can't walk at all.
The key to knee replacement is to diligently do your post-surgical physical therapy no matter how bad it hurts. I'm pretty sure my FIL did his much longer than 4 weeks. He remains as active as possible - golf, ballroom dancing, and especially bike riding. Even when his knees were hurting he could almost always get on his bike and ride.
Because of the complex structure of the knee, recovery is longer than for another joint, like the hip. I've had both hips replaced and recovery from that is easy compared to the knee. It's a ball, a socket, and you're done. The knee has tendons and ligaments and bones that all have to work perfectly in concert in order to the joint to function properly.
So the bottom line is, after the surgery, grit your teeth and push push push through the post-op therapy. You won't regret the hard work.