Pains in both legs

I am 70 years old, and had a TKR on my left knee three months ago. After the surgery, the surgeon remarked that he thought there was an abnormally large amount of scar tissue which he had to remove.

Now, I go for physiotherapy three times a week, and seem to be making progress, having gone from the walker to the cane, and, by no, to walking, in a somewhat wobbly fashion, without the cane. The outside of my left knee feels numb, but I am told that is to be expected for a while

While lying down or sitting, I have very little pain. When I stand or walk, I get stiffness and pain below the kneecap, not only in my left leg, but also in the right one, which was not operated upon. Has anyone else had sand experience with a reaction?