Debbie, I feel your confusion. After surgery, I believe our muscles are like they have not ever been used. We can exercise them every day, but when we are not exercising, like at night, they go back to the way they were. I'm certainly no expert in this, but if we continue to exercise and do the stretches, our muscles will retain that memory. My problem is the stiffness, one day doing really good, the next day, back to square one, they are so stiff, it's hard to get up, and have to give them a bit when I do get up to relax somewhat and be able to walk comfortably. Today has been a stiff day, just rode my bike and that really helped, at least for a while. We are still early in the recovery stages, and our days are going to be up and down for a while yet. Just try, along with me, to focus on the end of the game when our knees are so amazing we forget they are metal and plastic!! Some days, when the going is difficult, it's hard to stay positive, but it's an investment that's worth the wait and frustration and the difficult days and the not so good numbers. "This too shall pass." Take care, thinking about you. Hugs!!