@kdo0827, I was told when I had my knee replaced to avoid kneeling on the knee directly if possible, especially on hardened surfaces. I am 13 years post-op from my knee replacement and still don't kneel on my knee, and if I do accidentally it hurts. It is about the only thing that does hurt. I can see how this would be more difficult with both knees replaced though, as I still have my left knee in tact.