Did one knee, pretty bad. Had stem cells on that knee about 5 years ago. My goal was to avoid another TKR. I do not play tennis anymore. I do a lot of biking and gardening. I can knell on the stem cell knee and i use a stem cell brace which is great for golf. I tend to do PRP every other year. That takes care of my arthritis. Yes, it is expensive, but i am avoiding what was one miserable time in my life. I have friends who have had good luck and those who have had bad luck with their TKR. They cannot get on their knees to garden etc. I made the decision. My Dr says i will never have to have TKR as long as i keep up with PRP. I am now 80 and glad i made the decision. Currently have 3 hole in ones in golf. Hah