Aftermarket knees

Who here has one? Wondering about kneeling on it. Doc I am seeing has told me that they have patients that do. Have talked with a few people who said it ain't happening. Any input would be greatly appreciated.

I’ve needed two knees for probably over 20 years and keep putting it off and that’s one of my reasons. Between shop work, 7 cats, and racing I’m on my knees a lot. I just finished my third week of two shots of Synvisc today and my knees are killing me. I’ll probably have to take next winter off from
Doing porting work and start getting them replaced.