Very good article at the link given!
I was struck by this paragraph which I copied :

Discrepancies between patients’ self-reported ability to kneel and observed ability suggests that patients can kneel but elect not to. Reasons for this are multifactorial, including knee pain/discomfort, numbness, fear of harming the prosthesis, co-morbidities and recommendations from health professionals. There is currently no evidence that there is any clinical reason why patients should not kneel on their replaced knee, and reasons for not kneeling could be addressed through education and rehabilitation.

Yes the “ facts” are interesting but the point of this kind of site is sharing our experiences … with kindness and respect