Like you, I also did the Master Gardener program 15 years ago. I have not yet gotten around to buying knee pads, but I had to cut down hundreds of outdoor mums a few days ago, and found that as long as I keep 70% of the weight on the good knee, and cheat a little bit by purtting less pressure on the outside of the TKR knee, I can actually kneel for a limited time as long as it’s on soft earth or grass. Not perfect, but it’s a start. Thank goodness I have no problems whatsoever getting down to or up from a kneeling position, even though I do use my arms to help push up because it is easier that way. So stem cells work? I am not sure I want another TKR should the healty knee deteriorate as well.