The day I had my stem cell procedure done, I notice two others who followed me and they were younger males. The drilling in the hip for the stem cells had very little pain. Blood was taken from both arms, it was mixed with the cells, three hours later the cells and blood was injected in the knee. I needed a cane to go home. The next day I had one more injection. Four weeks of relaxing, reading, tv etc and I was good to go. My knee was bone on bone. I was fitted with a neat knee brace and I do wear it when I golf, bike and garden. Not sure if I need to but it's my crutch. Having had a terrible time with total knee replacement I just use it for peace of mind. I have been told by the doctor if I feel I need a booster shot that can be done.
There are a lot of doubters out there but I ignore them. Downside is no insurance coverage. I suspect it will happen some day when you consider the cost of a total knee replacement, three days in a hospital and many trips for p/t. It was a bad time for me and my frustration was I went into the surgery in good shape. I had worked out for a year to have good strength etc. did not work out for me. I do have friends that it worked for them. If you have the finances then you must weigh your options.