My shiney new knee

[nzoomed]

Looks quite an interesting treatment, there is alot of research going into this field, it can only get better over time.
I guess it also depends somewhat on how far the arthritis had progressed?

Yes. Essentially my surgeon made the call from my MRI that I had insufficient cartilage remaining (i.e. bone on bone) in the medial meniscus for PRP to be viable. Post surgery he reported that the lateral meniscus had also reached its use by date so a full joint replacement had been the right call.

From what I understand if the cartilage is severly worn and/or calcification of the joint is present then the rejuvenation provided by PRP won't be successful. Works well on a joint that has moderate wear but not too far beyond that.

I'm getting about without crutches or sticks, with care, and had the stitches in the navigation post wounds and all dressings removed yesterday. Close to 90 degree of bend so far with physio starting tomorrow.

That would make alot of sense, it needs alot of healthy cells to regenerate from.
That's good to hear you are now mobile.
It took my father a bit, with lots of exercises but he got most of his movement back, if not more, because his arthritis was so bad that he couldn't get much movement. 
Stupid doctor removed his cartilage decades ago as it was a silly idea they had back then to treat it. Just made it worse  but now at long last he is free of pain.