A surgeon at the place I worked in Ontario (this was ~2011) did a technique similar to this but using your own cartilage ("autograft" as the poster above referred to). They would harvest cartilage from the outskirts of your knee (the part that's not weight-bearing) and use that to fill in holes in your weight-bearing cartilage. It was nice because it's your own cartilage so you didn't have the "this is a foreign body, attack it" immune response that can happen with donor tissues.

If I remember right it worked great for like a year but then the cartilage would wear down pretty fast, I would guess because it was not conditioned to sustaining the loads suddenly being placed on it. This was done typically in people with fairly advanced knee osteoarthritis, usually older, obese adults, not middle-aged super-fit triathletes; maybe results would be better in the latter group.

For donor cartilage you could take it from a weight-bearing part of the joint. Articular cartilage also typically doesn't have any connections to the nervous system or the circulatory system, so maybe the immune response issue isn't a big problem.

Definitely don't take my word as fact for any of this, I'm not a MD/surgeon/ortho, but might be worth asking your surgeon about the pros/cons of autograft vs. cadaver source.