Hi there,
look in the medical abreviations section on the main page and go to ACI, this wil tell you a bit about cartidge grafts, or what they are called anyway.
A girl I kmow's husband has had it done. They take a bit of your cartlidge and put it in a dish thing and grow the cells and re implant you with it and then it can grow neww cartlidge. I havent had it done but it sounds good.