An autologous chondrocyte implantation is a two-step procedure. The first portion involves harvesting cells from cartilage in your body and then growing them in a lab until there is enough for the repair site. The second step involves the actual placement of that tissue. An osteochondral allograft transplantation (OCA) is a one step procedure that involves using cartilage from a cadaver and placing it in the area of damage in your knee. A recent review of the evidence suggests that the OCA is the better of the two procedures as far as long-term effectiveness and success with full return to sport activities.