We're taking cartilage cells, and instead of sending them off to a lab, we're simply mincing them at the time of the procedure,” Dr. Guettler explained. “They're sprinkled on a biological scaffold and implanted into the knee, all in one setting." -ivanhoe.com
This procedure is used to repair "holes" in cartilage. Researchers are still working on ways to replace worn out or otherwise damaged cartilage (orthopedics.about.com).
Here is another good article on cartilage replacement using your own cells in Medical News Today