Our team worked for many years to invent this medical device and then perform experiments in the lab, on animals and then finally a human clinical trial to prove efficacy and safety. It worked! One way to repair cartilage is to stimulate marrow elements (“stem cells”) and cap the defect with a gel, which acts as a sponge and as a cover to hold the cells in place. Nature does the rest. The gel in question was invented by Jennifer Elisseeff and members of her lab at Johns Hopkins. For more info, see Science Translational Medicine; see this link for the article abstract.