As of 2015, researchers have not found a way to make new cartilage cells adhere to the knee joint, make the body accept new cells, get the cells to function like cartilage or address other cartilage components, according to Dr. Jonathan Cluett for About.com. Some surgical replacement procedures exist for areas of limited damage.
Even if researchers were to make new cartilage adhere to the bone, the new tissue must be able to hold the weight of the body and glide easily for smooth motion, states Dr. Cluett. A successful cartilage injection must also address the cartilage tissue's large amounts of noncellular material that include water, collagen and other proteins. In cases of knee arthritis, cartilage injections do not address progressive damage such as the flattening of the ends of bones, changes in joint alignment and the formation of bone spurs.
Researchers are able to harvest cartilage cells and clone them in a lab, explains Dr. Cluett. Although very small amounts of cartilage can be transferred to the knee to treat damage caused by traumatic injuries or sports, injecting new cartilage to treat conditions such as arthritis in the knee is implausible as of 2015. Due to the body's failure to adequately repair knee cartilage on its own, researchers are working toward solutions such as genetic engineering and growth factors.