Some new therapies in the works for aging/injured knees [View all]

This article, besides talking about new techniques, also explains why cartilage tends not to repair itself, like other parts of the body do.

For reasons that are not entirely clear, damage to the key stabilizing structures of the knee joint often triggers a degenerative process that leads to the worn-out cartilage and chronic pain of osteoarthritis. The goal of next-generation treatment is to return the knee to its full function in as natural a way as possible, which may also slow or stop the runaway cycle that leads to arthritis. “It's repair and regeneration, rather than removal and replacement,” says orthopedic surgeon Martha M. Murray, who heads the Sports Medicine Research Laboratory at Boston Children's Hospital.

Much of the new thinking about joint repair is rooted in research into the perplexing question of why connective tissues in the joints—tendons, ligaments and cartilage—do not necessarily heal the way other tissues do. A big part of the problem in many of these structures is a relatively poor blood supply; blood contains cells and proteins that are essential to healing.

Tendons, the flexible ropes of fibrous tissue that connect muscles to bone, and ligaments, the slightly stretchy bands that link bone to bone, are less well nourished by blood vessels than are most other tissues. As for cartilage—such as the supersmooth white material on the end of bones (think chicken legs) that helps joints glide—most of it has no blood supply. “So cartilage has virtually no capacity to heal,” says Scott Rodeo, an orthopedic surgeon and researcher at the Sports Medicine and Shoulder Service at the Hospital for Special Surgery in New York City and a team physician for the New York Giants.

In addition to a paltry blood supply, the ACL's central location in the joint capsule, which is filled with a lubricant called synovial fluid, is another reason the band will not heal on its own. Wound repair normally begins with bleeding and the formation of a blood clot. Cells in the clot called platelets release certain proteins that promote healing, whereas the sticky clot itself serves as a temporary scaffold for reconstruction with new cells. In joints, however, synovial fluid dissolves clots, “so there's never that early bridge that gives healing a place to happen,” says Murray of Boston Children's Hospital. This is why a tear in the ACL does not heal, but a rip in the nearby medial collateral ligament, which runs along the side of the knee beyond the synovial fluid, slowly knits itself together.

http://www.scientificamerican.com/article/three-biotech-solutions-for-knee-repair/

Yesterday I had an ozone shot in my knee, which is relatively new. It is not approved by FDA, but Medicare does cover it.

It hurt like hell... but so far, my knee feels better.

But I will probably need 2 more. (wince)