Osteoarthritis

In the video "Knorpel wächst nach!" ("Cartilage grows back!"), the biologist and sports scientist Dr. Wolfgang Feil explains that cartilage can regenerate if the inflammation in the joint is stopped, contrary to the common belief that cartilage never grows back. Well worth watching.

On a related note: red light is also used for joint problems, more under Red Light Therapy. Glucosamine and chondroitin, which I take for my joints, are listed under Longevity.