The debilitating, chronic loss of joint cartilage known as osteoarthritis causes pain and bone decay for hundreds of millions of people every day, but new help may be on the way – in the form of a simple, single shot. Based on ongoing animal experiments, injecting a carefully engineered, slow-release drug-delivery system into the damaged joint can coax the body's own cartilage and bone cells to carry out an effective repair job in just a few weeks. "In two years, we were able to go from a