Researchers say a future of hip or knee “replacements” done without surgery may be on the horizon. By employing a combination of drugs and stem-cell therapies, it may be possible to “repair cartilage before osteoarthritis sets in or an operation is needed.” Osteoarthritis, commonly afflicting the elderly, is a degenerative disease attributed to "wear and tear" but can also be caused by earlier sports injuries, obesity and other trauma to the cartilage around the knee, hip or shoulder joints. Experts explain the loss of cartilage, which does not have its own blood supply or nerves, limits its ability to mend itself and is the major cause of joint pain and arthritis affecting over 32.5 million people in the U.S. In 2017 alone, there were 754,000 knee replacements done and 448,000 hip replacements. Michael Longaker, a professor of surgery at Stanford University School of Medicine and co-director of its Institute for Stem Cell Biology and Regenerative Medicine, explains the goal...