Knees and other joints regrow some lost cartilage with some outside aid, research suggests
“Cartilage doesn't heal.” That's what doctors often tell us when we injure the flexible tissue that lines our hips, knees and shoulders or when osteoarthritis has eroded it so that our joints hurt when we move. I've certainly heard it myself from orthopedic surgeons who explain that cartilage has no blood supply to bring repair cells and nutrients to an injury site. Yet it's always struck me as improbable that a living tissue could not replace damaged cells.
Kraus is one of a small number of scientists who studies the slow turnover in this tissue. In a surprising discovery, she and her team reported in 2019 that the production of proteins associated with repair and regeneration differs by joint: It is greater in the ankle than in the knee and greater in the knee than the hip.
There is other evidence that human cartilage can regenerate. A procedure called joint distraction is being tested as a way to promote healing in patients who have bone-on-bone knee arthritis and are too young to be good candidates for total knee replacement. The procedure involves placing pins above and below the knee and using an external device for six weeks to separate the upper and lower leg bones by five millimeters. This opens up the joint space.