Knee pain is mostly caused by osteoarthritis; the most common form of arthritis and is caused when the cartilage, which cushions joints, becomes injured and worn. Cartilage has no pain receptors, so injuries go unnoticed until much of the cartilage has worn away and the joint is damaged.
Artificial knees can rid recipients of chronic pain and improve quality of life, research suggest that pain persists in as many as 20 percent of knee replacement patients. Full range of motion often is not restored.
Since cartilage cells don’t have their own blood supply, it has long been thought that these cells could not regrow. But some research suggests that may be wrong.
In a two-year study, which simply followed the natural history of 325 patients (avg age 45), 37 percent of participants showed improvements in cartilage as measured by MRI, compared with 33 percent whose cartilage worsened. Men, younger adults, those with thicker knee cartilage and people who shed more pounds between the first knee measurement and the second two years later were more likely to show improvements in cartilage. https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/410037
In October, Duke University reported new evidence showing that cartilage in human hips, knees and ankles can regenerate on its own — in the lab, anyway. https://advances.sciencemag.org/content/5/10/eaax3203 The challenge is that cartilage repair takes a lot of time, since the only way cartilage cells are nourished is by being bathed in joint fluid.