Korean researchers found that low-dose radiation therapy eased knee pain and improved movement in people with mild to moderate osteoarthritis. The treatment, far weaker than cancer radiation, showed real benefits beyond placebo. With no side effects and strong trial results, the approach could provide a middle ground between painkillers and joint surgery.
We can’t know everything at once.
TFA reports that this works for early to moderate degeneration and it implied the mechanism of action is anti-inflammatory. It is stated explicitly that it doesn’t regenerate tissue.