Six sessions. Less than five minutes each. Radiation treatment that represents just 5% of that used for cancer. And after four months, 70% of patients with knee osteoarthritis report less pain, more mobility, and a better quality of life.
The Korean study presented at the ASTRO Annual Meeting in San Francisco changes what we knew about low-dose radiotherapy: it's not just for tumors. It can also work against osteoarthritis, a condition that affects over 32 million Americans. It's a middle ground between ineffective painkillers and invasive prostheses. Something that fits exactly where it's needed: in the middle.
The Korean trial that changes the game
The team led by Byoung Hyuck Kim of Seoul National University College of Medicine conducted a randomized controlled trial on 114 patients with mild to moderate osteoarthritis of the kneeThree groups: one received low-dose radiation (3 Gy), one very low-dose radiation (0.3 Gy), and the third a placebo treatment with no actual radiation. No one knew which group they were in. Six sessions for everyone, with one restriction: only paracetamol as a painkiller, nothing else. This was to prevent the drugs from masking the effect of the radiation. as explained in the official press release from the American Society for Radiation Oncology.
After four months, 70% of the low-dose group achieved significant improvements in pain, physical function, and general condition. The placebo group achieved this at 42%. The very low-dose group achieved this at 58%, but with no statistically significant differences compared to the placebo. No radiation-related side effects has been reported in any group.
Osteoarthritis: How Low-Dose Radiation Works
Osteoarthritis begins with joint inflammation. This creates an environment in which enzymes progressively degrade cartilage tissue. Low-dose radiation has a documented anti-inflammatory effect, and they also reduce the perception of pain. They don't regenerate already lost cartilage, but they suppress the inflammatory process that continues to damage it. It's like a fire extinguisher, not a time machine: it stops the fire, but doesn't rebuild the house.
As he explained Kim:
"For severe osteoarthritis, where the joint is physically destroyed and the cartilage is already gone, radiation won't regenerate the tissue. But for people with mild to moderate disease, this approach could delay the need for joint replacement."
The Placebo Problem (and Why It Matters)
An interesting detail of the study? 42% of the placebo group reported improvements. Without receiving any radiation. As reported on Medical Xpress, this placebo response rate is consistent with other osteoarthritis trials testing injections or drugs. Kim commented: "It was surprising, and it highlights how important placebo-controlled designs are in osteoarthritis research. We need to examine this more closely in future studies."
But 70% versus 42% remains a statistically significant difference (p=0.014). Radiation works. It's not just a suggestion.
Europe forward, America backward
In Germany and Spain, low-dose radiotherapy for joint pain has been used for decades. It's an established practice. But in the United States and many other countries, including Italy, this treatment option is virtually unknown. The reason? There was a lack of high-quality controlled trials. And there's a perception problem: when you hear "radiation," you think "cancer" or "Chernobyl." You don't think "safe treatment for osteoarthritis."
“There is a misconception that therapeutic radiation is always given in high doses,” Kim clarified.
“But for osteoarthritis, the doses are only a small fraction of those we use for cancer, and the treatment targets joints located far from vital organs, which reduces the likelihood of side effects.”
Secondo a German retrospective study of 1037 patients published Radiation Oncology, low-dose radiotherapy for painful gonarthritis It had shown efficacy in 82.5% of cases with severe signs of the disease, compared to 77-78% of mild-moderate cases. Promising data, but in that case there was no placebo control.
Radiotherapy for Osteoarthritis: What Happens Now?
The Korean team continues to monitor patients for 12 months to determine how long the benefits last and whether they correlate with joint imaging. Larger trials are planned, including comparative studies with injections and cost-effectiveness analyses. Kim believes that in real-world clinical practice, combining radiation with physical therapy, weight management, and exercise could yield even better results.
Osteoarthritis, I repeat, is not reversible. But slowing it down, reducing pain, delaying the need for a prosthesis: these are concrete goals. As I told you in this articleThere are experimental approaches to regenerate cartilage using tissue taken from the patient's nose. But they are still in the experimental phase. Low-dose radiation, however, is available. All that's needed is guidelines and awareness.
Six sessions. Less than 5% of oncology radiation. Improvements in 70% of cases. Zero toxicity. Perhaps the answer to osteoarthritis was right there, in the middle, where no one was looking. Between the pills and the prosthesis, there was radiation. All it took was knowing.
