WEDNESDAY, Sept 30, 2026 (HealthDay News) — Low doses of radiation targeted to arthritic knees may ease symptoms and even slow disease progression, new research suggests.
The study conducted in Russia tracked almost 300 patients with knee osteoarthritis, some of whom were treated with radiation and tracked for nearly 12 years.
"Patients experienced sustained improvement in pain and function; [their] MRI showed less joint deterioration and years later, we saw less disability and, in patients with grade 2 disease, fewer knee replacements," said study co-author Dr. Nagendra Koneru, a radiation oncologist at Loyola University in Maywood, Illinois.
"Together, these findings raise the possibility that treatment may influence the longer course of osteoarthritis," he said in a news release.
The findings were presented in Boston on Tuesday at a meeting of the American Society for Radiation Oncology.
As the authors explained, many people are familiar with the use of high-dose, targeted radiation for conditions such as cancer. Radiation delivered at lower doses is less potent but can still reduce local inflammation around arthritic joints.
Inflammation can worsen and speed the progression of arthritis, the researchers explained. Exercise, medications or injections and maintaining a healthy weight can relieve symptoms, but they do little to slow the course of the disease.
Radiation therapy may do just that, the study found.
The trial included 292 people with symptomatic knee arthritis in early stages 0, 1 or 2, based on the bone's appearance on X-ray or MRI.
The participants averaged around 38 years of age. Some got medication alone (glucosamine and chondroitin), while others got medication plus the radiation therapy.
The radiation delivered to the knee was low-energy X-rays.
Patients typically reported an immediate lessening of knee pain after the radiation procedure. They also reported significant and lasting improvements in physical function and quality of life compared to folks who had been on medication alone.
That's not surprising, since low-dose radiation has been routinely used to ease arthritis in Europe for decades, the researchers said.
MRI scans also showed less bone deterioration in the knees after patients received low-dose radiation therapy.
However, the big news came from longer-term outcomes: Over almost 12 years, study participants who got the therapy were 67% less likely than those who had not to report disability.
Among those in stage 2 disease, 31% of those who'd received the therapy went on to become disabled, compared to 61% of those who hadn't gotten the treatment.
Similar findings were found for knee replacement: Only 14% of those with grade 2 arthritis who received radiation therapy needed a new knee over the next 12 years, compared with 36% of those who didn't receive the treatment, the researchers said.
“Grade 2 disease may represent a window where osteoarthritis is established, but extensive joint damage has not yet occurred,” Koneru said. “The combination of less disability and fewer knee replacements in these patients is particularly encouraging. It suggests an opportunity to study whether treating inflammation earlier can change the longer course of the disease.”
The therapy did not seem to raise cancer risk.
No radiation reactions in the affected knees, or cancers within the treated area, were reported during the nearly 12 years of follow-up, the authors said.
Koneru noted the next step is a multi-center randomized trial that compares people getting low-dose radiation against those who only get a "sham" procedure but no real radiation.
"For osteoarthritis, we have treatments that can help patients feel better, but much less evidence that they can change what is happening inside the joint," Dr. Gopal Bajaj noted in a news release. He’s co-chair of the American Society for Radiation Oncology's Functional Radiation Medicine Task Force.
"What makes these findings interesting is that the patient-reported improvement was accompanied by a measurable difference on MRI," said Bajaj, who was not involved in the new research.
"That moves the question beyond pain relief alone. The long-term disability data add another reason to test whether low-dose radiation can affect the course of early osteoarthritis in a larger, rigorously controlled trial,” he added.
Because these findings were presented at a medical meeting, they should be considered preliminary until published in a peer-reviewed journal.
More information
Find out more about knee osteoarthritis at Mass General Brigham.
SOURCE: American Society for Radiation Oncology, news release, Sept. 29, 2026
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