Researchers are testing low-dose radiation to treat the painful symptoms of osteoarthritis in the knee.

The study, published by researchers in Korea and presented at the American Society for Radiation Oncology (ASTRO) annual meeting in September, suggests that a single course of radiation can be a “safe and effective” treatment option.

Knee osteoarthritis is a degenerative joint disease causing pain, swelling and stiffness in the knees that worsens over time.

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The randomized clinical trial enrolled 114 patients with moderate-to-mild knee osteoarthritis who were each assigned a very low dose of radiation, a low dose or a placebo. The only other pain relief used during the study was acetaminophen.

The participants went through six sessions as researchers assessed “meaningful improvement” in at least two of the following markers — pain, physical function and overall assessment of condition.

The patients also completed a questionnaire to report pain, stiffness and function. None of them recorded any treatment-related side effects.

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After four months of treatment, 70% of the low-dose participants met the criteria, compared to 42% in the placebo. Those in the very low-dose group saw a 58.3% improvement.

These findings suggest the low-dose regimen “drove relief beyond placebo effects,” experts noted in a press release.

A researcher suggested that radiation therapy could delay the need for joint replacement. (iStock)

In the low-dose group, 56.8% recorded meaningful improvements in pain, stiffness and physical function scores, compared to 30.6% in placebo.

The study concluded that low-dose radiation led to significant reductions in pain and improved function after four months, a “small fraction” of what is typically used to treat cancer.

“For people with mild to moderate disease, this approach could delay the need for joint replacement.”

Dr. Byoung Hyuck Kim, principal investigator on the trial and an assistant professor of radiation oncology at Seoul National University College of Medicine, Boramae Medical Center, noted that people with painful knee osteoarthritis “often face a difficult choice” between the risk of side effects from pain medications and the risks of joint replacement surgery.

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“There’s a clinical need for moderate interventions between weak pain medications and aggressive surgery, and we think radiation may be a suitable option for those patients, especially when drugs and injections are poorly tolerated,” he said in a statement.

Other lifestyle factors, such as weight loss, should be factored into the consideration of low-dose radiation as treatment, according to the researchers. (iStock)

Radiation therapy may be a better fit for patients with underlying inflammation and preserved joint structure, Kim added.

“For severe osteoarthritis, where the joint is physically destroyed and cartilage is already gone, radiation will not regenerate tissue,” he said. “But for people with mild to moderate disease, this approach could delay the need for joint replacement.”

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This treatment should also be considered alongside other lifestyle factors, including weight loss, physiotherapy and medications because responses could be “even stronger when radiation is properly combined with other treatments,” Kim said.

“And patient satisfaction may be higher than with current options alone.”

The study did have some limitations, the researchers confirmed, including the relatively short follow-up period.

The researchers are planning for larger trials to evaluate the outcomes in specific groups of people, comparing low-dose radiation injections with medication regimens.