Low-Dose Radiation Therapy Shows Promise for Knee Osteoarthritis Pain Relief

A single course of low-dose radiation therapy may offer a safe and effective alternative for individuals experiencing painful knee osteoarthritis, according to a recent randomized, placebo-controlled clinical trial. The treatment demonstrated notable pain reduction and improved mobility in patients with mild to moderate osteoarthritis within four months of completion.

Understanding Knee Osteoarthritis

Osteoarthritis is the most common form of arthritis, affecting approximately 32.5 million adults in the United States. Mayo Clinic defines osteoarthritis as a condition where the cartilage that cushions the ends of bones gradually deteriorates over time. This often impacts the knees and hips, leading to reduced mobility and a diminished quality of life. Initial treatment typically involves lifestyle adjustments and pain-relief medications, with surgery considered for severe cases.

How Low-Dose Radiation Therapy Works

Low-dose radiation therapy, already utilized in countries like Germany and Spain, is emerging as a noninvasive option for managing osteoarthritis pain. The American Society for Radiation Oncology (ASTRO) highlights that the radiation doses used for osteoarthritis are a small fraction of those employed in cancer therapy, minimizing the risk of side effects. In the recent clinical trial, the radiation dose was less than 5% of typical cancer therapy doses, and no radiation-related side effects were observed.

The Clinical Trial Findings

The study, conducted by researchers at Seoul National University College of Medicine, Boramae Medical Center, involved 114 participants with mild to moderate knee osteoarthritis. ClinicalTrials.gov details the trial’s design as a single-center, single-blinded, sham-controlled randomized controlled trial. Participants were randomly assigned to receive either a very low dose (0.3 Gy), a low dose (3 Gy), or a sham treatment.

After four months, 70% of patients in the 3 Gy group met the criteria for treatment responders, compared to 42% in the placebo group (p=0.014). Meaningful improvements in pain, stiffness, and physical function were also more frequently reported in the 3 Gy group (56.8%) than in the placebo group (30.6%, p=0.024). The 0.3 Gy group did not show statistically significant improvement compared to the control group.

Addressing Placebo Effects and Limitations

Researchers took steps to minimize placebo effects by restricting the leverage of stronger pain relievers, allowing only acetaminophen as needed during the follow-up period. Medical News Today reports that the sham-controlled design and limited analgesic use helped isolate the effects of radiation therapy. However, the study also noted that a substantial portion of the placebo group (around 40%) experienced improvement, consistent with rates seen in other osteoarthritis trials.

Who Might Benefit from Low-Dose Radiation Therapy?

According to Dr. Byoung Hyuck Kim, the principal investigator of the trial, low-dose radiation therapy may be particularly beneficial for patients with underlying inflammation and preserved joint structure. It’s unlikely to regenerate tissue in cases of severe osteoarthritis where cartilage is already significantly damaged. He emphasizes that this treatment should be considered as part of a shared decision-making process alongside standard treatments like weight loss, physiotherapy, and medication.

Future Research

The research team is continuing to monitor participants for 12 months to assess the long-term durability of the benefits and to correlate symptom relief with imaging-based measures of joint structure. Future studies are planned to evaluate outcomes in specific subgroups and to conduct health-economic analyses comparing low-dose radiation with other treatment options.