The first time Anna Shapiro, MD, professor of radiation oncology at SUNY Upstate University Hospital in Syracuse, New York, treated osteoarthritis with low-dose radiation, a retired physician had come to her with a stack of research requesting it.

“He had limited use of his thumb from arthritis in his joint, and he came to me with literature and said, ‘Would you do this for me?’” she told Medscape Medical News. She had already read some of that research herself, including the protocol, and she agreed. “He did very well. He kept moving his hand, [saying], ‘I can use my hands.’ He was so happy.”

The experience led Shapiro to learn even more about the treatment option, even traveling to Germany, where much of the research comes from, to take a course on it.

Shapiro is among a growing number of radiation oncologists who have begun offering low-dose radiation for osteoarthritis in the hands, feet, knees, shoulders, elbows, and hips. While it’s unclear how widely the treatment is available in the US, interviews with multiple radiation oncologists revealed that awareness is growing rapidly.

“We’re trying to educate rheumatologists that it’s an option,” Shapiro said. “Radiation oncology sounds like we only treat cancer, but we actually treat a lot of other benign conditions with radiation.”

While this therapeutic approach had been new to Shapiro, she soon discovered it’s not actually “new” at all.

“It falls into the category of everything old is new again,” she said. “Radiation for arthritis was used as long as radiation has been available.” Indeed, the treatment’s first published use was in 1898, Austin Kirschner, MD, PhD, associate professor of radiation oncology at Vanderbilt University in Nashville, Tennessee, told Medscape Medical News. “It was widely used in the US and Europe through much of the 20th century, but its use declined in the US in the 1970s and 1980s as new pharmacologic options became available and concerns about radiation risks emerged,” he said. But low-dose radiation treatment remained a standard osteoarthritis treatment in several European countries, especially Germany, he added.

Today, as clarity about the relatively low risk for malignancies from exposure has become evident and the strength of evidence on radiation’s effectiveness for osteoarthritis has grown, awareness of the treatment option is increasing on the Western side of the Atlantic among rheumatologists, primary care doctors, orthopedic surgeons, interventional anesthesiologists, and physical therapists.

“I don’t know who’s driving it necessarily; the rheumatologists with whom I’ve worked are very excited and eager about this because their hands are tied at a certain point with a lot of their osteoarthritis patients,” Robert Reznik, MD, assistant professor of radiation oncology at Cedars-Sinai Medical Center in Tarzana, California, told Medscape Medical News. “They’re willing to try this. The benefits, especially for patients that are really at their wit’s end because of the pain and swelling and the limitations in range of motion, far outweigh the risks.”

No national data currently exist on how widely the treatment is used in the US — Kirschner said it’s unclear how many patients receive the treatment or how often referrals occur — but many major academic institutions now offer it, as well as a smattering of community clinics throughout the country.

“When we discuss the treatment with colleagues, we are often met with enthusiasm,” Kirschner said. “Physicians are glad to learn this is another treatment option for patients who are often seeking a noninvasive management approach. They want to exhaust every kind of nonsurgical option and make sure patients get the maximum quality of life and the minimal risks of the treatment.”

Older Patients Are Ideal Candidates

Current options for osteoarthritis prior to joint replacement include disease-modifying agents, anti-inflammatories, physical therapy, steroid injections, and lifestyle modifications, such as weight loss and exercise. Ideally, those seeking radiation therapy have radiographically confirmed osteoarthritis with persistent symptoms — a pain score of at least 4 out of 10 — after having exhausted all these options that they aren’t contraindicated for.

“Radiation falls somewhere between when the patient has tried other conservative measures [but is not] quite ready for joint replacement,” Shapiro said. It’s also most effective for mild-to-moderate osteoarthritis, where patients still have some partially healthy joint architecture and have not yet progressed to bone-on-bone arthritis, by which point radiation is unlikely to be as effective, Kirschner said. “It may help with decreasing inflammation, but it’s going to be much more effective if you catch it a little earlier,” Shapiro said.

The most appropriate candidates are older than 40 years or, more conservatively, older than 50 years, to reduce the risk for later malignancies, even though that risk remains extremely low, Kirschner said. In a 70-year-old man who receives low-dose radiation treatment for his knee, the estimated lifetime risk for a radiation-induced cancer is around 0.03%, he said, and even that may be an overestimation because it’s derived from whole-body exposure. But risk is higher in younger patients — hence the recommendation only in older patients — or for joints near radiosensitive organs, Kirschner said.

Although low-dose radiation is not included as a recommended treatment in the latest American College of Rheumatology/Arthritis Foundation guideline for the management of hand, hip, and knee osteoarthritis, radiation oncologists interviewed for this article have reported no difficulties with payer coverage. Medicare has covered it for decades, Shapiro said, likely because it had been an established treatment for years before it was abandoned in the 1980s.

Durable Effectiveness With Little Risk, Side Effects

There are multiple different mechanisms by which the treatment is theorized to work, Kirschner said. “Radiation modulates immune cell function, reduces proinflammatory cytokines, polarizes macrophages toward an anti-inflammatory phenotype, and decreases oxidative stress on the joint,” which differs from the way nonsteroidal anti-inflammatory drugs (NSAIDs) or corticosteroids target specific inflammatory pathways or mediators, he said. The plain language that Reznik and Shapiro use in describing the mechanism to patients is that the radiation halts the “inflammatory cascade” that contributes to osteoarthritis.

Kirschner, who was senior author on a 2022 review of low-dose radiation for osteoarthritis, said that multiple retrospective and prospective studies, mostly from Europe, show moderate- to long-term pain relief with mobility and quality-of-life improvements in about 60%-90% of patients.

“Many large case series and cohort studies show promising pain relief and improved joint function with minimal side effects,” said Bruce McGibbon, MD, associate professor of therapeutic radiology at Yale School of Medicine, New Haven, and medical director of Radiation Oncology at Greenwich Hospital, Greenwich, Connecticut. “So, it’s definitely something to consider for patients over age 65 with refractory osteoarthritis. And as randomized trial results become available, the potential use cases could grow significantly.”

Results from randomized controlled trials are far more limited and have been mixed, but a handful show promise, with several other trials starting or ongoing.

A 2023 Russian study of 292 patients with knee osteoarthritis cut the risk for disability in half among those receiving radiation and pharmacology (hazard ratio, 0.49; 95% CI, 0.26-0.95) compared with those receiving pharmacology alone. Over a decade of follow-up, 90% of those who underwent radiation had no disability compared with 80% in the control group. In a smaller 2025 study from Iran, 60 patients aged 65 years or older had a baseline pain score of 9/10 for knee osteoarthritis. The radiation group’s pain dropped to 6/10 (P < .001), whereas there was no significant change in the sham group’s pain scores. In the intervention group, 85% of patients also reported less use of pain medication and improvements in performance status.

The pain relief can last from several months to years, with studies reporting that 30%-60% of patients maintain significant pain reduction 1-2 years after treatment, Kirschner said. Patients do not typically experience acute side effects, though in rare cases they may have some slight redness, milder than a sunburn, on the skin of the area radiated. So far, although malignancy induced by osteoarthritis radiation treatment remains a small theoretical risk, no cases of secondary malignancy have been reported in research for patients older than 40 years.

Still, not all clinicians are convinced that the benefits are worth the risk given other available treatment options. The American College of Rheumatology has yet to recommend low-dose radiation treatment, and it is not considered a standard of care, Bibi Ayesha, MBBS, associate professor of rheumatology and director of the Vasculitis Clinic at Montefiore Medical Center and Albert Einstein College of Medicine in Bronx, New York, told Medscape Medical News.

“There is very limited literature for consensus guidelines for treatment planning of this low-dose radiation therapy for osteoarthritis. Any exposure to radiation can cause an autoimmune shift that can potentially increase your [risk] for cancer,” she said. Meanwhile, the range of alternative options includes joint braces, NSAID creams, and other topical pain relievers. “Why would you want to expose your patient to radiation when you have other treatment choices?”

Hands, Shoulders, Knees, and Toes

While no consensus guidelines from a US medical society currently exist for low-dose radiation for osteoarthritis, radiation oncologists who offer the treatment follow guidelines from the German Society for Radiation Oncology. The most commonly treated joints include hands, feet, shoulders, knees, hips, elbows, and toes — nearly all extremities where the risk for radiation exposure resulting in malignancy is lower than if it were directed in an area with more organs.

“One of the most common areas where radiation can make a big difference is hands and feet because orthopedics doesn’t have a lot to offer for small joints, and, functionally, it impacts patients in a really huge way.” Shapiro said clinicians avoid treating arthritis in the spine with radiation because bone marrow production is still occurring there even in older patients. “We worry a little bit more about causing leukemia because [it] has a shorter latency period” between radiation exposure and potential development of a malignancy, Shapiro said.

Although some clinicians also treat arthritis in the ankles, the German guidelines do not currently recommend the therapy for ankle joints.

The treatment protocol begins with an initial consultation, followed by a CT scan to determine the affected area and plan the treatment. Patients then receive six treatments of 0.5 Gy each, conducted two to three times a week over 2-3 weeks. Each treatment lasts about 15 minutes and carries the radiation exposure equivalent of “probably a few CT scans,” Reznik said.

Shapiro reevaluates her patients 3 months later, and if they had an incomplete pain response, the course can be repeated. Kirschner said about half of those who did not respond to an initial course will respond to a second round 3 months later.

Shapiro said her first patient’s physical therapist was so impressed with the results that he told other patients about it. “They have a group of very active older adults who told one another, so there’s a lot of word of mouth going around,” Shapiro said. And as baby boomers continue aging, demand will likely grow as well, Kirschner and Shapiro said.

“It’s a demand that we’re able to meet at the moment and hopefully will continue to grow that way, as policies and [logistics] continue to support it,” Kirschner said.

Because only radiation oncologists can offer the treatment, they do need to balance offering the option with their usual caseload of patients with cancer. “I feel like we’re opening the floodgates, but I’m trying to do it carefully,” Shapiro said. “Considering how prevalent arthritis is and our aging population, there’s a lot of opportunity to expand, but I think we have to do it thoughtfully and really educate referring doctors.”

Ayesha, Kirschner, McGibbon, and Shapiro disclosed having no disclosures. Reznik reported consulting with Varian Medical Systems.

Tara Haelle is a Dallas-based science and health journalist.