LDRT uses very small, targeted doses of radiation to reduce inflammation in joints affected by osteoarthritis. The treatment is painless, requires no anesthesia, and each session takes only a few minutes. A typical course involves 6 treatments over 3 weeks.
LDRT works by calming the overactive immune cells in your joints that cause inflammation and pain. It does not cure osteoarthritis, but clinical studies show it can provide significant pain relief lasting 6–24 months from a single course.
What changes: inflammatory behavior. What does not: cartilage and bone are not rebuilt.
When people hear radiation, they often imagine cancer treatment and cell killing. Low-dose radiotherapy for arthritis uses a much smaller dose and a different biological goal.
In an inflamed joint, the synovial lining and its tiny blood vessels help recruit immune cells. Those cells release cytokines and other signals that can keep the tissue irritated and amplify pain.
At low doses, radiation appears to change that local conversation. Experimental studies show less immune-cell adhesion to the vessel wall, less migration into tissue, and shifts in macrophage polarization and signaling. The full pathway is still being worked out.
It does not rebuild cartilage or erase osteoarthritis on an X-ray. Instead, over the following weeks, the synovium may become less reactive and send fewer pain-amplifying signals.
The simplest way to remember it is this: low-dose radiotherapy is not trying to destroy the joint. It is trying to turn down local inflammation so the joint can hurt less.
LDRT may be appropriate for patients with osteoarthritis who have not found adequate relief from other treatments such as physical therapy, medications, or injections. A radiation oncologist can determine if LDRT is right for you.
Watch: what a course of treatment is like — 1-minute narrated video. The people shown are illustrative. Ask your own care team what to expect at their center.
Here's what low-dose radiation therapy for knee arthritis usually looks like. First, you'll meet with a radiation oncologist. You'll review your symptoms, your imaging, and whether treatment makes sense for you.
During that visit, the clinician also examines your knee: where it hurts, how it moves, and how your symptoms affect everyday function.
Next comes simulation: a short CT scan while a simple support keeps your leg comfortable and still. Nothing is being treated that day. This scan is simply the map for your care.
On treatment days, the therapist settles you into that same position. Then the therapist steps outside while continuing to watch and speak with you.
The gantry may move around your knee, but it never touches you. You won't feel the radiation, and it won't make you radioactive. Each session takes only a few minutes. Most people have six short visits in total.
Then you get up and go home. Most people drive themselves and get back to their day.
A multidisciplinary group of physicians has published Appropriate Use Criteria (AUC) for low-dose radiation therapy in osteoarthritis. This cross-specialty consensus offers providers shared, evidence-based guidance on when LDRT may be a reasonable option to consider. Read the published criteria.
If you think LDRT could be worth discussing, use our LDRT provider directory to find a radiation oncology center near you.
Medically reviewed by: Robert Warren Floyd, M.D., Ph.D. — Resident Physician, Radiation Oncology, The University of Texas MD Anderson Cancer Center. Last reviewed: September 8, 2026. Independent personal project — not affiliated with or endorsed by MD Anderson Cancer Center. Funding & independence disclosure.
This content is for education only and is not medical advice. Always consult a qualified healthcare provider for diagnosis and treatment decisions.