Knee pain can make everyday tasks like walking, bending, or getting into a car difficult. For people with osteoarthritis (OA), this pain is often long-lasting and hard to treat.
But a new study offers hope through a surprising method: gently stimulating a nerve through the ear.
Researchers at The University of Texas at El Paso (UTEP), in partnership with Harvard Medical School and Boston University, have tested a new way to reduce knee pain by targeting the vagus nerve.
Their early results, published in the journal Osteoarthritis and Cartilage Open, suggest that this approach could help relieve pain without the common side effects of traditional treatments.
Dr. Kosaku Aoyagi, a physical therapist and assistant professor at UTEP, led the study. He said his experience working with patients who suffer from knee pain inspired him to look for better treatment options.
While current therapies like medication or physical therapy offer only limited relief, they often assume that pain is caused directly by damage in the knee joint. Aoyagi’s approach is different—it focuses on how the brain and nervous system process pain signals.
At the center of this new method is the vagus nerve, a major part of the body’s parasympathetic nervous system. This system helps the body relax, rest, and recover, while its opposite—the sympathetic nervous system—prepares the body for stress or danger. In people with knee osteoarthritis, there may be an imbalance between these systems, which can worsen pain.
To correct this imbalance, the researchers used a device that sends gentle pulses to a branch of the vagus nerve located in the ear. The method is called transcutaneous auricular vagus nerve stimulation, or tVNS. In the pilot study, 30 participants with knee osteoarthritis used the device for 60 minutes during one session.
After the treatment, 11 of the 30 participants reported noticeable relief in their knee pain. While this is a small group, it’s an encouraging result, especially since the therapy is non-invasive and doesn’t involve drugs.
The treatment is also already approved by the U.S. Food and Drug Administration (FDA) for other conditions, including epilepsy and depression, which supports its safety.
Stacy Wagovich, interim dean of UTEP’s College of Health Sciences, praised the research as an important first step. She emphasized that with further testing, this technique could become a new tool for managing knee pain.
The study is still in its early stages, and the treatment is not yet available to the public. The next step is to run a larger randomized controlled trial. In that study, some participants will receive the tVNS treatment, while others will receive a placebo so that researchers can better measure the therapy’s true effect.
In summary, this innovative research shows that stimulating a nerve in the ear might help reduce knee pain by calming the body’s pain response system. While more studies are needed, this approach could one day offer people with knee osteoarthritis a safe, drug-free way to manage their pain and improve their quality of life.
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The research findings can be found in Osteoarthritis and Cartilage Open.
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