New Treatment Provides Long-Term Relief from Knee Pain Caused by Osteoarthritis Without Surgery

A minimally invasive procedure that blocks abnormal blood vessels in the knee area could provide long-lasting relief for people with osteoarthritis. This is according to a new study published in Radiology, a journal of the Radiological Society of North America (RSNA).

A New Approach to Pain Caused by Knee Osteoarthritis

Osteoarthritis is the most common form of arthritis and one of the leading causes of disability worldwide. The condition can lead to joint inflammation, stiffness, limited mobility, and pain caused by sensory nerves. The World Health Organization estimates that more than 365 million adults worldwide suffer from knee osteoarthritis. “For many patients with knee osteoarthritis, there is currently a real treatment gap,” said Dr. Florian Nima Fleckenstein, MD, deputy head of Interventional Radiology at the Mitte Campus of Charité – Universitätsmedizin Berlin. “Conservative measures such as intra-articular injections no longer provide sufficient relief, yet joint replacement is not an option for medical or personal reasons.”

The treatment, known as genicular artery embolization (GAE), is a novel non-surgical procedure that specifically targets abnormal blood vessels that form around arthritic knee joints. It is believed that these excess vessels contribute to persistent inflammation and pain. This technique was originally developed by interventional radiologists and is intended specifically for patients whose symptoms persist despite physical therapy, pain medication, or injections, but who do not yet require a knee replacement or wish to avoid surgery. During the procedure, an interventional radiologist uses a thin catheter to reach the affected blood vessels and injects tiny particles that block blood flow to them. By occluding these abnormal vessels, the treatment aims to reduce inflammation and relieve pain without surgery.

This approach is based on the understanding that in osteoarthritis, it is not only the articular cartilage that is damaged, but inflammatory processes in the synovial membrane also play a significant role. As the disease progresses, new, abnormal blood vessels often form in the area of the affected joint. These vessels are frequently associated with the ingrowth of pain fibers and increased inflammatory activity. GAE addresses precisely this issue: By selectively occluding these pathologically altered vessels, the goal is to attenuate the inflammatory response and reduce pain transmission. The procedure is typically performed under local anesthesia. Through a small access point in the femoral or radial artery, a thin catheter is advanced to the so-called genicular arteries, which supply the knee. Contrast agents and imaging techniques are used to visualize the affected vessels. Microscopically small embolization particles are then injected to selectively reduce or block blood flow to these vessels. The surrounding healthy tissue is preserved as much as possible, since only the pathologically altered vessel segments are treated. Studies to date show promising results. Many patients report a significant reduction in pain as well as improved mobility and quality of life for months to years after the procedure.

For this study, the researchers evaluated a GAE performed using rapidly resorbable gelatin-based microspheres. These specially developed spherical particles are calibrated by size and dissolve within a few hours of administration. The team hypothesized that the material could combine some of the advantages of both temporary and permanent embolization agents while avoiding some of their disadvantages.” “GAE is a completely new treatment regimen that targets the abnormal hypervascularity around the joint and thereby modulates the pathological neurovascular environment,” said Dr. Fleckenstein. “By reducing both inflammation and pain, GAE with resorbable microspheres could be the first procedure to alter the course of the disease and slow its progression.”

Significant Pain Relief and Improved Mobility

The prospective, single-center study included 194 patients with osteoarthritic knee pain, including 114 women and 80 men. None of the participants had achieved adequate relief after at least three months of conservative treatment—including physical therapy, anti-inflammatory medications, and intra-articular injections. The median age of the participants was 69 years, and the median body mass index was 28.4. “We believe these results carry real weight because they are based on real-world data,” said Dr. Fleckenstein. “Thanks to this broad, inclusive study design, our participants closely resemble the patients that doctors encounter every day in their practices.”

All patients underwent an ARJ using the resorbable microspheres between July and November 2024. Forty-five participants (23%) received treatment on both knees, with the second procedure performed within four weeks of the first. In total, the researchers performed 239 ARJ procedures. The treatments were performed under imaging (fluoroscopic) guidance. Every procedure was technically successful. No moderate or severe adverse events occurred, and only 6.7% of participants experienced mild reactions that resolved on their own.

The researchers assessed the results before treatment and again six weeks, three months, six months, and twelve months afterward. The six-month follow-up was conducted in person by an orthopedic surgeon. Follow-up rates remained high throughout the study, reaching 94% at six weeks (183/194), 89% at three months (172/194), 89% at six months (171/194), and 79% at 12 months (154/194). “In our cohort, we observed a significant reduction in pain and a significant improvement in functional ability, including sports, leisure activities, and activities of daily living,” said Dr. Fleckenstein. “Above all, however, the patients’ quality of life has improved significantly.”

Pain scores improved rapidly and continued to improve over time. On the Numerical Rating Scale (a scale from 0 to 10 used to measure pain intensity), the median score dropped from 7 before treatment to 4 after six weeks and then to 3 at both the six-month and twelve-month follow-up visits, indicating sustained relief throughout the year. Patients also showed improvements in all categories of the “Knee Injury and Osteoarthritis Outcome Score.” Median scores for daily activities rose from 53 to 71.5, while scores for sports and leisure activities increased from 15 to 36. Osteoarthritis-related symptoms improved from 51 to 68. Pain scores rose from 44 to 65 (where 0 indicates extreme knee pain and 100 indicates complete freedom from pain). Quality-of-life scores improved from 19 to 40.

Most Osteoarthritis Patients Experienced a Significant Improvement

Previous studies have shown that a reduction in the pain score on the Numerical Rating Scale (NRS) by ≥ 2.0 points and an increase in the subscores of the “Knee Injury and Osteoarthritis Outcome Score” (KIOOS) by ≥ 10 points represent clinically significant improvements, referred to as the “minimum clinically important difference.” At the 12-month follow-up, 80% of participants exceeded this threshold, as measured by their pain scores on the Numerical Rating Scale (NRS).

“Our study demonstrates that GAE using rapidly resorbable gelatin-based microspheres is a safe, minimally invasive therapy that results in significant pain relief and functional improvement in participants with osteoarthritis-related knee symptoms over a period of at least 12 months,” said Dr. Fleckenstein. “By embolizing the pathological vessels, we can normalize the vascular structure—and thus also the neural structure of the knee.” According to Dr. Fleckenstein, the study, which included nearly 200 patients, represents the most comprehensive evidence base to date for investigating GAE with rapidly resorbable microspheres. “This allows us to speak with great confidence about safety and efficacy,” he said. “For the right patient, this can mean lasting relief through a single, minimally invasive procedure—a valuable new option between injections and joint replacement.”