Genicular Artery Embolization with Resorbable Microspheres Delivers Lasting Knee Osteoarthritis Pain Relief, Study Shows
Key Insights
A prospective single-center study of 194 patients found genicular artery embolization (GAE) using rapidly resorbable gelatin-based microspheres (search) provided significant and sustained knee osteoarthritis (search) pain relief for at least 12 months.
Median pain scores on the Numeric Rating Scale dropped from 7 before treatment to 3 at both 6- and 12-month follow-ups, with 80% of participants achieving clinically meaningful improvement at one year.
Every procedure was technically successful with no moderate or severe adverse events; only 6.7% of participants experienced mild, self-resolving reactions.
A new minimally invasive procedure that targets abnormal blood vessels around arthritic knee joints has demonstrated significant, lasting pain relief and functional improvement in a large real-world study, offering a potential bridge between conservative treatments and total joint replacement for millions of patients.
The procedure, known as genicular artery embolization (GAE), uses rapidly resorbable gelatin-based microspheres (search) to block excess blood vessels believed to drive inflammation and pain in osteoarthritic knees. In a prospective single-center study of 194 patients conducted at Charité – Universitätsmedizin Berlin, researchers found that pain relief was both rapid and durable, with benefits sustained through 12 months of follow-up.
"For many patients with knee osteoarthritis (search), there is a real treatment gap today," said Florian Nima Fleckenstein, M.D., deputy head of Interventional Radiology Campus Mitte at Charité and lead author of the study. "Conservative measures such as intra-articular injections no longer provide sufficient relief, but joint replacement is not an option for medical or personal reasons."
A Growing Unmet Need
Osteoarthritis is the most common type of arthritis and a major cause of disability worldwide. The World Health Organization estimates that more than 365 million adults globally live with knee osteoarthritis (search). The condition leads to joint inflammation, stiffness, reduced mobility, and pain caused by sensory nerves.
Current treatment options span a wide spectrum, from medications and physical therapy to steroid injections and, ultimately, total knee replacement. Yet for many patients, a significant gap exists between failing conservative therapies and being ready or eligible for major surgery.
"GAE is a promising minimally invasive procedure that may fill that spot for people who have failed conservative treatments but are not yet ready to have a major surgery," said Leigh Casadaban, MD, MS, assistant professor of radiology at the University of Colorado Anschutz School of Medicine (search).
How GAE Works
During the GAE procedure, an interventional radiologist makes a small incision in the crease of the leg and threads a thin catheter through the femoral artery under fluoroscopic guidance. When the catheter reaches the genicular arteries supplying the inflamed joint lining, the physician injects tiny calibrated particles that block blood flow to these abnormal vessels. By shutting down pathological hypervascularity, the treatment aims to reduce inflammation and modulate the neurovascular environment contributing to pain.
The procedure takes approximately one to two hours under conscious sedation. Patients are observed for a few hours afterward and discharged the same day with instructions to rest for several days.
"GAE is a whole new treatment regimen that targets abnormal hypervascularity around the joint and, in turn, modulates the pathological neurovascular environment," Dr. Fleckenstein said. "By reducing both inflammation and pain, GAE with resorbable microspheres may be the first procedure that alters the course of the disease, slowing its progression."
The gelatin-based microspheres (search) used in this study are designed to dissolve within hours after delivery, potentially combining advantages of both temporary and permanent embolization agents while avoiding their respective drawbacks.
Robust Real-World Evidence
The study enrolled 194 patients — 114 women and 80 men — with a median age of 69 years and a median body mass index of 28.4. All participants had failed to achieve adequate relief after at least three months of conservative treatment, including physiotherapy, anti-inflammatory medications, and intra-articular injections.
"We believe these results carry real weight because they come from real-world data," Dr. Fleckenstein said. "With this broad, inclusive study design, our participants are exactly the patients that physicians encounter every day in their practices."
All patients underwent GAE between July and November 2024. Forty-five participants (23%) received treatment in both knees, with the second procedure performed within four weeks of the first. In total, researchers carried out 239 GAE procedures, and every single procedure was technically successful.
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). The six-month evaluation was conducted in person by an orthopedic surgeon.
Sustained Pain Relief and Functional Gains
Pain levels improved quickly and continued to improve over time. On the Numeric Rating Scale, a 0-to-10 measure of pain intensity, the median score fell from 7 before treatment to 4 at six weeks, and further to 3 at both the 6- and 12-month follow-ups — indicating sustained relief throughout the year.
Patients also showed improvement across every category of the Knee Injury and Osteoarthritis Outcome Score (KOOS). Median scores for daily activities increased from 53 to 71.5, while sports and recreation scores rose from 15 to 36. Osteoarthritis-related symptoms improved from 51 to 68. Pain scores increased from 44 to 65, where 0 indicates extreme knee pain and 100 indicates no pain at all. Quality of life scores improved from 19 to 40.
"In our cohort, we saw a significant drop in pain and a significant increase in function, including sports and recreation and daily activity," Dr. Fleckenstein said. "Most importantly, their quality of life significantly increased."
Previous research has established that a reduction in Numeric Rating Scale pain score of at least 2.0 points and an increase of at least 10 points in KOOS sub-scores represent clinically meaningful improvements — the minimum clinically important difference. At the 12-month follow-up, 80% of participants exceeded that threshold based on their pain scores.
Safety Profile
No moderate or severe adverse events occurred across all 239 procedures. Only 6.7% of participants experienced mild reactions that resolved on their own without intervention.
"Our study demonstrates that GAE using rapidly resorbable gelatin-based microspheres (search) is a safe, minimally invasive therapy that provides meaningful pain relief and functional improvement in participants with osteoarthritis-related knee symptoms for at least 12 months," Dr. Fleckenstein said. "By embolizing the pathological vessels, we're able to normalize the vessel structure — and, in turn, the neuronal structure of the knee."
A Growing Body of Evidence
The Berlin study represents the largest body of evidence to date examining GAE with rapidly resorbable microspheres. Longer-term data from other centers have also been encouraging: four-year data published in Japan suggests pain relief can last for that duration following a single outpatient procedure, while two-year U.S. data similarly shows durable responses.
"This lets us speak about safety and efficacy with real confidence," Dr. Fleckenstein said. "For the right patient, it can mean lasting relief from a single, minimally invasive procedure — a meaningful new option between injections and joint replacement."
The GAE procedure originated in Japan just over a decade ago and has since grown considerably across the globe. The FDA has granted breakthrough device status for multiple GAE-related devices in the U.S. since 2021. While currently focused on knee osteoarthritis (search), researchers note the approach is expanding to other joint conditions, including frozen shoulder, tennis elbow, and plantar fasciitis.
The study, "Genicular Artery Embolization Using Rapidly Resorbable Gelatin-based Microspheres (search) for Osteoarthritis-related Knee Pain," was conducted by Dr. Fleckenstein and colleagues Dina David, M.S., Paolo Garducci, M.D., Tazio Maleitzke, M.D., Stephan Oehme, M.D., Lynn Jeanette Savic, M.D., Timo Alexander Auer, M.D., Bernhard Gebauer, M.D., Tobias Winkler, M.D., Ph.D., and Federico Collettini, M.D.