Minimally invasive surgery that blocks abnormal blood vessels around the knee may provide long-term symptom relief for osteoarthritis patients, according to a new study published June 16 in the journal Arthritis. RadiologyJournal of the Radiological Society of North America (RSNA).
Osteoarthritis is the most common type of arthritis and a leading cause of disability worldwide. This condition can cause joint inflammation, stiffness, reduced mobility, and pain caused by sensory nerves. The World Health Organization estimates that more than 365 million adults worldwide have knee osteoarthritis.
“For many patients with knee osteoarthritis, there is a major gap in today’s treatment,” says Dr. Florian Nima Fleckenstein, Deputy Director of the Interventional Radiology Campus Mitte, Charité University Berlin. “Conservative measures such as intra-articular injections no longer provide sufficient relief, and joint replacement surgery is not an option for medical or personal reasons.”
A new approach to knee osteoarthritis pain
This treatment, known as knee embolization (GAE), is a new non-surgical procedure designed to target abnormal blood vessels that develop around arthritic knee joints. These excess blood vessels are thought to contribute to ongoing inflammation and pain.
During this procedure, an interventional radiologist uses a thin catheter to reach the affected blood vessels and inject microparticles that block blood flow. By blocking these abnormal blood vessels, this treatment aims to reduce inflammation and relieve pain without surgery.
In this study, researchers evaluated GAE performed using rapidly absorbed gelatin-based microspheres. These specially designed spherical particles are tailored by size and dissolve within hours of delivery. The research team proposed that this material could combine some of the benefits of both temporary and permanent embolic agents while avoiding some of their drawbacks.
“GAE is an entirely new treatment that targets the abnormal hypervascularity around the joints and thus modulates the pathological neurovascular environment,” said Dr. Fleckenstein. “By reducing both inflammation and pain, GAE using absorbable microspheres may be the first treatment to alter the course of the disease and slow its progression.”
Study of nearly 200 patients
This prospective, single-center study enrolled 194 patients with osteoarthritis-related knee pain, including 114 women and 80 men. All participants failed to obtain sufficient symptom relief after at least 3 months of conservative treatment, including physical therapy, anti-inflammatory drugs, and intra-articular injections.
The median age of participants was 69 years, and the median BMI was 28.4.
“We believe these results have real weight because they come from real-world data,” Dr. Fleckenstein said. “With this broad and comprehensive study design, our participants are exactly the patients physicians encounter every day in their practice.”
All patients underwent GAE using absorbable microspheres from July to November 2024. Forty-five participants (23%) had both knees treated, with the second procedure performed within 4 weeks of the first procedure.
The researchers performed a total of 239 GAE procedures. Treatment was performed using image (fluoroscopic) guidance. All procedures were technically successful. No moderate or severe adverse events occurred, and only 6.7% of participants experienced mild reactions that resolved spontaneously.
Significant pain relief and increased mobility
The researchers assessed outcomes before treatment and at 6 weeks, 3 months, 6 months, and 12 months after treatment. The 6-month evaluation was performed directly by an orthopedic surgeon.
Follow-up rates remained high throughout the study, reaching 94% (183/194) at 6 weeks, 89% (172/194) at 3 months, 89% (171/194) at 6 months, and 79% (154/194) at 12 months.
“In our cohort, there was a significant reduction in pain and a significant improvement in function, including sports, recreation, and daily living,” Dr. Fleckenstein said. “Most importantly, their quality of life has improved significantly.”
The pain level improved immediately and continued to improve over time. On the numerical rating scale (0 to 10 scale of pain intensity), the median score decreased from 7 before treatment to 4 after 6 weeks and then to 3 at both 6- and 12-month follow-up, indicating sustained relief throughout the year.
Patients also showed improvement in all categories of knee injury and osteoarthritis outcome scores.
The median daily activities score increased from 53 to 71.5, and the sports and recreation score increased from 15 to 36. Osteoarthritis-related symptoms improved from 51 to 68. The pain score increased from 44 to 65 (0 indicating extreme knee pain and 100 indicating no pain at all). Quality of life score improved from 19 to 40.
Most patients experience meaningful improvement
Previous studies have shown that a decrease of 2.0 points or more in the Numerical Rating Scale pain score and a 10 or more point increase in the Knee Injury and Osteoarthritis Outcome Score subscore represents a clinically meaningful improvement, known as the minimal clinically important difference.
At 12-month follow-up, 80% of participants exceeded that threshold based on Numerical Rating Scale pain scores.
“Our study shows that GAE using rapidly resorbable gelatin-based microspheres is a safe, minimally invasive treatment that provides meaningful pain relief and functional improvement for at least 12 months in participants with osteoarthritis-related knee symptoms,” said Dr. Fleckenstein. “By embolizing diseased blood vessels, we can normalize the structure of the blood vessels and, in turn, the neural structure of the knee.”
Dr. Fleckenstein said this study is the largest body of evidence to date investigating GAE using rapidly resorbable microspheres in approximately 200 patients.
“This allows us to talk about safety and efficacy with real confidence,” he said. “For the right patient, it means permanent symptom relief with a single, minimally invasive procedure, making it a meaningful new option between injections and joint replacement surgery.”
The study, Genital artery embolization using rapidly absorbable gelatin-based microspheres for osteoarthritis-associated knee pain, was conducted by Dr. Fleckenstein and colleagues Dina David, MD, Paolo Garducci, MD, Tazio Maretzke, MD, Stefan Ohme, MD, Lynn Janet Savic, MD, Timo Alexander Auer, MD, and Bernhard Gebauer, MD. Doctors of Medicine, Tobias Winkler, MD, Federico Collettini, MD
