A report from Buenos Aires, Argentina
Geniculate artery embolization (GAE) is a promising, minimally invasive therapy that that may change the way we look at pain and palliation. While early studies have shown significant and lasting symptom relief in patients with mild to moderate knee osteoarthritis (OA), we are still early in our exploration of this potential.
The rationale for GAE in patients with OA is based on the idea that neovascularization occurs where there is chronic inflammation. In patients with OA, chronically inflamed synovium usually results from a combination of altered biomechanics, joint trauma, age, obesity and an immune/inflammatory mediated response. Cytokines such as vascular endothelial growth factor (VEGF) are released that induce angiogenesis. The newly formed blood vessels grow into the cartilage, synovium and adjacent bone, bringing with it new sensory nerve fibers. This neovascularity is felt to perpetuate more inflammation, cartilage and bone destruction, as well as development of osteophytes. It is postulated that by embolizing the abnormal increased vasculature in the inflamed synovium, the intricate relationship between angiogenesis, chronic inflammation and pain is disrupted, thereby decreasing symptoms and possibly delaying further joint derangement.1
A small series led by Yuji Okuno, MD, PhD,2 in 14 patients with painful knee OA was the first manuscript to describe this technique. Particulate embolization was performed with either an antibiotic or a 75 micron spherical embolic in the region of palpable pain, after identifying an area of synovial hypervascularity. Overall, patients experienced a significant reduction in knee pain and disability. Dr. Okuno and his team have also published a similar experience in the treatment of elbow tendinopathy and shoulder capsulitis.
In an effort to drive further study on GAE, a South American pilot study has been initiated between the authors of this article and Ricardo Garcia-Monaco, MD, at Hospital Italiano in Buenos Aires, Argentina. Thus far, five patients with intractable knee pain have undergone GAE using 75 micron spherical embolic in the region of palpable tenderness. Patients also underwent preoperative MRI with contrast to evaluate for areas of increased synovial enhancement. Continued enrollment and long-term assessment of pain control is ongoing.
In the United States, Dr. Bagla and Ari Isaacson, MD, have received approval for an Investigational Device Exemption study for GAE. This single-arm, 20-patient study is expected to initiate enrollment in fall 2016 at University of North Carolina at Chapel Hill. The endpoints for this study will include reduction in pain, disability and requirement for escalation of therapy.
With more than 25 million people in the United States suffering from osteoarthritis (OA), interventional radiologists are poised to make a potentially large impact on the treatment of pain.
References
- Walsh DA. Angiogenesis and arthritis. Rheumatology 1999; 38:103–112.
- Okuno Y, Korchi AM, Shinjo T, Kato S. Transcatheter arterial embolization as a treatment for medial knee pain in patients with mild to moderate osteoarthritis. Cariovasc Intervent Radiol 2015; 38:336–343.
