Genicular Artery Embolization and Genicular Nerve Ablation

Genicular Artery Embolization and Genicular Nerve Ablation: Nonsurgical Options for Knee Osteoarthritis Pain

What is knee osteoarthritis?
Knee osteoarthritis (OA) affects up to 30% of adults over 45 and more than half of adults over 75, causing pain, stiffness, and swelling that interferes with daily life. More than half of people with knee OA will eventually be offered a total knee replacement, but not everyone is ready for surgery, wants surgery, or is medically able to have it. For those patients, interventional radiology offers two nonsurgical, image-guided treatments: genicular artery embolization (GAE) and genicular nerve ablation (GNA).

How do interventional radiologists treat knee pain?
Osteoarthritis involves ongoing low-grade inflammation in the joint lining. That inflammation drives abnormal new blood vessel growth (neovascularization), and those new vessels bring new nerve fibers into joint tissue that isn't normally well-supplied with either. This is a major driver of chronic OA pain. Genicular artery embolization (GAE) targets these blood vessels to both treat the pain and prevent the progression of OA. During this procedure, an interventional radiologist threads a microscopic catheter through a small puncture in the wrist or groin into the arteries feeding the inflamed tissue and injects tiny particles to reduce blood flow to it, calming the inflammation at its source rather than just the pain it causes. Only the inflamed blood vessels are targeted, sparing the normal vasculature of the joint.

For patients who have bone-on-bone articulation, the main pain driver shifts from an inflamed joint capsule to the nerve fibers of the bone. Therefore, the sensory nerves themselves are targeted to disrupt the pain signals that travel up from the knee. During the genicular nerve ablation (GNA) procedure, the interventional radiologist uses targeted heat to temporarily disrupt the nerve fibers to block the transmission of pain. 

GAE was originally developed to control recurrent bleeding into the knee joint (hemarthrosis) after total knee replacement, a use that has nearly two decades of track record and reported success rates around 86%. While treating that bleeding, physicians noticed patients' chronic pain and swelling also improved, which led to GAE being studied directly for osteoarthritis treatment. 

Published data shows GAE reduces pain by 50 - 67% within three to 12 months, with no long-term impact on bone health or future joint replacement.  The most common GAE side effect is temporary skin discoloration at the treated area, typically resolving in three to four weeks. For GNA, randomized trials show roughly 75% of patients achieve at least 50% pain reduction, with relief lasting up to 24 months after a single treatment.

Who is a candidate?
GAE may be right for you if you have knee pain and swelling that hasn't responded to three to six months of conservative treatment (NSAIDs, physical therapy, injections), mild-to-moderate OA with evidence of inflammation on imaging, and no active infection, uncontrolled bleeding disorder, severe vascular disease, or significant kidney disease.

GNA may be right for you if you have chronic OA knee pain (or persistent pain after a prior knee replacement) and respond well to a diagnostic nerve block — a short-acting injection used to confirm the right nerves before committing to ablation.

Both are best suited to patients who want to avoid or delay total knee replacement, or aren't yet candidates for surgery. Patients with severe, "bone-on-bone" arthritis generally see less benefit from either procedure and are often better served by a conversation about knee replacement. We work closely with our orthopedic colleagues to make sure you have a clear path forward either way. The best way to know which option fits you is a consultation with one of our interventional radiologists.

What to Expect
You'll start with a consultation to review your symptoms, prior treatments, and imaging (we'll order updated X-rays or an MRI if needed). Based on the findings, your physician will recommend either GAE or GNA. 

Our procedures are all done with moderate (conscious) sedation. For the embolization procedure, the interventionalist threads a small catheter through your groin following local anesthesia and uses live X-ray guidance to direct this catheter into the inflamed vasculature. Once localized, these vessels are selectively embolized to reduce inflammation while maintaining blood flow to your joint capsule.

For the ablation procedure, the interventionlist places four needles around your knee where the sensory nerves travel and, after sufficient numbing, uses targeted heat to disrupt those fibers. 

All our patients go home the same day. Recovery involves mild soreness or swelling for one to two weeks. Temporary skin discoloration is common and expected after GAE. GNA relief is often noticeable within days to weeks. GAE works more gradually, with improvement typically building over one to three months.