What is genicular artery embolization?
In an arthritic knee, the lining of the joint — called the synovium — becomes inflamed and grows new, abnormal blood vessels (a process called neovascularity). Those new vessels feed ongoing inflammation and pain. GAE targets that problem at the root: a tiny catheter is guided into the small genicular arteries around the knee, and microscopic particles are injected to gently reduce blood flow to the inflamed tissue. Healthy circulation to the joint is preserved.2
The result is less inflammation, less synovial irritation, and less pain. The procedure is FDA-cleared for use of standard embolic microspheres, performed in the same way embolization is used for fibroids, prostate enlargement, and other conditions where image-guided arterial therapy has become standard.
Where GAE fits in the knee pain ladder
GAE is for patients who have moved past first-line treatments — NSAIDs, cortisone, viscosupplementation (gel injections), physical therapy — but aren’t yet candidates for, or aren’t ready for, total knee replacement. It is one tool in a coordinated plan with your pain management, orthopedic, rheumatology, and physiatry teams.
How the procedure works
GAE is performed in a hospital interventional suite under local anesthesia with light sedation. Through a small needle access in the wrist (radial artery) or groin (femoral artery), a thin catheter is advanced under live X-ray imaging to the knee. Selective angiography maps the abnormal vessels feeding the inflamed synovium. A microcatheter is then used to deliver tiny calibrated particles — most commonly Embozene microspheres or Imipenem-cilastatin — super-selectively into those abnormal vessels.3
Healthy arteries supplying skin, muscle, and bone are preserved. Total procedure time is typically 60 to 90 minutes. Most patients are discharged the same day and resume normal activity quickly.
Who is a good candidate?
GAE is most useful when chronic knee pain has not responded to conservative treatment but the joint is not yet damaged enough to need replacement. You may be a candidate if any of the following apply:
- Mild to moderate knee osteoarthritis on weight-bearing X-ray (Kellgren-Lawrence grade I–III)
- Conservative treatments have stopped working — physical therapy, NSAIDs, cortisone injections, or gel (hyaluronic acid) injections are no longer giving you adequate relief
- You’re not yet ready for, or not a surgical candidate for, total knee replacement — whether for medical reasons, weight, or personal preference
- You’d like to avoid long-term opioid pain medication
- Persistent pain or recurrent hemarthrosis (bleeding inside the joint) after a previous knee replacement, which can sometimes be related to abnormal vessels in the joint lining4
The decision is always made together with your pain management, orthopedic surgeon, or rheumatology team, depending on who is helping manage your knee.
A second use: recurrent hemarthrosis after knee replacement
Beyond osteoarthritis pain, GAE has a second, well-established role: treating recurrent hemarthrosis — repeated bloody effusions — after a total knee arthroplasty. After knee replacement, the joint lining can develop fragile, abnormal vessels (hypervascular synovial proliferation) that bleed with normal activity. Patients can develop a pattern of swelling, pain, stiffness, and the need for repeated joint aspirations to drain blood. Anticoagulation (such as warfarin or a DOAC) and bleeding disorders (including hemophilic arthropathy) can compound the problem.
Traditional options have included repeated aspirations, synovectomy, radiosynovectomy, or revision arthroplasty — all with their own challenges. GAE offers a far less invasive solution: super-selective embolization of the bleeding vessels through the same approach used for osteoarthritis. Published case series report durable resolution of recurrent hemarthrosis after a single GAE session in most patients, often avoiding revision surgery entirely.4
What the research shows
The largest randomized data come from the GENESIS and GENESIS 2 trials, in which patients undergoing GAE for moderate knee osteoarthritis showed significant reductions in pain and improvement in function compared with sham or conservative care, with benefits maintained over follow-up.2 Multiple subsequent series have shown sustained pain relief lasting beyond a year in selected patients, with a safety profile comparable to other small-vessel embolization procedures performed daily by interventional radiologists.3
Who performs GAE
Genicular artery embolization is performed by interventional radiologists. Success depends on careful angiographic mapping of small genicular arteries and super-selective delivery of the embolic material — both core skills of the specialty. At Florida Interventional Specialists, every GAE case is delivered under direct image guidance and integrated into your broader plan of care across pain management, orthopedics, rheumatology, and physiatry.
References
- Deshpande BR, Katz JN, Solomon DH, et al. The number of persons with symptomatic knee osteoarthritis in the US: impact of race and ethnicity, age, sex, and obesity. Arthritis Care Res (Hoboken). 2016;68(12):1743–1750.
- Little MW, Gibson M, Briggs J, et al. Genicular artEry embolizatioN in patiEnts with oSteoarthrItis of the Knee (GENESIS) using permanent microspheres: interim analysis. Cardiovasc Intervent Radiol. 2021;44(6):931–940.
- Bagla S, Piechowiak R, Hartman T, et al. Genicular artery embolization for the treatment of knee pain secondary to osteoarthritis. J Vasc Interv Radiol. 2020;31(7):1096–1102.
- Bagla S, Rholl KS, Sterling KM, et al. Geniculate artery embolization in the management of spontaneous recurrent hemarthrosis of the knee: technique and outcomes. J Vasc Interv Radiol. 2013;24(3):439–442.
- Okuno Y, Korchi AM, Shinjo T, et al. Transcatheter arterial embolization as a treatment for medial knee pain in patients with mild to moderate osteoarthritis. Cardiovasc Intervent Radiol. 2015;38(2):336–343.
Frequently asked questions
What is genicular artery embolization?
GAE is an image-guided procedure that uses tiny particles to reduce blood flow to abnormal vessels supplying the inflamed lining of an arthritic knee. Less inflammation means less pain. The procedure is same-day, opioid-free, and performed under local anesthesia with light sedation.
How is GAE different from a cortisone or gel injection?
Cortisone (corticosteroid) and gel (hyaluronic acid/viscosupplementation) injections deliver medication into the knee joint and tend to give shorter-duration relief. GAE addresses a different problem — the abnormal new blood vessels that grow in arthritic joints and feed chronic synovial inflammation. By targeting those vessels, GAE can provide durable relief that often lasts well beyond what injections offer.
How is GAE different from COOLIEF or genicular nerve ablation?
Both treatments target chronic knee pain that has not responded to conservative care, but they work in different ways. COOLIEF (cooled radiofrequency ablation) interrupts the small sensory nerves that carry pain signals from the knee. GAE reduces blood flow to the inflamed tissue producing those pain signals in the first place. Some patients are good candidates for one and not the other, and some can benefit from both at different times.
Can GAE be used to treat recurrent hemarthrosis after a knee replacement?
Yes. Recurrent hemarthrosis — repeated bloody effusions inside the knee — after total knee arthroplasty is a well-established indication for genicular artery embolization. The cause is usually hypervascular synovial proliferation, where the joint lining develops fragile abnormal vessels that bleed with normal activity. GAE targets those vessels and shuts down the bleeding source. Published case series report durable resolution of recurrent hemarthrosis after a single GAE session in most patients, often avoiding the need for revision surgery.
Will I still need a knee replacement eventually?
GAE doesn’t replace, repair, or change the underlying arthritis. It’s a pain treatment. For some patients it postpones knee replacement; for others — especially those who are not surgical candidates — it may be a long-term pain management strategy. Whether and when knee replacement makes sense for you is decided together with your orthopedic surgeon.
How long does the relief last?
Improvement typically begins in the first few weeks and continues to build through 3 to 6 months. Published series have reported sustained pain relief beyond one year. The procedure can be safely repeated when symptoms return.
Is the procedure painful?
GAE is performed under local anesthesia with light sedation. Most patients describe pressure rather than pain. Mild soreness or bruising at the small needle access site is common for a few days afterward and is typically managed with over-the-counter medication — no opioids required.
Who performs GAE?
GAE is performed by interventional radiologists. Success depends on careful angiographic mapping of the small genicular arteries and super-selective delivery of the embolic material — both core skills of the specialty.
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