Osteoarthritis Embolization

Background and indications

Genicular artery embolization (GAE) is an innovative treatment for osteoarthritis-related knee pain. The principle is based on the observation that abnormal neovascularization (neoangiogenesis) of the synovial membrane and peri-articular structures plays a key role in chronic inflammation and osteoarthritic pain. Embolization aims to reduce this pathological neovascularization and associated inflammation.

GAE is indicated for patients with moderate to severe knee osteoarthritis (Kellgren-Lawrence grades II-IV), resistant to conservative treatments (physiotherapy, analgesics, injections), who are not candidates for or do not wish to undergo knee replacement. It can also be offered for hip, shoulder, or elbow osteoarthritis.

Pre-procedure assessment

Assessment includes weight-bearing knee radiographs (Kellgren-Lawrence grade evaluation), knee MRI (assessment of synovitis, neovascularization, and cartilage status), and vascular workup. A pain questionnaire (VAS) and functional score (WOMAC or KOOS) are performed as baseline.

Procedure

Under local anesthesia, a microcatheter is introduced through the femoral artery. Under fluoroscopic guidance, the interventional radiologist selectively catheterizes the genicular arteries (medial, lateral, recurrent) and identifies areas of pathological neovascularization (synovial blush). Small microspheres (75 µm, Embozene or IPM type) are injected to occlude abnormal neovascularization while preserving normal joint vasculature. The procedure takes approximately 60 to 90 minutes.

Results and scientific evidence

The concept was developed by Dr. Yuji Okuno in Japan. His initial study of 72 patients with moderate to severe knee osteoarthritis showed significant pain reduction at 2 years, with mean VAS score decreasing from 74 to 26 mm (Okuno et al., CardioVascular and Interventional Radiology, 2017; DOI: 10.1007/s00270-017-1612-3).

The randomized sham-controlled GENESIS trial confirmed GAE superiority over sham procedure at 6 months for pain relief and functional improvement (Bagla et al., Radiology, 2022; DOI: 10.1148/radiol.212681). Clinical response rates are 70-85% at 12 months.

Risks and complications

Complications are rare: transient skin discoloration around the knee (5-10%, resolving within weeks), transient local pain (< 5%). Major complications (non-target embolization with skin necrosis) are exceptional (< 1%) with small particle use and super-selective catheterization.

Recovery

Return to normal activities is possible the following day. Pain improvement is progressive over 1 to 4 weeks, with maximum effect at 3-6 months. Physiotherapy is encouraged in parallel. Follow-up is scheduled at 1, 3, 6, and 12 months.

Practical information

The procedure is performed as an outpatient or short inpatient stay depending on the case. It is performed by a specialized interventional radiologist.