The goal of this study is to create a prospective registry (<100 patients) to show the effectiveness of the genicular artery embolization procedure overtime in reducing bilateral or unilateral osteoarthritic knee pain as measured by Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score.

Knee osteoarthritis (KOA) is a pervasive and debilitating disease, affecting over 15 million people in the US alone. Symptoms include pain, stiffness, and ultimately loss of joint function. Medical therapies are the mainstay of treatment as surgical joint replacement is typically reserved for advanced disease. Only half of patients treated by medical management with disease not severe enough to warrant surgery experience adequate pain relief, resulting in an estimated population of 3.6 million Americans who are left suffering. Genicular artery embolization (GAE) is a novel, minimally invasive treatment that uses radiologic techniques to catheterize pathologically hyperemic genicular arteries using live X-ray guidance with subsequent occlusion of these vessels using injected microspheres. GAE is performed to inhibit or blunt synovial inflammation thought to be a primary phenotype of KOA. Multiple small sized cohort studies have shown to significantly reduce pain associated with KOA. This procedure has been performed in the University of Chicago Medical Center and showed its effectiveness and safety. In this study, the investigators plan to establish a prospective database of patients undergoing GAE for KOA in order to further characterize its effectiveness with a longer follow-up and larger sample size. The investigators also hope to establish Magnetic Resonance Imaging (MRI) as an objective imaging biomarker for positive remodeling of the knee that occurs after GAE due to decreased synovitis. If the results of this study are positive, the investigators plan to conduct a definitive sham-controlled study to justify the use of GAE in medically refractory KOA and help provide a treatment option to the millions of people with this disease.

Inclusion Criteria:

• Patients aged >=18
• Bilateral or unilateral knee pain attributed to knee osteoarthritis (KOA). For bilateral KOA patients, the more severe knee will be permitted inclusion to the registry
• Grade 1-3 Osteoarthritis as diagnosed on standing weight-bearing knee radiographs per the Kellen-Lawrence Grading scale
• Knee pain >6 months refractory to conservative medical management (Nonsteroidal anti-inflammatory drugs, acetaminophen, etc.)
• Not eligible for surgical knee replacement or patient's personal preference to undergo Genicular Artery Embolization (GAE) for reasons such as minimally invasiveness of GAE

Exclusion Criteria:

• Active malignancy
• Active infection of the affected knee
• Platelets <50,000/uL, INR >2.0 (unless on anticoagulation that can be reversed or performing radial/pedal access without reversal)
• Corticosteroid injection of the affected knee within 3 months of enrollment
• Rheumatoid arthritis or other seronegative arthropathy
• Previous surgery (excluding arthroscopy) of the affected knee
• Grade 4 per Kellgren-Lawrence Grading Scale of the affected knee
• Pregnancy or expected pregnancy
• Glomerular Filtration Rate (GFR) <30
• Anaphylactic reaction to iodinated contrast
• Moderate to severe pain in other lower limb joints
• Body weight >400 lbs. (prohibiting safe angiography)
• Peripheral arterial disease of the treated extremity (Rutherford Grade 2 or greater)

Patients with medically refractory knee osteoarthritis

All IPD is de-identified when entered into the EDC. Results will not share IPD or PHI, rather the trends and calculations that are concluded based on data collected in the EDC.