Inclusion Criteria:  Patients between ages 18 and 75 with moderate/severe knee pain secondary to primary osteoarthritis. Moderate/severe pain will be defined as pain 30 mm to 100 mm on the Visual Analog Pain Scale (where 0 denotes 'no pain' and 100 mm denotes worst pain imaginable') Grade 1, 2, or 3 osteoarthritis on the Kellgren-Lawrence grading scale on knee x-ray in the last 6 months Pain must be refractory to 3 months of medical management (which may include a combination of oral analgesics, intraarticular steroids, viscosupplementation, opioid therapy, etc) Patients willing and able to consent to the study  Exclusion Criteria:  Kidney dysfunction defined as an estimated GFR < 60 mL/min Acute knee injury Current local infection Prior ipsilateral knee replacement surgery Infectious or inflammatory arthritis History of contrast allergy resulting in anaphylaxis INR (International Normalization Ratio) > 1.6 Platelets < 50,000 Significant atherosclerosis that would limit angiography Active malignancy Active pregnancy Appropriate candidate for knee replacement surgery determined by clinical and physical examination Recent within 3 months, or active cigarette user