bmi > 30

no clinically detectable knee effusion

clinical or radiographic evidence of knee osteoarthritis or inflammatory arthritis

must be referred to the pain clinic for treatment

history of surgery on the affected knee

evidence of untreated systemic infection or systemic immunocompromise

evidence of cutaneous infections near the study knee injection site

patients on warfarin with an inr > 3.0

patients on oral antiplatelet or anticoagulant medications will be excluded if they have documented evidence of renal insufficiency (gfr < 60)

history of iodinated contrast allergy or significant reaction to corticosteroids or lidocaine