OSTEOARTHRITIS (OA) of the knee affects 6.1% of the US adult population aged 30 years and older1 and is the leading cause of such mobility disabilities as difficulty walking or climbing stairs.2 Treatment for OA has been frustrating. Pharmacologic and nonpharmacologic therapies including nonsteroidal anti-inflammatory drugs (NSAIDs), analgesics, and exercise have shown efficacy, but when disease advances to the point of severe functional impairment and ongoing pain, total knee replacement is the sole remaining therapy. Notwithstanding the availability of this surgery, for many patients with this chronic disease, symptoms can be stubborn, and the disability associated with the pain, stiffness, and limited motion can diminish quality of life. New efficacious therapies are badly needed.