fMRI Study of Expectancy on Acupuncture Treatment Outcomes in Knee OA

Inclusion Criteria: * Volunteers 40-70 years of age. * Meet the Classification Criteria of the American College of Rheumatology for osteoarthritis of the right and/or left knee for at least the past 3 months, as determined by the referring physician. * Radiographic evidence of Grade 2 or 3 knee OA using the Kellgren-Lawrence Scale. * Ability to read and understand English; English can be a second language provided that the patients feel they understand all the questions used in the assessment measures. Exclusion Criteria: * Any interventional procedure for knee pain, including corticosteroid injections (within 2 months) to the knee. * Prior acupuncture treatment for any condition. Because we are using a placebo needle as a control, acupuncture-naive patients are necessary to maximize the benefits of blinding and to control expectancy. * The intent to undergo surgery during the time of involvement in the study. * Presence of any illness or medication use that is judged to interfere with the trial. For example: skin irritations around the knee such as psoriasis; bleeding disorders or anticoagulant use that would be contraindications for acupuncture; diabetes due to the increased possibility of sensitivity to heat pain; and use of opiate medications and other substances of abuse that may influence the patient's experience of analgesia. (Due to the potential risk that prescription or non-prescription medication use can confound our results, we may perform a urine toxicology screen to verify patient's medication status during Session 1.) * Knee pain due to other causes, such as inflammation or malignancy, other pain disorders that may refer pain to the leg, OA of ipsilateral hip, diagnosis of rheumatoid arthritis (RA). * Non-ambulatory status. * History of cardiac, respiratory, or nervous system disease that, in the investigator's judgment, precludes participation in the study because of a heightened potential for adverse outcome. For example: asthma or claustrophobia. * Presence of any contraindications to fMRI scanning. For example: cardiac pacemaker, metal implants, fear of closed spaces, pregnancy. * Instability of pain rating within Session 1 or Session 2 of Experiment One or Visit 1 of Experiment Two.