A Study of ABT-652 in Combination With a Nonsteroidal Anti-Inflammatory Drug (NSAID) in Adults With Osteoarthritis Pain of the Knee

Inclusion Criteria: * History of osteoarthritis (OA) of the knee joint and meeting American College of Rheumatology (ACR) Clinical and Radiographic criteria, * Currently taking nonsteroidal anti-inflammatory drugs (NSAIDs) and still experiencing pain as per the protocol requirements. * Willing to washout of analgesics and to follow treatment plan, visit schedules and study procedures. Exclusion Criteria: * Diagnosis of rheumatoid arthritis, autoimmune disorder, arthritis other than osteoarthritis involving the study joint, or other painful syndrome that could interfere with the assessment of pain at the study joint * Any cardiac, respiratory, neurological, psychiatric disorder or any other medical condition or illness that is not well controlled with treatment