Osteoarthritis (OA) is the most common form of arthritis and can cause pain, swelling, and reduced motion in the joints, which as a result can impact quality of life. It can occur in any joint, but usually affects the hands, knees, hips or spine. The purpose of this study is to determine the efficacy and safety of a topical nonsteroidal anti-inflammatory drug (NSAID) gel formulation in the treatment of osteoarthritis of the knee.