Oral non-steroidal anti-inflammatory drugs (NSAIDs) are a recommended treatment for the symptoms of osteoarthritis of the knee. However, NSAIDs may cause a range of negative side effects, including stomach pain, heartburn, bleeding stomach ulcer, and liver or kidney abnormality. A topical NSAID may relieve pain and other symptoms of osteoarthritis of the knee, while minimizing the side effects common to oral NSAIDs. The purpose of this study is to determine the safety and effectiveness of a topical NSAID when used alone or when combined with an oral NSAID in the treatment of osteoarthritis of the knee.

During this 12-week study, patients will visit the study clinic 5 times. At the screening visit, the patient's demographic information, medical and medication history will be recorded and a physical examination performed. After washout of all NSAIDs/other analgesic medication, the patient will return for the baseline visit. During the treatment phase of the study, the patient will apply a topical solution to his/her osteoarthritic knee and take an oral study tablet. The patient may randomly receive active treatment with topical diclofenac, oral diclofenac, both, or neither (placebo). Follow-up clinic visits are conducted at 4, 8 and 12 weeks. Routine laboratory analyses are done at baseline, 4 and 12 weeks.

Inclusion Criteria:

• Primary osteoarthritis of the knee, verified radiographically
• Moderate flare of pain in the knee after washout of stable therapy
• If female, non-pregnant
• Ability to swallow moderately-sized tablets

Exclusion Criteria:

• Secondary osteoarthritis of the knee
• Major knee surgery at any time, or minor knee surgery in previous year
• Severe uncontrolled heart, liver or kidney disease
• Ulcer or bleeding from the stomach
• Corticosteroid use
• Fibromyalgia
• Skin disorder of the knee