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.