Non-steroidal anti-inflammatory medication (NSAID) therapy is a mainstay treatment for joint pain and painful musculoskeletal disorders. Though this form of systemic therapy is highly effective, it causes substantial side effects including gastritis and gastric ulcer disease, renal impairment, hypertension, and thrombotic events. These types of oral medications are utilized by millions of Americans on a fairly regular basis in both over-the-counter preparations and prescription compounds. In recent years, topical preparations of NSAIDs have been used for localized pain as an alternate to oral administration with reported good analgesic efficacy. For example, they are often used for knee pain. There is little systemic absorption of NSAIDs with topical administration, and consequently less likelihood of systemic side effects.

Though much less studied than oral NSAIDs, topical NSAID preparations are currently prescribed for a variety of arthritic and musculoskeletal types of pain. The best-studied commercially available products are diclofenac 1% compounds. Higher concentrations presumably provide higher tissue concentration leading to better and longer pain relief, along with a more prominent anti-inflammatory effect.

The investigators will therefore compare the efficacy of available topical diclofenac 1% gel to that of diclofenac 8% cream. Specifically, the investigators propose to test the hypothesis that efficacy of topical diclofenac 8% exceeds that of diclofenac 1%, without any increase in systemic toxicity.

One hundred six patients presenting to the Cleveland Clinic Pain Management Department for the treatment of knee pain will be randomly assigned to topical diclofenac cream 8% or diclofenac gel 1%, with the designated medication applied the symptomatic area of the knee over 6 weeks. Investigators will be blinded to treatment, and will evaluate pain relief and functional/disability status.

Inclusion Criteria:

• Acute and chronic knee pain, along with postoperative knee pain lasting at least two months.

Exclusion Criteria:

• Patients will be excluded if deemed inappropriate for application of topical medication therapy by the treating physician. This will include adult patients with diffuse (non-localized) pain disorders and those likely to need knee surgery during the treatment period.
• Patients with knee infection, open knee wounds, or acute knee skin lesions will be excluded.
• Patients with diclofenac or wheat or gluten allergies will also be excluded.