Treatment of Knee Pain With Topical Diclofenac Cream 8% or Diclofenac Gel 1%

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.