The effects of a topical analgesic and placebo in treatment of chronic knee pain.

Chronic knee pain is a prevalent health problem of old and middle age. The authors' objective was to determine whether a topical analgesic would reduce knee pain and improve the function of a group of 40- to 65-year-old people with chronic knee pain. The experimental design was a double-blind, randomized, placebo-controlled clinical trial. The dependent variables were knee pain, active range of motion, and isometric strength. Forty-six men and women volunteered, of whom 3 dropped out, leaving 23 in the treatment group and 20 in the placebo group. Knee pain was assessed with a visual analogue scale and the knee-pain scale for frequency and severity. Testing took place before treatment and after 21 and 35 days of treatment. The results indicated that although both groups experienced improved pain scores, there were no differences between groups over the treatment period for any of the dependent variables.