THE RELIABILITY AND VALIDITY OF PAIN THRESHOLD MEASUREMENTS IN OSTEOARTHRITIS OF THE KNEE

The purpose of this study was to examine the reliability and validity of measuring pain threshold (PT) of persons with osteoarthritis (OA) o f the knee. The PTs of women with and without OA of the knee were meas ured on 3 occasions at 6 sites at the knee with a pressure dolorimeter . Subjects with OA also recorded their pain on a visual analogue scale (VAS) and on the McGill Pain Questionnaire (MPQ). The reliability coe fficients for repeated measures of PT varied from 0.61 to 0.91 in the OA group and from 0.71 to 0.90 in the control group. PT was lower in t he OA group at all sites. Only the control group demonstrated signific ant differences between sites. The correlations between PT and measure s of pain intensity were poor. It is concluded that the measurement of PT at the knee distinguishes OA from healthy controls, and that it ha s moderate reliability. However, it cannot substitute for a measure of pain intensity.