Development and construct validity of a knee pain questionnaire.

A knee pain questionnaire, consisting of 15 dichotomous items, was submitted to an item analysis, based on the probabilistic model of Rasch. Five items had to be discarded but the remaining 10 constituted a homogeneous set, fit to be used as a scale. In particular, this meant that the total number of positive responses to the questionnaire could be used as a simple measure of the patients' knee pain. Further studies must be performed in order to analyze the reliability and empirical validity of the scale.