Imaging and osteoarthritis: what is the predictive value?

Recent protocols for standardized knee radiography, which attempts to image the knee with reproducible, parallel alignment of the medial tibial plateau and radiograph beam, possess many theoretic advantages. As a group, they permit measurement of tibiofemoral joint space width with remarkable precision--the sine qua non of sensitive detection of change. However, only limited longitudinal data are available in peer-reviewed publications to permit a direct evaluation of the suitability of these protocols for use in multicenter clinical trials and studies of biomarkers of osteoarthritis (OA) progression. Longitudinal data from several National Institutes of Health-supported studies of OA progression, as reflected in radiographs acquired with high levels of standardization for radioanatomic positioning of the knee, should be available in the next several years. Alternatively, data from the placebo groups of several industry-supported phase III trials of purported disease-modifying OA drugs, which were terminated prematurely because of adverse events or lack of efficacy, may be made available for rapid analysis regarding the performance of current standardization protocols with respect to their sensitivity to disease progression.