Imaging Modalities in the Outcome Assessment of Knee Osteoarthritis

Knee radiography is the current "gold standard" for assessing the severity of knee osteoarthritis (OA) in clinical and research settings. Nevertheless, radiographic evaluation of OA is an insensitive and unreliable measure for quantifying disease severity and change over relatively short periods of time. The failure of knee radiographs to provide a sensitive outcome measure may be one factor that has contributed to the limited progress that has been achieved in developing effective treatments to slow or stop the progression of knee OA. Emerging evidence suggests that measurement of articular cartilage volume using magnetic resonance imaging (MRI) is valid, reproducible and sensitive to change in both normal subjects and those with OA. This review discusses the issues related to joint imaging using radiographs and MRI in the outcome assessment of knee OA.