Quantitative radiography in osteoarthritis: Plain radiographs

Summary Radiological assessment of joint space width on plain radiographs is the most frequently used primary outcome criterion in clinical trials of disease modifying drugs. Changes in measurement over time are slow. Therefore, in order to improve the capacity of measurement to detect changes, the sources of variability (i.e. radigraphic procedure, joint positioning, process of measurements, etc.) must be limited. Precise guidelines concerning radiographic procedure, joint positioning and methods of reading are requred to achieve this goal.