A practical exercise in reading RA radiographs by the larsen and sharp methods.

A plenary radiograph reading session was conducted prior to the rheumatoid arthritis imaging group sessions to familiarize participants with radiograph scoring methods and their problems, and to introduce the concept of measurement error. After brief reviews on how to score radiographs using the Larsen and Sharp method, photographic slides of metacarpophalangeal joints of 2 patients were shown. Participants were asked to register their absolute scores on paper, and their progression scores on an interactive voting keypad, allowing immediate visualization of the results. The objectives of the session were clearly met, as evidenced by lively discussions in the groups. Participant mean scores agreed well with the expert scores. Sharp scores showed wider scatter between participants than Larsen scores. This was only partially explained by the greater score range inherent in the method. In addition, participants needed more time to score according to Sharp than Larsen. Participants were sensitized to the challenges of radiographic measurement of damage.