Assessment of wrist malalignment in juvenile rheumatoid arthritis

An important feature of wrist deformity in juvenile rheumatoid arthritis (JRA) is displacement of the carpus from its normal position relative to the forearm, i.e. malalignment. The aim of this study was to analyse and clarify some of the issues regarding the assessment of malalignment in the frontal plane in children with JRA. It is reasoned that the assessment of malalignment of the wrist should include measurements representing both modes of displacement with planar motion: rotation and translation. Regarding rotation, what is considered to be the "normal" position of the wrist and thus which measurement is used to assess rotation, was found to have profound implications for the conclusions to be drawn from that assessment. Furthermore, serious attention should be paid to the protocol for radiographic positioning. To assess translation of the carpus in JRA, the use of measurements based on an approximate to the wrist centre of rotation was explored. We found that the location of the approximate changes slightly with changes in wrist position, however, these changes were statistically significant. Therefore, this approximate is probably not useful in children with JRA. As treatment and the understanding of the pathophysiology of malalignment rely on the assessment of malalignment, a valid assessment is crucial. This study analysed and clarified some of the pitfalls, which will contribute to decision-making regarding treatment, and provides a basis for further research to enhance the valid assessment of malalignment.