Pathokinesiology of wrist deformity in juvenile chronic arthritis: State of the art

To treat wrist deformity in children with juvenile chronic arthritis (JCA), the underlying pathokinesiology needs to be understood. Such understanding, in common with rheumatoid arthritis (RA), is based mainly on knowledge of the pathogenesis and roentgenographic assessment of the abnormal displacement of the (meta)carpus. Loss of ligamentous constraint in combination with the compressive forces of the muscles acting across the wrist and the inclination angle of the radius are understood to predispose malalignment. However, the occurrence of different patterns of malalignment cannot be explained by current pathokinesiological concepts. Incorporating the dysfunctionality of the forearm muscles, which accompanies synovitis, into the pathokinesiological concept may contribute to the understanding of the variation in patterns of wrist malalignment in particular and the pathokinesiology of wrist deformity in general. For effective treatment, it must be clear why and how different muscles are affected. Furthermore, consideration must be given to the validity of methods for the assessment of malalignment in RA and the development of such a method for JCA.