Characteristics of the joint position sense in children with developmental dyslexia.

[Purpose] Developmental dyslexia is a disorder in which reading and writing of characters is difficult. The present study investigated age-dependent joint position sense of the forearm and wrist and whether children with developmental dyslexia have less joint position sense than typically developing children. [Participants and Methods] The participants were comprised of 84 typically developing elementary school students, 12 university students, and 2 children with developmental dyslexia. Joint position sense was evaluated using the reproduction method based on four tasks. The participants were divided into three age groups. The children with developmental dyslexia were compared with the typically developing children in the same age group. [Results] Significant negative correlations were found between the reproduction error of the typically developing children and that of the university students in most tasks. The children with developmental dyslexia showed increased reproduction error relative to the reproduction error of the typically developing children in the same age group in 4 of the 8 tasks. [Conclusion] The accuracy of the joint position sense improved with development. However, the joint position sense of the children with developmental dyslexia was lower than that of the typically developing children in the same age group. The difficulty in writing experienced by children with developmental dyslexia may be related to joint position sensing impairment due to impaired joint position sense.