The Effects of Seat Surface Inclination on Forward Reaching in Children with Spastic Cerebral Palsy

Purpose: Impaired reaching movement is commonly observed in children with cerebral palsy. The purpose of this study was to determine whether the inclination of seat surface can influence the reaching movement in children with spastic diplegic cerebral palsy (CP). Methods: The subjects were 31 children, 16 children with spastic bilateral CP and 15 typically developing (TD) children. The children performed static sitting and forward reaching under three conditions: a horizontal seat surface (Horizontal $0^{\circ}$), a seat surface inclined anterior 15 degrees (Ant $15^{\circ}$), and a seat surface inclined posterior 15 degrees (Post $15^{\circ}$). A 3-axis accelerometer ('ZSTAR3') was used for analysis of the reaching movement. A 3-axis accelerometer was attached on the manubrium of the sternum, lateral epicondyle of the humerus, and styloid process of the ulna. We measured the reaction time, movement time, and data amount during reaching the 8 cm target with an index finger on the three inclined seat surfaces. Results: Reaction time and movement time for CPs showed significant delay; comparing the TD's and CP's amount was significantly greater than the TD's during reaching task (p<0.05). In particular, CP's reaction time and movement time on a seat surface inclined Ant $15^{\circ}$ was significantly more delayed compared with the other seat surfaces (p<0.05). Conclusion: Our results suggest that seat-inclination intervention may provide an ergonomic approach for children with spastic cerebral palsy.