A Preliminary Numerical Simulation Study of Developing Ankle Foot Orthosis to Support Sit-To-Stand Movement in Children with Cerebral Palsy

The purpose of this study is to identify an effective method of support for the standing-up motion of children with cerebral palsy (CP). Experiments revealed remarkable differences in the shank and upper-body motions of children with CP compared with normally developed (ND) children. Shank tilt angles of CP children were smaller and their upper-body tilt angles were larger than those of ND children. The large upper-body tilt compensates for the smaller shank tilt but will cause back pain and/or deformation of the hip joint as they grow. It is therefore imperative to find a method of support to help CP children realize more natural motions (similar to those of ND children) to prevent these problems. The standing-up motion of ND children was adopted as the goal. Experiments identified a similarity in the angular variation between ND children’s upper bodies and shanks; the standing-up motion of children with CP under that condition was then simulated using a two-dimensional four-link model of the human body. As a result of the numerical simulation, shank angles of CP children increased and their upper-body angles decreased from those measured during the experiments, which indicates that the proposed method of support is qualitatively effective at allowing CP children to realize a more natural standing-up motion. Keywords—Cerebral; palsy; Standing-up motion; Motion analysis; Numerical simulation; Rigid link model