Biomechanical Analysis of Alignment in Standing Posture in Children with Cerebral Palsy

Abstract

The purpose of this study is to determine the quantitative relationship between the restriction of the ROM (range of motion) of joints and alignment in standing posture in children with cerebral palsy (CP). The measurement of alignment was carried out on three planes: horizontal, backward-inclined and forward-inclined planes. Alignment in CP children without a restricted ankle joint (NR-CP) was similar to that in normal subjects who can maintain an upright posture on any plane merely by adjusting the ankle joint alone. CP children with a restricted ankle joint (R-CP) demonstrated a severe crouching posture characterized by a forwardly inclined trunk, backwardly inclined thigh and forwardly inclined leg. This pathological posture may result not only from the contracture of the ankle joint but also from muscle shortening over the two joints. A biomechanical model of the restriction of the ROM was developed and used to simulate the alignment in a standing posture. The simulation results for normal and NR-CP subjects were consistent with the experimental measurements. However there was some difference between the simulation and the measurements for R-CP children, particularly for the forward-inclined plane. If the mathematical model used in this study accurately reflects the effect of the restriction of the ROM on the alignment, other factors such as impaired neuromuscular function might contribute to the difference. The present biomechanical approach is useful to develop effective measures for improving posture in CP children. © 1995, The Japan Society of Mechanical Engineers. All rights reserved.