Derivation of a Geometrical Shape of the Upper Extremity of Children

Preliminary tests have shown that the mathematical model of HATZE does not seem to be applicable for young children. Although even in young children the whole body mass calculated by using this model is predominantly in agreement with the actual measured weight, the masses of individual body segments are under- or overestimated. Because the model of HATZE is generated especially for adults and older children the question came up whether there is a difference between the segment shapes.

200 children aged 2 to 10 years were included in the study. A total of 13 measurements were taken. Based on these measurements a simplified geometrical shape of the upper and lower arm as well as the hand was assumed. These forms were compared with the shapes that are the fundament of the mathematical model of HATZE and the differences and possible reasons therefore were discussed.

Due to the anthropometrics a right circular cone was defined for the upper and the lower arm. The hand was assumed to be a cuboid with the base of an isosceles trapezium. The differences between these shapes and those defined by HATZE can possibly be explained by the used samples and the general growth pattern of children. These anthropometric measurements disclosed that the geometrical shapes partly differ for young children.

Using segment shapes derived from individual anthropometric measurements, the results of this study will serve the development and improvement of child models for the simulation of impact kinematics and related fields.