Effects of Body Weight, Height, and Rib Cage Area Moment of Inertia on Blunt Chest Impact Response

Abstract

Objective: The purpose of this study was to determine the effects of body weight, height, and rib cage area moment of inertia on human chest impact responses in frontal pendulum impacts.

Methods: A series of parametric studies was conducted with 11 cases of finite element (FE) analysis using a commercially available three-dimensional (3-D) FE model of the whole human body, Total HUman Model for Safety (THUMS). Selected parameters in this study were body weight, height, and area moment of inertia of the rib cage and of the ribs alone. Three body sizes assumed were those of a large male (AM95), a mid-sized male (AM50), and a small female (AF05). The initial impact response, maximum chest force, maximum deflection, maximum compression ratio, and the number of rib fractures and fractured ribs were examined for statistical analysis.

Results: Body weight and height of the human body do not show any correlation with any injury variable considered in this study. However, area moment of inertia of the rib cage correlated (r = −0.86 and p = 0.001) with maximum chest compression ratio, which is the best predictor of the number of rib fractures.

Conclusion: The area moment of inertia of the rib cage or ribs alone would affect the response and injury variables in frontal pendulum impacts.

Keywords:

• Biomechanics
• Thorax
• Finite element method
• Frontal impacts
• Area moment of inertia

Notes

^a Values in parentheses are weight (unit: kg), height (unit: m), and cortical bone thickness (unit: mm) for sternum and ribs.