Age- and Sex-Specific Thorax Finite Element Model Development and Simulation

Abstract

Objective:The shape, size, bone density, and cortical thickness of the thoracic skeleton vary significantly with age and sex, which can affect the injury tolerance, especially in at-risk populations such as the elderly. Computational modeling has emerged as a powerful and versatile tool to assess injury risk. However, current computational models only represent certain ages and sexes in the population. The purpose of this study was to morph an existing finite element (FE) model of the thorax to depict thorax morphology for males and females of ages 30 and 70 years old (YO) and to investigate the effect on injury risk.Methods: Age-and sex-specific FE models were developed using thin-plate spline interpolation. In order to execute the thin-plate spline interpolation, homologous landmarks on the reference, target, and FE model are required. An image segmentation and registration algorithm was used to collect homologous rib and sternum landmark data from males and females aged 0-100 years. The Generalized Procrustes Analysis was applied to the homologous landmark data to quantify age-and sex-specific isolated shape changes in the thorax. The Global Human Body Models Consortium (GHBMC) 50th percentile male occupant model was morphed to create age-and sex-specific thoracic shape change models (scaled to a 50th percentile male size). To evaluate the thoracic response, 2 loading cases (frontal hub impact and lateral impact) were simulated to assess the importance of geometric and material property changes with age and sex.Results: Due to the geometric and material property changes with age and sex, there were observed differences in the response of the thorax in both the frontal and lateral impacts. Material property changes alone had little to no effect on the maximum thoracic force or the maximum percent compression. With age, the thorax becomes stiffer due to superior rotation of the ribs, which can result in increased bone strain that can increase the risk of fracture. For the 70-YO models, the simulations predicted a higher number of rib fractures in comparison to the 30-YO models. The male models experienced more superior rotation of the ribs in comparison to the female models, which resulted in a higher number of rib fractures for the males.Conclusion: In this study, age-and sex-specific thoracic models were developed and the biomechanical response was studied using frontal and lateral impact simulations. The development of these age-and sex-specific FE models of the thorax will lead to an improved understanding of the complex relationship between thoracic geometry, age, sex, and injury risk.

Regional maps of rib cortical bone thickness and cross‐sectional geometry

“…Despite the current knowledge that precise rib cross-geometry is crucial for predicting rib fracture properties, the incorporation of such geometry at the level of detail necessary to reflect true human variation has not been fully realized in current HBMs. When rib modifications are made to HBMs to simulate population-based differences, a greater emphasis is generally placed on altering material properties and gross thoracic geometry than on cross-sectional rib geometry to achieve the desired structural results (Ito et al 2009;Schoell et al 2015).…”

Advances in Computational Human Phantoms and Their Applications in Biomedical Engineering—A Topical Review

“…The Global Human Body Models Consortium (GHBMC) is an international consortium of seven different partners, most of whom are automobile manufacturers [102]. The consortium is working on the development of both male and female CHPs of different heights 4 in both standing and sitting positions [103] [104] [105]. The Total Human Model for Safety (THUMS) is a family of models developed by Toyota that include a 5 th percentile adult female, 50 th and 95 th percentile adult males, and 3, 6, and 10 year-old children [106] [107].…”

On dynamic behavior of bone: Experimental and numerical study of porcine ribs subjected to impact loads in dynamic three-point bending tests

“…The advances in computational ability and their advantages over expensive experimental procedures have led to the development of FE human body models such as Isolated thorax model (Schoell et al, 2015), the H-Model (Haug et al, 2004), the RADIOSS model (Arnoux et al, 2003), the THUMS model (Maeno and Hasegawa, 2001) and the HUMOS model (Robin, 2001). These FE human models have been used as a promising tool to overcome the limitations of experimental methods in the study of thoracic injuries.…”