Abstract The geometry and mechanical properties of infant skull bones differ significantly from those of adults. Over the past decades, debates surrounding whether fractures in infants come from deliberate abuse or accidents have generated significant impacts in both legal and societal contexts. However, the etiology of infant skull fractures remains unclear, which motivates this study with two main components of work. Firstly, we present and implement a progressive unidirectional fabric composite damage model for infant cranial vaults to represent ductile and anisotropic properties—two typical mechanical characteristics of infant skulls. Secondly, we hypothesize that these intrinsic material properties cause injuries perpendicular to the fiber direction to dominate infant skull fractures, resulting in fracture lines that align with the direction of mineralization in the infant skull. The material model and the finite element (FE) model were verified hierarchically, and this hypothesis was verified by reconstructing two legal cases with known fall heights and implementing the above damage model into CT-based subject-specific infant FE head models. We discovered that the infant skull is more susceptible to injuries within planes perpendicular to the mineralization direction because of the anisotropic mechanical property caused by the direction of mineralization, leading to infant skull fractures aligning with the mineralization direction. Our findings corroborated the several previously reported observations of fractures on cranial vaults, demonstrating that these fractures were closely associated with sutures and oriented along the mineralization direction, and revealed the underlying mechanisms of infant skull fracture pattern. The modeling methods and results of this study will serve as an anchor point for more rigorous investigations of infant skull fractures, ultimately aiming to provide convincing biomechanical evidence to aid forensic diagnoses of abusive head trauma.

Siyuan Chen

Svein Kleiven

Xiaogai Li

Biomechanics and Modeling in Mechanobiology

力学在分子、细胞、组织、器官和有机体水平上调节生物过程。该杂志的一个目标是促进基础和应用研究，整合生物力学和机械生物学相关领域不断扩大的知识库。方法可以是实验的、理论的或计算的；它们可以解决纳米、微观或宏观层面的现象。特别感兴趣的是以下研究：(1) 量化细胞和基质在健康、疾病或损伤中发挥作用的机械环境，(2) 识别和量化机械敏感反应及其机制，(3) 详细说明力学和生物学之间的相互关系生长、重塑、适应和修复等过程，以及 (4) 报告推进治疗和诊断程序的发现。特别鼓励基于固体力学、流体力学或热力学及其相互作用的分析和计算模型；还鼓励报告扩展测量能力的新实验方法和促进分析的新数学方法。

Mechanics regulates biological processes at the molecular, cellular, tissue, organ, and organism levels. The aim of this journal is to promote both fundamental and applied research, integrating the expanding knowledge base in the fields of biomechanics and mechanobiology. The methods can be experimental, theoretical, or computational, addressing phenomena at the nano, micro, or macro levels. The journal is particularly interested in the following research areas: (1) quantifying the mechanical environment of cells and the extracellular matrix in health, disease, or injury; (2) identifying and quantifying mechanosensitive responses and their mechanisms; (3) detailing the interplay between mechanics and biology in processes such as growth, remodeling, adaptation, and repair; and (4) reporting discoveries that advance therapeutic and diagnostic procedures. Analyses and computational models based on solid mechanics, fluid mechanics, or thermodynamics and their interactions are especially encouraged, as are reports of new experimental methods that enhance measurement capabilities and new mathematical approaches that facilitate analysis.

力学在分子、细胞、组织、器官和有机体水平上调节生物过程。该杂志旨在促进基础和应用研究，整合生物力学和机械生物学相关领域不断扩大的知识库。研究方法可以是实验的、理论的或计算的，涵盖纳米、微观或宏观层面的现象。特别关注以下研究方向：(1) 量化细胞和基质在健康、疾病或损伤中的机械环境；(2) 识别和量化机械敏感反应及其机制；(3) 详细阐述力学与生物学之间的相互关系，包括生长、重塑、适应和修复等过程；(4) 报告推动治疗和诊断程序的发现。特别鼓励基于固体力学、流体力学或热力学及其相互作用的分析和计算模型，同时也鼓励报告扩展测量能力的新实验方法和促进分析的新数学方法。

Category	Quartile
医学	3
医学, 生物物理	2
医学, 工程生物医学	3

Infant skull fractures align with the direction of bone mineralization

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Journal Info

Category	Quartile
ENGINEERING, BIOMEDICAL	3