Biomechanics of Abusive Head Trauma

QC 2025-11-12

Abstract

Abusive head trauma (AHT) is a controversial and scientifically disputed medical diagnosis, particularly in infants. Existing symptom-based diagnostic approaches lack rigorous scientific validation, and misdiagnosis can not only cause devastating harm to affected families but also undermine public trust in both medical and judicial systems.     Finite element (FE) method offers a promising approach to investigate the injury mechanisms of infants under various suspected abuse scenarios. By providing anatomically accurate geometries and realistic material properties, it enables simulations that replicate realistic infant responses and the associated injury mechanisms. 

The anatomical and biomechanical characteristics of infants differ substantially from those of adults, including a larger head-to-body mass ratio than adults, open sutures and fontanelles, less ossified cranial bones, and more vulnerable cervical spine. This thesis focuses on these distinct features, explores efficient methods for generating both subject-specific and statistically based infant FE models, and further applies biomechanical approaches to evaluate infant head and neck injuries under different scenarios. Specifically, the work comprises five studies. The first study develops a quantitative framework for measuring the morphological parameters of infant cranial sutures and fontanelles. The second study applies this framework to computed tomography (CT) images of infants in the first year of life to characterize growth charts and establish developmental trajectories for sutures and fontanelles.    The third study presents and validates a material model for the infant cranial vault and proposes a method to reconstruct vault fracture patterns for subject-specific infant  FE head models. The fourth study develops an automated algorithm to modify infant FE head models with varying suture morphologies and investigates the biomechanical influence of suture and fontanelle morphology on the infant head. The last study consists of two parts: (1) the development of a full-body FE model of a two-month-old infant with a validated cervical spine, and (2) transient dynamic analyses to investigate head and neck responses under multi-cycle vigorous shaking loads associated with AHT scenarios.

Collectively, the five studies establish an integrated biomechanical framework for assessing AHT in infants, progressing from quantitative anatomical data and medical imaging to subject-specific FE modeling and dynamic simulation applications. Studies I–III quantify skull, suture, and fontanelle morphology and growth, creating the anatomical and material foundations for subject-specific modeling.  Studies IV and V apply these material models and anatomical data to FE simulations that explore how morphological variability influence head biomechanics and how infant head and neck respond under inflicted shaking. Together, this thesis  demonstrates the potential of biomechanics, particularly the FE method,  and provides a comprehensive pipeline for  subject-specific assessment of infant head and neck injuries, supporting forensic analysis of AHT and advancing understanding of the underlying biomechanical mechanisms.

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