Abstract:
"Material Properties Of The Infant Skull And Application To Numerical Analysis Of Pediatric Head Injury"
The impact response of the infant head depends not only on its unique geometry, but also on the age-dependent mechanical properties of the skull and sutures. In this biomechanical study, human tissue samples containing cranial bone and sutures were taken from fresh surgical specimens and prepared as miniature specimens for mechanical testing in bending and tension to characterize their age-dependent material properties. The experimentally-determined constitutive behavior for infant skull and suture tissue was then implemented in three-dimensional finite element models of the pediatric head to examine the sensitivity of skull and brain strains to variations in the impact direction. These head impact simulations demonstrated the directional dependence of skull fracture and traumatic brain injury risk, highlighting the critical role of biomechanics in understanding pediatric head injury. While adult head injury has been extensively studied, quantitative assessment of injury mechanisms unique to the pediatric population is a more recent focus, recognizing the marked differences in geometry, structure, and material properties of the pediatric skull compared to adults. The neonatal skull, with its thin pliable bone plates and compliant sutures, is capable of substantial deformation during both childbirth and traumatic impact loading, and its mechanical properties change significantly with age as bone differentiates and sutures interdigitate. The application of numerical modeling techniques to study pediatric head injury has been limited by the availability of material property data and the complexity of the developing pediatric braincase. This research contributes by developing a finite element model of the three-month-old infant head, incorporating experimentally-derived elasto-plastic material properties for cranial bone and sutures, and utilizing these to simulate lateral and posterior impacts to investigate injury risk. The study found that human cranial bone is extremely compliant in early life, with its elastic modulus increasing dramatically with age, and that the 1000 N impact load resulted in plastic deformations of the skull bones and diffuse strain distribution throughout the brain. This work is a crucial step towards developing age-dependent finite element models for investigating injury thresholds in the pediatric population, emphasizing the importance of experimentally measured material properties in these biomechanical models.
