Abstract
Computational models of infant head impact are limited by the paucity of infant cranial bone material property data, particularly with regards to the anisotropic relationships created by the trabecular fibers in infant bone. We previously reported high-rate material property data for human infant cranial bone tested perpendicular to trabeculae fiber orientation. In this study we measure the anisotropic properties of human infant cranial bone by analyzing bending modulus parallel to the trabeculae fibers. We tested human bone specimens from 9 donors ranging in age from 32 weeks gestational age to 10 months of age at strain rates 12.3-30.1 s^(-1). Bending modulus significantly increased with donor age (p=0.008), and was 13.4 times greater along the fiber direction compared to perpendicular to the fibers. Ultimate stress was greater by 5.1 times when tested parallel to the compared to perpendicular (p=0.067). Parietal bone had a higher modulus and ultimate stress compared to occipital bone, but this trend was not significant, as previously shown perpendicular to fiber orientation. Combined, these data suggest the pediatric skull is highly age-dependent, anisotropic, and regionally dependent. The incorporation of these characteristics in finite element models of infant head impact will be necessary to advance pediatric head injury research, and further our understanding of the mechanisms of head injury in children.
High-Rate Anisotropic Properties in Human Infant Parietal and Occipital Bone
