Parametric study of head response by finite element modeling
TL;DR: The results revealed that the load spatial distribution strongly influenced skull and, consequently, the load required to initiate skull fracture, and the other parameters produced small effects on the models' responses.
About: This article is published in Journal of Biomechanics.The article was published on 1977-01-01. It has received 123 citations till now. The article focuses on the topics: Spherical shell & Human head.
Citations
More filters
TL;DR: In this paper, the authors used a 0.2-T open-configuration, magnetic resonance imaging scanner, located in an operating theater, for pre-and intra-operative imaging.
Abstract: Objective Modern neuronavigation systems lack spatial accuracy during ongoing surgical procedures because of increasing brain deformation, known as brain shift. Intraoperative magnetic resonance imaging was used for quantitative analysis and visualization of this phenomenon. Methods For a total of 64 patients, we used a 0.2-T, open-configuration, magnetic resonance imaging scanner, located in an operating theater, for pre- and intraoperative imaging. The three-dimensional imaging data were aligned using rigid registration methods. The maximal displacements of the brain surface, deep tumor margin, and midline structures were measured. Brain shift was observed in two-dimensional image planes using split-screen or overlay techniques, and three-dimensional, color-coded, deformable surface-based data were computed. In selected cases, intraoperative images were transferred to the neuronavigation system to compensate for the effects of brain shift. Results The results demonstrated that there was great variability in brain shift, ranging up to 24 mm for cortical displacement and exceeding 3 mm for the deep tumor margin in 66% of all cases. Brain shift was influenced by tissue characteristics, intraoperative patient positioning, opening of the ventricular system, craniotomy size, and resected volume. Intraoperative neuronavigation updating (n = 14) compensated for brain shift, resulting in reliable navigation with high accuracy. Conclusion Without brain shift compensation, neuronavigation systems cannot be trusted at critical steps of the surgical procedure, e.g., identification of the deep tumor margin. Intraoperative imaging allows not only evaluation of and compensation for brain shift but also assessment of the quality of mathematical models that attempt to describe and compensate for brain shift.
510 citations
TL;DR: Results of the simulation suggest that skull deformation and internal partitions may be responsible for the directional sensitivity of the head in terms of intracranial pressure and shear stress response, and that the head would tend to have a decreased tolerance to shear deformation in lateral impact.
Abstract: This study was conducted to investigate differences in brain response due to frontal and lateral impacts based on a partially validated three-dimensional finite element model with all essential anatomical features of a human head. Identical impact and boundary conditions were used for both the frontal and lateral impact simulations. Intracranial pressure and localized shear stress distributions predicted from these impacts were analyzed. The model predicted higher positive pressures accompanied by a relatively large localized skull deformation at the impact site from a lateral impact when compared to a frontal impact. Lateral impact also induced higher localized shear stress in the core regions of the brain. Preliminary results of the simulation suggest that skull deformation and internal partitions may be responsible for the directional sensitivity of the head in terms of intracranial pressure and shear stress response. In previous experimental studies using subhuman primates, it was found that a lateral impact was more injurious than a frontal impact. In this study, shear stress in the brain predicted by the model was much higher in a lateral impact in comparison with a frontal impact of the same severity. If shear deformation is considered as an injury indicator for diffuse brain injuries, a higher shear stress due to a lateral impact indicate that the head would tend to have a decreased tolerance to shear deformation in lateral impact. More research is needed to further quantify the effect of the skull deformation and dural partitions on brain injury due to impacts from a variety of directions and at different locations.
307 citations
TL;DR: The pattern and magnitude of stresses in the periodontium from a given magnitude of force were markedly different, depending on the center of rotation of the tooth.
269 citations
TL;DR: The authors report on the initial development of a finite element model of brain tissue adapted from consolidation theory that could be used in conjunction with a limited amount of concurrently obtained operative data to estimate subsurface tissue motion.
Abstract: Recent advances in the field of sterotactic neurosurgery have made it possible to coregister preoperative computed tomography (CT) and magnetic resonance (MR) images with instrument locations in the operating field. However, accounting for intraoperative movement of brain tissue remains a challenging problem. While intraoperative CT and MR scanners record concurrent tissue motion, there is motivation to develop methodologies which would be significantly lower in cost and more widely available. The approach the authors present is a computational model of brain tissue deformation that could be used in conjunction with a limited amount of concurrently obtained operative data to estimate subsurface tissue motion. Specifically, the authors report on the initial development of a finite element model of brain tissue adapted from consolidation theory. Validations of the computational mathematics in two and three dimensions are shown with errors of 1%-2% for the discretizations used. Experience with the computational strategy for estimating surgically induced brain tissue motion in vivo is also presented. While the predicted tissue displacements differ from measured values by about 15%, they suggest that exploiting a physics-based computational framework for updating preoperative imaging databases during the course of surgery has considerable merit. However, additional model and computational developments are needed before this approach can become a clinical reality.
233 citations
TL;DR: The transmission properties of bone conducted sound in human head are presented, measured as the three-dimensional vibration at the cochlear promontory in six intact cadaver heads, found to be nondispersive at frequencies above 2 kHz whereas it altered with frequency at the cranial vault.
Abstract: In the past, only a few investigations have measured vibration at the cochlea with bone conduction stimulation: dry skulls were used in those investigations In this paper, the transmission properties of bone conducted sound in human head are presented, measured as the three-dimensional vibration at the cochlear promontory in six intact cadaver heads The stimulation was provided at 27 positions on the skull surface and two close to the cochlea; mechanical point impedance was measured at all positions Cochlear promontory vibration levels in the three perpendicular directions were normally within 5 dB With the stimulation applied on the ipsilateral side, the response decreased, and the accumulated phase increased, with distance between the cochlea and the excitation position No significant changes were obtained when the excitations were on the contralateral side In terms of vibration level, the best stimulation position is on the mastoid close to the cochlea; the worst is at the midline of the skull The transcranial transmission was close to 0 dB for frequencies up to 700 Hz; above it decreased at 12 dB/decade Wave transmission at the skull-base was found to be nondispersive at frequencies above 2 kHz whereas it altered with frequency at the cranial vault (c) 2005 Acoustical Society of America
210 citations
References
More filters
TL;DR: Method is capable of application to structures of any degree of complication, with any relationship between force and displacement, from linear elastic behavior through various degrees of inelastic behavior or plastic response, up to failure.
Abstract: A general procedure for the solution of problems in structural dynamics is described herein. The method is capable of application to structures of any degree of complication, with any relationship ...
4,436 citations
TL;DR: In this paper, the method is capable of application to structures of any degree of complication, with any relationship between force and displacement, from linear elastic behavior through various degrees of inelastic behavior or plastic response, up to failure; any type of dynamic loading, due to shock or impact, vibration, earthquake, or nuclear blast can be considered.
Abstract: Method is capable of application to structures of any degree of complication, with any relationship between force and displacement, from linear elastic behavior through various degrees of inelastic behavior or plastic response, up to failure; any type of dynamic loading, due to shock or impact, vibration, earthquake, or nuclear blast can be considered; use of high-speed digital computers.
4,176 citations
TL;DR: Solutions for the indentation of the layer by the plane end of a rigid circular cylinder and by a rigid sphere are suggested as useful for the determination of the elastic shear modulus of intact cartilage.
899 citations
TL;DR: The results show that there is no detectable variation in the properties for all specimen orientations tangent to the surface of the skull, and these data provide a basis for selecting candidate materials for a physical head model.
242 citations
TL;DR: The layered beam theory used in this study was found to provide a valid relationship between the constituent material properties and structural geometry of layered cranial bone and its flexural response.
127 citations