An improved and detailed 3D FE model of human cervical spine model was created using digitized ge... more An improved and detailed 3D FE model of human cervical spine model was created using digitized geometric measurement tool. The vertebral bodies of the model were fused at three locations. The unfused and the fused models were physiologically loaded and the changes in stresses in intervertebral discs were compared. A moment of 1.5 Nm was used in combination with a 50 N compressive preload. The results showed that the lower cervical spine fusion induces the most stress changes in the neighboring discs.
The authors gratefully acknowledge Bryan A. Cheeseman and Robert B. Dooley of ARL-WMD for their s... more The authors gratefully acknowledge Bryan A. Cheeseman and Robert B. Dooley of ARL-WMD for their support and guidance in ballistic impact behaviors. Special thanks are given to Charles Howland of Warwick Mills, New Ipswich, NH, for sharing his technical expertise in yarn materials, ballistic fabric constructions, and textile manufacturing. The technical reviewer was Andrew J. Hull (Code 8212).
During an emergency ejection from aircraft, pilots are subjected to a high acceleration that coul... more During an emergency ejection from aircraft, pilots are subjected to a high acceleration that could cause injuries. To determine the forces and torques at the head, neck and upper-torso joints, an ATB model was developed. The model was validated with test results for G-y accelerations of human subjects. The sled test results of human subjects were used and the loads and torques were determined. The results indicated that the maximum forces and torques increas with the increase in the amplitude and duration of the input acceleration; however, the maximum compressive force at the head pin has a minimum value of 150 lb at 5.5 G.
International Journal of Experimental and Computational Biomechanics, 2018
The SEM study revealed that the trabecular architectures in the subarachnoid space (SAS) are in t... more The SEM study revealed that the trabecular architectures in the subarachnoid space (SAS) are in the form of tree-shaped rods, pillars, plates or a complex network. In this paper, the effects of pillar and tree-shaped trabeculae on transferring an impact load and a pressure wave to the brain have been investigated. Indeed, two sets of local 3D FE models, including the brain and the SAS with rod and tree-shaped trabeculae were created. The models were subjected to pressure histories from the blunt impact and the shockwave scenarios. The results indicated that the thickness, shape and architecture of the trabeculae would not affect the severity of loads transferring to the brain from shock waves. In cases of blunt impact scenario, the presence of trabeculae would reduce the load transferring to the brain and also the upright tree shaped trabeculae perform stronger in protecting the brain, comparing to the inverted ones.
A detailed and validated 3D FE model of human cervical spine (Sadegh et al. 2000) was altered to ... more A detailed and validated 3D FE model of human cervical spine (Sadegh et al. 2000) was altered to simulate partial fusion. Five single level partially fused new models, one at each disc level, were used to study the change in stresses in adjacent levels. Two cases of partial fusion, 80% and 60% were considered. The fused models were loaded with a 50 N compressive pre-load and with a 1.5 Nm moment in flexion, extension, lateral bending and axial rotation. The previously obtained results of the unfused model (Tchako et al. 2002) and of the fused models were used to study the change in stresses in adjacent levels. The results indicate that, in general, there are stress changes as high as 94%, depending on the loading mode and location, in adjacent discs after discectomy and fusion. However, the difference between the stress change of 80% and 60% of partial fusion is insignificant.
Volume 3: Biomedical and Biotechnology Engineering, 2017
Traumatic brain injury (TBI) is an intracranial injury caused by impacts or angular accelerations... more Traumatic brain injury (TBI) is an intracranial injury caused by impacts or angular accelerations of the head such as a violent blow, a bump, a projectile, or even a blast. TBI is a major problem that accounts for over 1.4 million emergency room visits in US. Thus, it is important to understand and predict the occurrence of TBI. Previous studies have shown that the interaction between the subarachnoid space (SAS) trabeculae and the cerebrospinal fluid (CSF) plays an important role in damping the effect of impacts and reducing the brain injuries. However, the influence of sulci parameters and sulci trabeculae in impact induced TBI is still unexplored. A few studies have shown that inclusion of sulci in brain models alters the brain injuries conclusions, even though those models do not take into account the trabecular tissue present in the sulci. In this study, to obtain a perspective of the morphology and architecture of the sulci trabeculae at the frontal lobe of the brain, Human ca...
Mild traumatic brain injury (mTBI) and concussion could occur in vehicular accidents, contact spo... more Mild traumatic brain injury (mTBI) and concussion could occur in vehicular accidents, contact sports, or other physical traumas when the head is subjected to high linear or angular acceleration. Understanding the physiology and dynamics of such events has attracted many researchers’ attention. Due to the hidden risks in such events, it is very important to understand the cause and effect of the relative motion between the brain and skull and the implications of normal and shear stresses in the meningeal region. Since the early 70’s to date wide variations of experimental, analytical, and numerical models has been developed to analyze multilayer spherical head impact model to quantify the dynamic response of the human head due to blunt impact and explain the process and likely cause of mild traumatic brain injuries. There are many high-fidelity finite element models and research studies of the various head models, but very limited analytical models to date for parametric studies. Ana...
Volume 3: Biomedical and Biotechnology Engineering, 2019
The brain is encased in the skull and suspended and supported by a series of three fibrous tissue... more The brain is encased in the skull and suspended and supported by a series of three fibrous tissue layers: Dura mater, Arachnoid and Pia matter, known as the Meninges. Arachnoid trabeculae are strands of collagen tissues located in a space between the arachnoid and the pia matter known as the subarachnoid space (SAS). The SAS trabeculae play an important role in damping and reducing the relative movement of the brain with respect to the skull. The SAS is filled with cerebrospinal fluid (CSF), which is a colorless fluid that surrounds all over the brain inside the subarachnoid spaces. This fluid stabilizes the shape and position of the brain during head movements. To address normal and pathological SAS functions, under conditions where an electrical stimulation is applied, this study proposes a novel fully-coupled electro-Fluid-Structure Interaction (eFSI) modeling approach to investigate the response of the system of SAS-CSF under the applied electric current, which is provided by th...
International Journal of Experimental and Computational Biomechanics, 2016
In this paper, the induced pressure in blood vessels of the brain due to a blast has been investi... more In this paper, the induced pressure in blood vessels of the brain due to a blast has been investigated. An idealised experiment was designed, consisting of a ballistic rectangular gel block with a built-in conduit filled with water, representing the brain with a blood vessel, was placed in front of a shock tube. The experimental setup was simulated by a local 3D FE model which was validated with the experimental data. Results demonstrated that the skull, brain and meningeal layers reduce the intensity of a primary blast wave by a factor of 86 until it reaches the brain vessels. Furthermore, it was concluded that the striking shock waves with BOP greater than 5 MPa would increase the blood pressure to the critical level of 57 kPa which could onset failure and cause hematoma.
Volume 2: Biomedical and Biotechnology Engineering, 2008
Blunt head impacts cause relative motion between the brain and skull. This increases the normal a... more Blunt head impacts cause relative motion between the brain and skull. This increases the normal and shear stresses in the (skull/brain) interface region, which leads to the rupture of cerebral blood vessels and in particular bridging veins. Mechanical properties of meningeal layers, in particular, subarachnoid space (SAS) trabeculae and the pia mater are not well established in the literature and could have a wide range depending on an individual. In our previous studies, knowing that SAS trabeculae and pia mater are collagen-based structures, these mechanical properties have been estimated using the properties of similar collagen based tissues. However, recent study Xin Jin et al. (2008), suggests that the mechanical properties of trabeculae and the pia matter are significantly less than a collagen-based tissue. Therefore, the goal of this study is to investigate the effect of the mechanical properties of these tissue on the stress and strain of the neighboring tissues when the hea...
Abstract—Aneurysms of the cerebral arteries have potential risk of rupture which leads to intracr... more Abstract—Aneurysms of the cerebral arteries have potential risk of rupture which leads to intracranial hemorrhage that could be fatal. Nearly 1 to 5 percent of population has cerebral aneurysm; however 50 to 80 percent of these cases never face rupture of cerebral arteries ...
Blunt head impact arising from vehicular collisions, sporting injuries, and falls leads to relati... more Blunt head impact arising from vehicular collisions, sporting injuries, and falls leads to relative motion between the brain and skull and an increase in contact and shear stresses in the meningeal region, and leading to traumatic brain injuries. While there have been many finite element studies of the brain/head models there are limited analytical models. The goal of the present paper is to mathematically model subarachnoid space (SAS) and the meningeal layers and to investigate the motion of the brain relative to the skull, and their damping characteristics, during blunt head impacts. Based on the experimental studies of Hardy et al [6] the elasticity of the springs and damping constants of the dashpots were determined. The nonlinear governing integro-differential equations were formed and solved. The results of the analytical method are validated by performing an explicit finite element analysis. Acceptable agreement between these two methods is observed. The elastic deformation ...
An improved and detailed 3D FE model of human cervical spine model was created using digitized ge... more An improved and detailed 3D FE model of human cervical spine model was created using digitized geometric measurement tool. The vertebral bodies of the model were fused at three locations. The unfused and the fused models were physiologically loaded and the changes in stresses in intervertebral discs were compared. A moment of 1.5 Nm was used in combination with a 50 N compressive preload. The results showed that the lower cervical spine fusion induces the most stress changes in the neighboring discs.
The authors gratefully acknowledge Bryan A. Cheeseman and Robert B. Dooley of ARL-WMD for their s... more The authors gratefully acknowledge Bryan A. Cheeseman and Robert B. Dooley of ARL-WMD for their support and guidance in ballistic impact behaviors. Special thanks are given to Charles Howland of Warwick Mills, New Ipswich, NH, for sharing his technical expertise in yarn materials, ballistic fabric constructions, and textile manufacturing. The technical reviewer was Andrew J. Hull (Code 8212).
During an emergency ejection from aircraft, pilots are subjected to a high acceleration that coul... more During an emergency ejection from aircraft, pilots are subjected to a high acceleration that could cause injuries. To determine the forces and torques at the head, neck and upper-torso joints, an ATB model was developed. The model was validated with test results for G-y accelerations of human subjects. The sled test results of human subjects were used and the loads and torques were determined. The results indicated that the maximum forces and torques increas with the increase in the amplitude and duration of the input acceleration; however, the maximum compressive force at the head pin has a minimum value of 150 lb at 5.5 G.
International Journal of Experimental and Computational Biomechanics, 2018
The SEM study revealed that the trabecular architectures in the subarachnoid space (SAS) are in t... more The SEM study revealed that the trabecular architectures in the subarachnoid space (SAS) are in the form of tree-shaped rods, pillars, plates or a complex network. In this paper, the effects of pillar and tree-shaped trabeculae on transferring an impact load and a pressure wave to the brain have been investigated. Indeed, two sets of local 3D FE models, including the brain and the SAS with rod and tree-shaped trabeculae were created. The models were subjected to pressure histories from the blunt impact and the shockwave scenarios. The results indicated that the thickness, shape and architecture of the trabeculae would not affect the severity of loads transferring to the brain from shock waves. In cases of blunt impact scenario, the presence of trabeculae would reduce the load transferring to the brain and also the upright tree shaped trabeculae perform stronger in protecting the brain, comparing to the inverted ones.
A detailed and validated 3D FE model of human cervical spine (Sadegh et al. 2000) was altered to ... more A detailed and validated 3D FE model of human cervical spine (Sadegh et al. 2000) was altered to simulate partial fusion. Five single level partially fused new models, one at each disc level, were used to study the change in stresses in adjacent levels. Two cases of partial fusion, 80% and 60% were considered. The fused models were loaded with a 50 N compressive pre-load and with a 1.5 Nm moment in flexion, extension, lateral bending and axial rotation. The previously obtained results of the unfused model (Tchako et al. 2002) and of the fused models were used to study the change in stresses in adjacent levels. The results indicate that, in general, there are stress changes as high as 94%, depending on the loading mode and location, in adjacent discs after discectomy and fusion. However, the difference between the stress change of 80% and 60% of partial fusion is insignificant.
Volume 3: Biomedical and Biotechnology Engineering, 2017
Traumatic brain injury (TBI) is an intracranial injury caused by impacts or angular accelerations... more Traumatic brain injury (TBI) is an intracranial injury caused by impacts or angular accelerations of the head such as a violent blow, a bump, a projectile, or even a blast. TBI is a major problem that accounts for over 1.4 million emergency room visits in US. Thus, it is important to understand and predict the occurrence of TBI. Previous studies have shown that the interaction between the subarachnoid space (SAS) trabeculae and the cerebrospinal fluid (CSF) plays an important role in damping the effect of impacts and reducing the brain injuries. However, the influence of sulci parameters and sulci trabeculae in impact induced TBI is still unexplored. A few studies have shown that inclusion of sulci in brain models alters the brain injuries conclusions, even though those models do not take into account the trabecular tissue present in the sulci. In this study, to obtain a perspective of the morphology and architecture of the sulci trabeculae at the frontal lobe of the brain, Human ca...
Mild traumatic brain injury (mTBI) and concussion could occur in vehicular accidents, contact spo... more Mild traumatic brain injury (mTBI) and concussion could occur in vehicular accidents, contact sports, or other physical traumas when the head is subjected to high linear or angular acceleration. Understanding the physiology and dynamics of such events has attracted many researchers’ attention. Due to the hidden risks in such events, it is very important to understand the cause and effect of the relative motion between the brain and skull and the implications of normal and shear stresses in the meningeal region. Since the early 70’s to date wide variations of experimental, analytical, and numerical models has been developed to analyze multilayer spherical head impact model to quantify the dynamic response of the human head due to blunt impact and explain the process and likely cause of mild traumatic brain injuries. There are many high-fidelity finite element models and research studies of the various head models, but very limited analytical models to date for parametric studies. Ana...
Volume 3: Biomedical and Biotechnology Engineering, 2019
The brain is encased in the skull and suspended and supported by a series of three fibrous tissue... more The brain is encased in the skull and suspended and supported by a series of three fibrous tissue layers: Dura mater, Arachnoid and Pia matter, known as the Meninges. Arachnoid trabeculae are strands of collagen tissues located in a space between the arachnoid and the pia matter known as the subarachnoid space (SAS). The SAS trabeculae play an important role in damping and reducing the relative movement of the brain with respect to the skull. The SAS is filled with cerebrospinal fluid (CSF), which is a colorless fluid that surrounds all over the brain inside the subarachnoid spaces. This fluid stabilizes the shape and position of the brain during head movements. To address normal and pathological SAS functions, under conditions where an electrical stimulation is applied, this study proposes a novel fully-coupled electro-Fluid-Structure Interaction (eFSI) modeling approach to investigate the response of the system of SAS-CSF under the applied electric current, which is provided by th...
International Journal of Experimental and Computational Biomechanics, 2016
In this paper, the induced pressure in blood vessels of the brain due to a blast has been investi... more In this paper, the induced pressure in blood vessels of the brain due to a blast has been investigated. An idealised experiment was designed, consisting of a ballistic rectangular gel block with a built-in conduit filled with water, representing the brain with a blood vessel, was placed in front of a shock tube. The experimental setup was simulated by a local 3D FE model which was validated with the experimental data. Results demonstrated that the skull, brain and meningeal layers reduce the intensity of a primary blast wave by a factor of 86 until it reaches the brain vessels. Furthermore, it was concluded that the striking shock waves with BOP greater than 5 MPa would increase the blood pressure to the critical level of 57 kPa which could onset failure and cause hematoma.
Volume 2: Biomedical and Biotechnology Engineering, 2008
Blunt head impacts cause relative motion between the brain and skull. This increases the normal a... more Blunt head impacts cause relative motion between the brain and skull. This increases the normal and shear stresses in the (skull/brain) interface region, which leads to the rupture of cerebral blood vessels and in particular bridging veins. Mechanical properties of meningeal layers, in particular, subarachnoid space (SAS) trabeculae and the pia mater are not well established in the literature and could have a wide range depending on an individual. In our previous studies, knowing that SAS trabeculae and pia mater are collagen-based structures, these mechanical properties have been estimated using the properties of similar collagen based tissues. However, recent study Xin Jin et al. (2008), suggests that the mechanical properties of trabeculae and the pia matter are significantly less than a collagen-based tissue. Therefore, the goal of this study is to investigate the effect of the mechanical properties of these tissue on the stress and strain of the neighboring tissues when the hea...
Abstract—Aneurysms of the cerebral arteries have potential risk of rupture which leads to intracr... more Abstract—Aneurysms of the cerebral arteries have potential risk of rupture which leads to intracranial hemorrhage that could be fatal. Nearly 1 to 5 percent of population has cerebral aneurysm; however 50 to 80 percent of these cases never face rupture of cerebral arteries ...
Blunt head impact arising from vehicular collisions, sporting injuries, and falls leads to relati... more Blunt head impact arising from vehicular collisions, sporting injuries, and falls leads to relative motion between the brain and skull and an increase in contact and shear stresses in the meningeal region, and leading to traumatic brain injuries. While there have been many finite element studies of the brain/head models there are limited analytical models. The goal of the present paper is to mathematically model subarachnoid space (SAS) and the meningeal layers and to investigate the motion of the brain relative to the skull, and their damping characteristics, during blunt head impacts. Based on the experimental studies of Hardy et al [6] the elasticity of the springs and damping constants of the dashpots were determined. The nonlinear governing integro-differential equations were formed and solved. The results of the analytical method are validated by performing an explicit finite element analysis. Acceptable agreement between these two methods is observed. The elastic deformation ...
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