The Experts below are selected from a list of 318 Experts worldwide ranked by ideXlab platform
Jos Vander Sloten - One of the best experts on this subject based on the ideXlab platform.
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Skull Fracture prediction through subject specific finite element modelling is highly sensitive to model parameters
Journal of The Mechanical Behavior of Biomedical Materials, 2019Co-Authors: Dries De Kegel, Bart Depreitere, Alexander Meynen, Nele Famaey, Harry G Van Lenthe, Jos Vander SlotenAbstract:Abstract Reliable computer models are needed for a better understanding of the physical mechanisms of Skull Fracture in accidental hits, falls, bicycle - motor vehicle & car accidents and assaults. The performance and biofidelity of these models depend on the correct anatomical representation and material description of these structures. In literature, a strain energy criterion has been proposed to predict Skull Fractures. However, a broad range of values for this criterion has been reported. This study investigates if the impactor orientation, scalp thickness and material model of the Skull could provide us with insight in the influencing factors of this criterion. 18 Skull Fracture experiments previously performed in our research group were reproduced in finite element simulations. Subject-specific Skull geometries were derived from medical images and used to create high-quality finite element meshes. Based on local Hounsfield units, a subject-specific isotropic material model was assigned. The subject-specific models were able to predict Fractures who matched visually with the corresponding experimental Fracture patterns and provided detailed Fracture patterns. The sensitivity study showed that small variations in impactor positioning as well as variations of the local geometry (frontal-temporal-occipital) strongly influenced the Skull strain energy. Subject-specific modelling leads to a more accurate prediction of the force-displacement curve. The average error of the peak Fracture force for all the 18 cases is 0.4190 for the subject-specific and 0.4538 for the homogeneous material model, for the displacement; 0.3368 versus 0.3844. But it should be carefully interpreted as small variations in the computational model significantly influence the outcome.
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biomechanics of frontal Skull Fracture
Journal of Neurotrauma, 2007Co-Authors: Hans Delye, Peter Verschueren, Bart Depreitere, Daniel Berckmans, Ignace Verpoest, G Van Der Perre, Jos Vander Sloten, Jan GoffinAbstract:The main purpose of the present study was to investigate whether an energy failure level would apply to the Skull Fracture mechanics in unembalmed post mortem human heads under dynamic frontal loading conditions. A double-pendulum set-up was used to conduct frontal impact tests on specimens from eight unembalmed post mortem human subjects. The specimens were isolated at the occipital condyle level and pre-test computed tomography images were obtained. The specimens were rigidly attached to an aluminum pendulum in an upside down position and obtained a single degree of freedom, allowing motion in the plane of impact. A steel pendulum delivered the impact and was fitted with a flat-surfaced, cylindrical aluminum impactor, which distributed the load to a force sensor. The relative displacement between the two pendulums was measured using a laser sensor and used as a measure for the deformation of the specimen in the plane of impact. Two impact velocity conditions were created: low (3.60±0.24 m/s) or high (5.18±0.04m/s) velocity. Computed tomography and dissection techniques were used to detect pathology. If no Fracture was detected, repeated tests on the same specimen were performed with higher impact energy until Fracture occurred. Eventually all specimens were Fractured. Peak force, displacement and energy variables were used to describe the biomechanics. These preliminary data suggest a positive correlation between impact velocity and energy to Fracture. Further experiments are necessary to elucidate the possibility of an energy criterion for Skull Fracture in head impacts.
Yuji Nikaido - One of the best experts on this subject based on the ideXlab platform.
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persistent intracranial hypertension caused by superior sagittal sinus stenosis following depressed Skull Fracture case report and review of the literature
Journal of Neurosurgery, 2006Co-Authors: Hiroshi Yokota, Takahiko Eguchi, Misato Nobayashi, Toshikazu Nishioka, Fumihiko Nishimura, Yuji NikaidoAbstract:Intracranial hypertension caused by a compound depressed Skull Fracture on the posterior part of the superior sagittal sinus is a rare condition, and nonspecific symptoms and signs can delay appropriate diagnosis and treatment. The authors report on a case of intracranial hypertension that persisted despite conservative treatment, including anticoagulation therapy, which did not improve severe flow disturbance related to the venous sinus compression. Management of this rare condition is discussed and the literature is reviewed.
Canan Akman - One of the best experts on this subject based on the ideXlab platform.
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depressed Skull Fracture overlying the superior sagittal sinus as a cause of benign intracranial hypertension case report
Journal of Neurosurgery, 1998Co-Authors: Mustafa Uzan, Nejat Ciplak, S Reza G Dashti, Hakan Bozkus, Pamir Erdincler, Canan AkmanAbstract:✓ The use of surgical treatment for depressed Skull Fractures that are located over major venous sinuses is a matter of controversy. However, if clinical and radiological findings of sinus obliteration and related intracranial hypertension are present, surgical decompression is indicated. The authors present the case of a 38-year-old man who had a depressed Skull Fracture overlying the posterior one-third portion of the superior sagittal sinus. The lesion was initially treated conservatively and the patient was readmitted 1 month later with signs and symptoms of intracranial hypertension. The role of radiological investigation in the detection of venous sinus flow and indications for surgical treatment are discussed. If venous sinus flow obstruction is revealed in the presence of signs and symptoms of intracranial hypertension, surgery is indicated as the first line of treatment.
Bart Depreitere - One of the best experts on this subject based on the ideXlab platform.
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Skull Fracture prediction through subject specific finite element modelling is highly sensitive to model parameters
Journal of The Mechanical Behavior of Biomedical Materials, 2019Co-Authors: Dries De Kegel, Bart Depreitere, Alexander Meynen, Nele Famaey, Harry G Van Lenthe, Jos Vander SlotenAbstract:Abstract Reliable computer models are needed for a better understanding of the physical mechanisms of Skull Fracture in accidental hits, falls, bicycle - motor vehicle & car accidents and assaults. The performance and biofidelity of these models depend on the correct anatomical representation and material description of these structures. In literature, a strain energy criterion has been proposed to predict Skull Fractures. However, a broad range of values for this criterion has been reported. This study investigates if the impactor orientation, scalp thickness and material model of the Skull could provide us with insight in the influencing factors of this criterion. 18 Skull Fracture experiments previously performed in our research group were reproduced in finite element simulations. Subject-specific Skull geometries were derived from medical images and used to create high-quality finite element meshes. Based on local Hounsfield units, a subject-specific isotropic material model was assigned. The subject-specific models were able to predict Fractures who matched visually with the corresponding experimental Fracture patterns and provided detailed Fracture patterns. The sensitivity study showed that small variations in impactor positioning as well as variations of the local geometry (frontal-temporal-occipital) strongly influenced the Skull strain energy. Subject-specific modelling leads to a more accurate prediction of the force-displacement curve. The average error of the peak Fracture force for all the 18 cases is 0.4190 for the subject-specific and 0.4538 for the homogeneous material model, for the displacement; 0.3368 versus 0.3844. But it should be carefully interpreted as small variations in the computational model significantly influence the outcome.
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biomechanics of frontal Skull Fracture
Journal of Neurotrauma, 2007Co-Authors: Hans Delye, Peter Verschueren, Bart Depreitere, Daniel Berckmans, Ignace Verpoest, G Van Der Perre, Jos Vander Sloten, Jan GoffinAbstract:The main purpose of the present study was to investigate whether an energy failure level would apply to the Skull Fracture mechanics in unembalmed post mortem human heads under dynamic frontal loading conditions. A double-pendulum set-up was used to conduct frontal impact tests on specimens from eight unembalmed post mortem human subjects. The specimens were isolated at the occipital condyle level and pre-test computed tomography images were obtained. The specimens were rigidly attached to an aluminum pendulum in an upside down position and obtained a single degree of freedom, allowing motion in the plane of impact. A steel pendulum delivered the impact and was fitted with a flat-surfaced, cylindrical aluminum impactor, which distributed the load to a force sensor. The relative displacement between the two pendulums was measured using a laser sensor and used as a measure for the deformation of the specimen in the plane of impact. Two impact velocity conditions were created: low (3.60±0.24 m/s) or high (5.18±0.04m/s) velocity. Computed tomography and dissection techniques were used to detect pathology. If no Fracture was detected, repeated tests on the same specimen were performed with higher impact energy until Fracture occurred. Eventually all specimens were Fractured. Peak force, displacement and energy variables were used to describe the biomechanics. These preliminary data suggest a positive correlation between impact velocity and energy to Fracture. Further experiments are necessary to elucidate the possibility of an energy criterion for Skull Fracture in head impacts.
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a new test set up for Skull Fracture characterisation
Journal of Biomechanics, 2007Co-Authors: Peter Verschueren, Hans Delye, Bart Depreitere, C Van Lierde, Bart Haex, Daniel Berckmans, Ignace Verpoest, Jan Goffin, Vander J Sloten, G Van Der PerreAbstract:Skull Fracture is a frequently observed type of severe head injury. Historically, a variety of impact test set-ups and techniques have been used for investigating Skull Fracture. The most frequently used are the free-fall technique, the guided fall or drop tower set-up and the piston-driven impactor set-up. This document proposes a new type of set-up for cadaver head impact testing which combines the strengths of the most frequently used techniques and devices. The set-up consists of two pendulums, which allow for a 1 degree of freedom rotational motion. The first pendulum is the impactor and is used to strike the blow. The head is attached to the second pendulum using a polyester resin. Local Skull deformation and impact force are measured with a sample frequency of 65 kHz. From these data, absorbed energy until Skull Fracture is calculated. A set-up evaluation consisting of 14 frontal Skull and head impact tests shows an accurate measurement of both force and local Skull deformation until Fracture of the Skull. Simplified mechanical models are used to analyse the different impacting techniques from literature as well as the new proposed set-up. It is concluded that the proposed test set-up is able to accurately calculate the energy absorbed by the Skull until Fracture with an uncertainty interval of 10%. Second, it is concluded that Skull Fracture caused by blunt impact occurs before any significant motion of the head. The two-pendulum set-up is the first head impact device to allow a well-controlled measurement environment without altering the Skull stress distribution.
Rémy Willinger - One of the best experts on this subject based on the ideXlab platform.
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development of Skull Fracture criterion based on real world head trauma simulations using finite element head model
Journal of The Mechanical Behavior of Biomedical Materials, 2016Co-Authors: Debasis Sahoo, Caroline Deck, Narayan Yoganandan, Rémy WillingerAbstract:The objective of this study was to enhance an existing finite element (FE) head model with composite modeling and a new constitutive law for the Skull. The response of the state-of-the-art FE head model was validated in the time domain using data from 15 temporo-parietal impact experiments, conducted with postmortem human surrogates. The new model predicted Skull Fractures observed in these tests. Further, 70 well-documented head trauma cases were reconstructed. The 15 experiments and 70 real-world head trauma cases were combined to derive Skull Fracture injury risk curves. The Skull internal energy was found to be the best candidate to predict Skull failure based on an in depth statistical analysis of different mechanical parameters (force, Skull internal energy), head kinematic-based parameter, the head injury criterion (HIC), and Skull Fracture correlate (SFC). The proposed tolerance limit for 50% risk of Skull Fracture was associated with 453mJ of internal energy. Statistical analyses were extended for individual impact locations (frontal, occipital and temporo-parietal) and separate injury risk curves were obtained. The 50% risk of Skull Fracture for each location: frontal: 481mJ, occipital: 457mJ, temporo-parietal: 456mJ of Skull internal energy.
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Anisotropic composite human Skull model and Skull Fracture validation against temporo-parietal Skull Fracture.
Journal of the mechanical behavior of biomedical materials, 2013Co-Authors: Debasis Sahoo, Caroline Deck, Narayan Yoganandan, Rémy WillingerAbstract:A composite material model for Skull, taking into account damage is implemented in the Strasbourg University finite element head model (SUFEHM) in order to enhance the existing Skull mechanical constitutive law. The Skull behavior is validated in terms of Fracture patterns and contact forces by reconstructing 15 experimental cases. The new SUFEHM Skull model is capable of reproducing Skull Fracture precisely. The composite Skull model is validated not only for maximum forces, but also for lateral impact against actual force time curves from PMHS for the first time. Skull strain energy is found to be a pertinent parameter to predict the Skull Fracture and based on statistical (binary logistical regression) analysis it is observed that 50% risk of Skull Fracture occurred at Skull strain energy of 544.0mJ.