Structural Behavior of Human Lumbar Intervertebral Disc under Direct Shear

Schmidt, Hendrik; Häussler, K.; Wilke, Hans–Joachim; Wolfram, Uwe

doi:10.5301/jabfm.5000176

Cited by 10 publications

(9 citation statements)

References 22 publications

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“…The elastic modulus and Poisson’s ratio of the scalp were assumed based on the experimental data by Galford and McElhaney 21 and the viscous deformation was neglected. The material properties of the cervical discs were based on the test data by Schmidt et al; 22 the effects of the interstitial fluid were neglected. The same elastic material properties were applied to the skull and vertebral bone.…”

Section: Methodsmentioning

confidence: 99%

Finite element simulations of the head–brain responses to the top impacts of a construction helmet: Effects of the neck and body mass

Pan

Wimer

et al. 2016

Proc Inst Mech Eng H

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Traumatic brain injuries are among the most common severely disabling injuries in the United States. Construction helmets are considered essential personal protective equipment for reducing traumatic brain injury risks at work sites. In this study, we proposed a practical finite element modeling approach that would be suitable for engineers to optimize construction helmet design. The finite element model includes all essential anatomical structures of a human head (i.e. skin, scalp, skull, cerebrospinal fluid, brain, medulla, spinal cord, cervical vertebrae, and discs) and all major engineering components of a construction helmet (i.e. shell and suspension system). The head finite element model has been calibrated using the experimental data in the literature. It is technically difficult to precisely account for the effects of the neck and body mass on the dynamic responses, because the finite element model does not include the entire human body. An approximation approach has been developed to account for the effects of the neck and body mass on the dynamic responses of the head–brain. Using the proposed model, we have calculated the responses of the head–brain during a top impact when wearing a construction helmet. The proposed modeling approach would provide a tool to improve the helmet design on a biomechanical basis.

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Section: Methodsmentioning

confidence: 99%

Finite element simulations of the head–brain responses to the top impacts of a construction helmet: Effects of the neck and body mass

Pan

Wimer

et al. 2016

Proc Inst Mech Eng H

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“…41 reported 565,000 N/m in anterior shear and 366,000 N/m in posterior shear; Schmidt et al. 42 reported 490,000 N/m in the posterior–anterior direction and 110,000 N/m for the disc alone. These reported stiffness values were larger than the values presented in other reports.…”

Section: Discussionmentioning

confidence: 98%

Identification of damping and stiffness parameters of cervical and lumbar spines of supine humans under vertical whole-body vibration

Qiao

Rahmatalla

2019

Journal of Low Frequency Noise, Vibration and Active Control

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This work presents a methodology to estimate the unknown damping and stiffness parameters of supine humans at the cervical and lumbar regions while reducing errors presented in the data. Modal parameters (natural frequencies, damping ratios, and eigenvectors) determined from experiments on 11 supine-human subjects exposed to vertical whole-body vibration were used in an inverse modal problem to solve for physical parameters (stiffness and damping). Due to uncertainty in the error level in the modal data, a methodology is presented to reduce the error by correcting the phase of the eigenvectors. Constraints that preserve the inter-connectivity of the physical stiffness and damping matrices were utilized via semi-definite programming. A four-degree-of-freedom human model, as suggested by the experimental modal analysis, was used for computational and analysis purposes. The resulting damping and stiffness parameters of the cervical and lumbar regions produced the right structure of the stiffness and damping matrices and satisfied the equation of motion. Validation analysis on the predicted acceleration response in the time domain of the human model, using the resulting damping and stiffness parameters, demonstrated characteristics very close to those found by the experiments. This work presents new information with many potential applications to the field of biomechanics.

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“…The studies were repeated for the L 3 -L 4 , L 4 -L 5 , and L 5 -S 1 discs, as each has peculiar characteristics. For example, L 5 -S 1 discs have to support a higher shear force than the other two, 36 and the zygapophyseal joint shape and orientation are different for all of them. 37 …”

Section: Methodsmentioning

confidence: 99%

Finite Element Analysis of a Bionate Ring-Shaped Customized Lumbar Disc Nucleus Prosthesis

Vanaclocha

Atienza

et al. 2021

ACS Appl. Bio Mater.

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Study design : Biomechanical study of a nucleus replacement with a finite element model. Objective : To validate a Bionate 80A ring-shaped nucleus replacement. Methods : The ANSYS lumbar spine model made from lumbar spine X-rays and magnetic resonance images obtained from cadaveric spine specimens were used. All materials were assumed homogeneous, isotropic, and linearly elastic. We studied three options: intact spine, nucleotomy, and nucleus implant. Two loading conditions were evaluated at L 3 -L 4 , L 4 -L 5 , and L 5 -S 1 discs: a 1000 N axial compression load and this load after the addition of 8 Nm flexion moment in the sagittal plane plus 8 Nm axial rotation torque. Results : Maximum nucleus implant axial compression stresses in the range of 16–34 MPa and tensile stress in the range of 5–16 MPa, below Bionate 80A resistance were obtained. Therefore, there is little risk of permanent implant deformation or severe damage under normal loading conditions. Nucleotomy increased segment mobility, zygapophyseal joint and end plate pressures, and annulus stresses and strains. All these parameters were restored satisfactorily by nucleus replacement but never reached the intact status. In addition, annulus stresses and strains were lower with the nucleus implant than in the intact spine under axial compression and higher under complex loading conditions. Conclusions : Under normal loading conditions, there is a negligible risk of nucleus replacement, permanent deformation or severe damage. Nucleotomy increased segmental mobility, zygapophyseal joint pressures, and annulus stresses and strains. Nucleus replacement restored segmental mobility and zygapophyseal joint pressures close to the intact spine. End plate pressures were similar for the intact and nucleus implant conditions under both loading modes. Manufacturing customized nucleus implants is considered feasible, as satisfactory biomechanical performance is confirmed.

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Structural Behavior of Human Lumbar Intervertebral Disc under Direct Shear

Abstract: This study was an experiment to subject IVDs to direct shear. The results could help us to understand the structure and function of IVDs with regard to mechanical spinal stability, and they can be used to validate finite element models of the IVD.

Cited by 10 publications

References 22 publications

Finite element simulations of the head–brain responses to the top impacts of a construction helmet: Effects of the neck and body mass

Finite element simulations of the head–brain responses to the top impacts of a construction helmet: Effects of the neck and body mass

Identification of damping and stiffness parameters of cervical and lumbar spines of supine humans under vertical whole-body vibration

Finite Element Analysis of a Bionate Ring-Shaped Customized Lumbar Disc Nucleus Prosthesis

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