scholarly journals Multi-Body Dynamic Analysis of Cervical Spine for Helicopter Pilots

2021 ◽  
Author(s):  
Hojjat Fathollahi
Keyword(s):  
Cervical Spine ◽  
Dynamic Model ◽  
Night Vision ◽  
Cervical Disc ◽  
Published Data ◽  
Lateral Bending ◽  
Flexion Extension ◽  
Helicopter Pilots ◽  
Multi Body ◽  
Body Dynamic

Helicopter pilots use helmets equipped with night vision goggle and counter weight. This increased load can lead to disc injury, so it is necessary to evaluate the load and moments applied to each cervical disc when pilot head is moving in different flight conditions. A 3D multi-body dynamic model of cervical spine is provided to investigate the effect of weight of the helmet in flexion, extension, lateral bending and axial rotation of the spine. The whole study was done in several steps: 1) to develop a non-linear dynamic model of spine. 2) to validate the model against the published data under flexion, extension, lateral bending and torsinal moments. 3) to solve three case studies to simulate a moving head in different direction. 4) to run the simulations again with consideration of adding a helmet into the model with different weight to find out the effects on the cervical discs loading. The results demonstrate that C2C3, C4C5 and C7T1 carry the highest loads depending on direction of imposed displacement on the head. Experts in the area of neck injury can study the results and locate the regions at risk of injury or they can feed this information into FEA model to get stress distribution in discs, bones or ligaments.

scholarly journals Multi-Body Dynamic Analysis of Cervical Spine for Helicopter Pilots

2021 ◽  
Author(s):  
Hojjat Fathollahi
Keyword(s):  
Cervical Spine ◽  
Dynamic Model ◽  
Night Vision ◽  
Cervical Disc ◽  
Published Data ◽  
Lateral Bending ◽  
Flexion Extension ◽  
Helicopter Pilots ◽  
Multi Body ◽  
Body Dynamic

Helicopter pilots use helmets equipped with night vision goggle and counter weight. This increased load can lead to disc injury, so it is necessary to evaluate the load and moments applied to each cervical disc when pilot head is moving in different flight conditions. A 3D multi-body dynamic model of cervical spine is provided to investigate the effect of weight of the helmet in flexion, extension, lateral bending and axial rotation of the spine. The whole study was done in several steps: 1) to develop a non-linear dynamic model of spine. 2) to validate the model against the published data under flexion, extension, lateral bending and torsinal moments. 3) to solve three case studies to simulate a moving head in different direction. 4) to run the simulations again with consideration of adding a helmet into the model with different weight to find out the effects on the cervical discs loading. The results demonstrate that C2C3, C4C5 and C7T1 carry the highest loads depending on direction of imposed displacement on the head. Experts in the area of neck injury can study the results and locate the regions at risk of injury or they can feed this information into FEA model to get stress distribution in discs, bones or ligaments.

Prediction of in vivo lower cervical spinal loading using musculoskeletal multi-body dynamics model during the head flexion/extension, lateral bending and axial rotation

2018 ◽  
Vol 232 (11) ◽  
pp. 1071-1082 ◽  
Author(s):  
Hao Diao ◽  
Hua Xin ◽  
Zhongmin Jin
Keyword(s):  
Cervical Spine ◽  
Axial Rotation ◽  
Intervertebral Disk ◽  
Lateral Bending ◽  
Spinal Loading ◽  
Flexion Extension ◽  
Body Dynamics ◽  
Head Flexion ◽  
Multi Body

Cervical spine diseases lead to a heavy economic burden to the individuals and societies. Moreover, frequent post-operative complications mean a higher risk of neck pain and revision. At present, controversy still exists for the etiology of spinal diseases and their associated complications. Knowledge of in vivo cervical spinal loading pattern is proposed to be the key to answer these questions. However, direct acquisition of in vivo cervical spinal loading remains challenging. In this study, a previously developed cervical spine musculoskeletal multi-body dynamics model was utilized for spinal loading prediction. The in vivo dynamic segmental contributions to head motion and the out-of-plane coupled motion were both taken into account. First, model validation and sensitivity analysis of different segmental contributions to head motion were performed. For model validation, the predicted intervertebral disk compressive forces were converted into the intradiskal pressures and compared with the published experimental measurements. Significant correlations were found between the predicted values and the experimental results. Thus, the reliability and capability of the cervical spine model was ensured. Meanwhile, the sensitivity analysis indicated that cervical spinal loading is sensitive to different segmental contributions to head motion. Second, the compressive, shear and facet joint forces at C3–C6 disk levels were predicted, during the head flexion/extension, lateral bending and axial rotation. Under the head flexion/extension movement, asymmetric loading patterns of the intervertebral disk were obtained. In comparison, symmetrical typed loading patterns were found for the head lateral bending and axial rotation movements. However, the shear forces were dramatically increased during the head excessive extension and lateral bending. Besides, a nonlinear correlation was seen between the facet joint force and the angular displacement. In conclusion, dynamic cervical spinal loading was both intervertebral disk angle-dependent and level-dependent. Cervical spine musculoskeletal multi-body dynamics model provides an attempt to comprehend the in vivo biomechanical surrounding of the human head-neck system.

A Biomechanical Evaluation of Whiplash Using a Multi-Body Dynamic Model

2003 ◽  
Vol 125 (2) ◽  
pp. 254-265 ◽  
Author(s):  
Tanya Garcia ◽  
Bahram Ravani
Keyword(s):  
Cervical Spine ◽  
Dynamic Model ◽  
Sagittal Plane ◽  
Separation Distance ◽  
Head Orientation ◽  
Model Response ◽  
Biomechanical Evaluation ◽  
Multi Body ◽  
Body Dynamic ◽  
Injury Potential

This paper presents a biomechanical evaluation of whiplash injury potential during the initial extension motion of the head in a rear-end collision. A four-segment dynamic model is developed in the sagittal plane for the analysis. The model response is validated using the existing experimental data and is shown to simulate the “S-shape” kinematics of the cervical spine and the resulting dynamics observed in human and cadaver experiments. The model is then used to evaluate the effects of parameters such as collision severity, head/headrest separation, and the initial head orientation in the sagittal plane on the “S-shape” kinematics of the cervical spine and the resulting neck loads. It is shown, for example, that the cervical spine forms an “S-shape” for a range of change in speeds and that at lower and higher speeds changes the spine does not form the “S-shape.” Furthermore, it is shown that the “S-shape” formation also depends on the head to headrest separation distance.

In vitro evaluation of a ball-and-socket cervical disc prosthesis with cranial geometric center

2009 ◽  
Vol 11 (5) ◽  
pp. 538-546 ◽  
Author(s):  
Cédric Barrey ◽  
Thomas Mosnier ◽  
Jérôme Jund ◽  
Gilles Perrin ◽  
Wafa Skalli
Keyword(s):  
Cervical Spine ◽  
Axial Rotation ◽  
Cervical Disc ◽  
Disc Prosthesis ◽  
Lateral Bending ◽  
Flexion Extension ◽  
Cervical Disc Prosthesis ◽  
Before And After ◽  
Left And Right

Object Few biomechanical in vitro studies have reported the effects of disc replacement on motion and kinematics of the cervical spine. The purpose of this study was to analyze motion through 3D load-displacement curves before and after implantation of a ball-and-socket cervical disc prosthesis with cranial geometric center; special focus was placed on coupled motion, which is a well-known aspect of normal cervical spine kinematics. Methods Six human cervical spines were studied. There were 3 male and 3 female cadaveric specimens (mean age at death 68.5 ± 5 years [range 54–74 years]). The specimens were evaluated sequentially in 2 different conditions: first they were tested intact; then the spinal specimens were tested after implantation of a ball-and-socket cervical disc prosthesis, the Discocerv, at the C5–6 level. Pure moment loading was applied in flexion/extension, left and right axial rotation, and left and right lateral bending. All tests were performed under load control with a 3D measurement system. Results No differences were found to be statistically significant after comparison of range of motion between intact and instrumented spines for all loading conditions. The mean range of motion for intact spines was 10.3° in flexion/extension, 5.6° in lateral bending, and 5.4° in axial rotation; that for instrumented spines was 10.4, 5.2, and 4.8°, respectively. No statistical difference was observed for the neutral zone nor stiffness between intact and instrumented spines. Finally, the coupled motions were also preserved during axial rotation and lateral bending, with no significant difference before and after implantation. Conclusions This study demonstrated that, under specific testing conditions, a ball-and-socket joint with cranial geometrical center can restore motion in the 3 planes after discectomy in the cervical spine while maintaining physiological coupled motions during axial rotation and lateral bending.

In vitro flexibility of the cervical spine after ventral uncoforaminotomy

2007 ◽  
Vol 7 (5) ◽  
pp. 537-541 ◽  
Author(s):  
Kirsten Schmieder ◽  
Annette Kettner ◽  
Christopher Brenke ◽  
Albrecht Harders ◽  
Ioannis Pechlivanis ◽  
...  
Keyword(s):  
Cervical Spine ◽  
Axial Rotation ◽  
Cervical Disc ◽  
Strong Increase ◽  
Lateral Bending ◽  
Mineral Density ◽  
Prosthetic Devices ◽  
Flexion Extension ◽  
The Impact

Object Degenerative spine disorders are, in the majority of cases, treated with ventral discectomy followed by fusion (also known as anterior cervical discectomy and fusion). Currently, nonfusion strategies are gaining broader acceptance. The introduction of cervical disc prosthetic devices was a natural consequence of this development. Jho proposed anterior uncoforaminotomy as an alternative motion-preserving procedure at the cervical spine. The clinical results in the literature are controversial, with one focus of disagreement being the impact of the procedure on stability. The aim of this study was to address the changes in spinal stability after uncoforaminotomy. Methods Six spinal motion segments derived from three fresh-frozen human cervical spine specimens (C2–7) were tested. The donors were two men whose ages at death were 59 and 80 years and one woman whose age was 80 years. Bone mineral density in C-3 ranged from 155 to 175 mg/cm3. The lower part of the segment was rigidly fixed in the spine tester, whereas the upper part was fixed in gimbals with integrated stepper motors. Pure moment loads of ± 2.5 Nm were applied in flexion/extension, axial rotation, and lateral bending. For each specimen a load-deformation curve, the range of motion (ROM), and the neutral zone (NZ) for negative and positive directions of motion were calculated. Median, maximum, and minimum values were calculated for the six segments and normalized to the intact segment. Tests were done on the intact segment, after unilateral uncoforaminotomy, and after bilateral uncoforaminotomy. Results In lateral bending a strong increase in ROM and NZ was detectable after unilateral uncoforaminotomy on the right side. Overall, the ROM during flexion/extension was less influenced after uncoforaminotomy. The ROM and NZ during axial rotation to the left increased strongly after right unilateral uncoforaminotomy. Changes after bilateral uncoforaminotomy were marked during axial rotation to both sides. Conclusions Following unilateral uncoforaminotomy, a significant alteration in mobility of the segment is found, especially during lateral bending and axial rotation. The resulting increase in mobility is less pronounced during flexion and least evident on extension. Further investigations of the natural course of disc degeneration and the impact on mobility after uncoforaminotomy are needed.

A PARAMETRIC INVESTIGATION OF THE EFFECTS OF CERVICAL DISC PROSTHESES WITH UPWARD AND DOWNWARD NUCLEI ON SPINE BIOMECHANICS

2016 ◽  
Vol 16 (07) ◽  
pp. 1650092 ◽  
Author(s):  
ZEINAB KAMAL ◽  
GHOLAMREZA ROUHI
Keyword(s):  
Cervical Spine ◽  
Axial Rotation ◽  
Torsional Stiffness ◽  
Cervical Disc ◽  
Fe Model ◽  
Lateral Bending ◽  
Biomechanical Behavior ◽  
Flexion Extension ◽  
Spinal Segments ◽  
Ct Data

This work aimed at investigating the influence of Baguera and Discocerv cervical disc prostheses, with mobile downward center of rotation (COR) and fixed upward COR, respectively, on the biomechanical behavior of C4–C6 cervical spine. For this purpose, using computed tomography (CT) data, a parametric nonlinear finite element (FE) model of intact C4–C6 spinal segments was developed, and an artificial disc was implanted at C5–C6 level. To assess the influence of implants on the biomechanics of cervical spine, the FE models were analyzed in flexion, extension, lateral bending, and axial rotation, and the results were presented in the range of motion (ROM) curves, and torsional stiffness. Results of this study, in agreement with the literature, suggested that both Baguera and Discocerv implants might be able to preserve the motion, and limit the alteration of the biomechanics of adjacent levels. Except for the possible confliction of adjacent vertebrae at the implanted level with Baguera implant in lateral bending, results of this study also indicated that the movability and downward COR of Baguera disc prosthesis caused ROMs of the implanted segment to be more similar to the intact model than Discocerv implant. Moreover, the upward COR of Discocerv implant may result in over-distraction on facets in the maximal flexion, with the ratio of 1.22 versus 1.36, and consequently facet syndrome during extension for Bageura and Discocerv disc prostheses, respectively.

scholarly journals Complications of cervical spine manipulation therapy: 5-year retrospective study in a single-group practice

2002 ◽  
Vol 13 (6) ◽  
pp. 1-8 ◽  
Author(s):  
David G. Malone ◽  
Nevan G. Baldwin ◽  
Frank J. Tomecek ◽  
Christopher M. Boxell ◽  
Steven E. Gaede ◽  
...  
Keyword(s):  
Cervical Spine ◽  
Disc Herniation ◽  
Spinal Manipulation ◽  
Cervical Disc ◽  
Published Data ◽  
Complication Rates ◽  
Single Group ◽  
Expected Number ◽  
Manipulation Therapy ◽  
Number Of Patients

Object The authors report a series of 22 patients in whom major complications developed after cervical spinal manipulation therapy (CSMT). A second objective was to estimate the regional incidence of these complications and to compare it with the very low incidences reported in the literature. Methods During a 5-year period, practioners at a single group neurosurgical practice in Tulsa, Oklahoma, treated 22 patients, who were markedly worse during, or immediately after, CSMT. The details of these cases are reported. The 1995 US Government National Census was used to define the regional referral population for Tulsa. The published data regarding the incidence of serious CSMT-related complications and the rate of CSMTs undertaken nationally were used to estimate the expected number of CSMT-related complications in the authors' region. The number (22 cases) reported in this series was used to estimate the actual regional incidence. Complications in the series included radiculopathy (21 cases), myelopathy (11 cases), Brown–Séquard syndrome (two cases), and vertebral artery (VA) occlusion (one case). Twenty-one patients underwent surgery. Poor outcomes were observed in three, outcome was unchanged in one, and 17 improved. The number of patients in this series exceeded the expected number for the region. Conclusions Cervical spinal manipulation therapy may worsen preexisting cervical disc herniation or cause disc herniation resulting in radiculopathy, myelopathy, or VA compression. In cases of cervical spondylosis, CSMT may also worsen preexisting myelopathy or radiculopathy. Manipulation of the cervical spine may also be associated with higher complication rates than previously reported.

FEBio finite element model of a pediatric cervical spine

2021 ◽  
pp. 1-7
Author(s):  
Sean M. Finley ◽  
J. Harley Astin ◽  
Evan Joyce ◽  
Andrew T. Dailey ◽  
Douglas L. Brockmeyer ◽  
...  
Keyword(s):  
Finite Element ◽  
Cervical Spine ◽  
Finite Element Model ◽  
Material Properties ◽  
Surgical Simulation ◽  
Element Model ◽  
Axial Stiffness ◽  
Published Data ◽  
Axial Tension ◽  
Flexion Extension

OBJECTIVE The underlying biomechanical differences between the pediatric and adult cervical spine are incompletely understood. Computational spine modeling can address that knowledge gap. Using a computational method known as finite element modeling, the authors describe the creation and evaluation of a complete pediatric cervical spine model. METHODS Using a thin-slice CT scan of the cervical spine from a 5-year-old boy, a 3D model was created for finite element analysis. The material properties and boundary and loading conditions were created and model analysis performed using open-source software. Because the precise material properties of the pediatric cervical spine are not known, a published parametric approach of scaling adult properties by 50%, 25%, and 10% was used. Each scaled finite element model (FEM) underwent two types of simulations for pediatric cadaver testing (axial tension and cardinal ranges of motion [ROMs]) to assess axial stiffness, ROM, and facet joint force (FJF). The authors evaluated the axial stiffness and flexion-extension ROM predicted by the model using previously published experimental measurements obtained from pediatric cadaveric tissues. RESULTS In the axial tension simulation, the model with 50% adult ligamentous and annulus material properties predicted an axial stiffness of 49 N/mm, which corresponded with previously published data from similarly aged cadavers (46.1 ± 9.6 N/mm). In the flexion-extension simulation, the same 50% model predicted an ROM that was within the range of the similarly aged cohort of cadavers. The subaxial FJFs predicted by the model in extension, lateral bending, and axial rotation were in the range of 1–4 N and, as expected, tended to increase as the ligament and disc material properties decreased. CONCLUSIONS A pediatric cervical spine FEM was created that accurately predicts axial tension and flexion-extension ROM when ligamentous and annulus material properties are reduced to 50% of published adult properties. This model shows promise for use in surgical simulation procedures and as a normal comparison for disease-specific FEMs.

scholarly journals Hydrodynamic Analysis of Self-Propulsion Performance of Wave-Driven Catamaran

2021 ◽  
Vol 9 (11) ◽  
pp. 1221
Author(s):  
Weixin Zhang ◽  
Ye Li ◽  
Yulei Liao ◽  
Qi Jia ◽  
Kaiwen Pan
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Dynamic Model ◽  
Dynamic Structure ◽  
Ocean Waves ◽  
Static State ◽  
Small Surface ◽  
Propulsion Performance ◽  
Multi Body ◽  
Body Dynamic

The wave-driven catamaran is a small surface vehicle driven by ocean waves. It consists of a hull and hydrofoils, and has a multi-body dynamic structure. The process of moving from static state to autonomous navigation driven by ocean waves is called “self-propulsion”, and reflects the ability of the wave-driven catamaran to absorb oceanic wave energy. Considering the importance of the design of the wave-driven catamaran, its self-propulsion performance should be comprehensively analysed. However, the wave-driven catamaran’s multi-body dynamic structure, unpredictable dynamic and kinematic responses driven by waves make it difficult to analyse its self-propulsion performance. In this paper, firstly, a multi-body dynamic model is established for wave-driven catamaran. Secondly, a two-phase numerical flow field containing water and air is established. Thirdly, a numerical simulation method for the self-propulsion process of the wave-driven catamaran is proposed by combining the multi-body dynamic model with a numerical flow field. Through numerical simulation, the hydrodynamic response, including the thrust of the hydrofoils, the resistance of the hull and the sailing velocity of the wave-driven catamaran are identified and comprehensively analysed. Lastly, the accuracy of the numerical simulation results is verified through a self-propulsion test in a towing tank. In contrast with previous research, this method combines multi-body dynamics with computational fluid dynamics (CFD) to avoid errors caused by artificially setting the motion mode of the catamaran, and calculates the real velocity of the catamaran.

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