scholarly journals The biomechanical effect of preexisting different types of disc herniation in cervical hyperextension injury

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Jian-jie Wang ◽  
Meng-lei Xu ◽  
Hui-zi Zeng ◽  
Liang-dong Zheng ◽  
Shi-jie Zhu ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Disc Herniation ◽  
Cervical Spinal Cord ◽  
Neutral Position ◽  
Fe Model ◽  
Diffuse Type ◽  
Local Type ◽  
Different Types ◽  
Von Mises ◽  
Von Mises Stresses

Abstract Objective Preexisting severe cervical spinal cord compression is a significant risk factor in cervical hyperextension injury, and the neurological function may deteriorate after a slight force to the forehead. There are few biomechanical studies regarding the influence of pathological factors in hyperextension loading condition. The aim of this study is to analyze the effects of preexisting different types of cervical disc herniation and different degrees of compression on the spinal cord in cervical hyperextension. Method A 3D finite element (FE) model of cervical spinal cord was modeled. Local type with median herniation, local type with lateral herniation, diffuse type with median herniation, and diffuse type with lateral herniation were simulated in neutral and extention positions. The compressions which were equivalent to 10%, 20%, 30%, and 40% of the sagittal diameter of the spinal cord were modeled. Results The results of normal FE model were consistent with those of previous studies. The maximum von Mises stresses appeared in the pia mater for all 32 loading conditions. The maximum von Mises stresses in extension position were much higher than in neutral position. In most cases, the maximum von Mises stresses in diffuse type were higher than in local type. Conclusion Cervical spinal cord with preexisting disc herniation is more likely to be compressed in hyperextension situation than in neutral position. Diffuse type with median herniation may cause more severe compression with higher von Mises stresses concentrated at the anterior horn and the peripheral white matter, resulting in acute central cord syndrome from biomechanical point of view.

THE BIOMECHANICAL EFFECTS OF CEMENT AUGMENTATION AND PARTIAL VERTEBRAL HEIGHT RESTORATION ON THE LOAD TRANSFER CHANGE OF ADJACENT VERTEBRAE IN VERTEBROPLASTY

2015 ◽  
Vol 15 (03) ◽  
pp. 1550025 ◽  
Author(s):  
CHIEN-YU LIN ◽  
WENG-PIN CHEN ◽  
PO-LIANG LAI ◽  
SHIH-YOUENG CHUANG ◽  
DA-TONG JU ◽  
...  
Keyword(s):  
Load Transfer ◽  
Cement Augmentation ◽  
Erector Spinae ◽  
Von Mises Stress ◽  
Fe Model ◽  
Vertebral Height ◽  
Adjacent Disc ◽  
Before And After ◽  
Von Mises ◽  
Von Mises Stresses

Vertebroplasty is commonly used to treat vertebral wedge fractures (VWFs). However, differing degrees of vertebral height restoration (VHR) have been reported after vertebroplasty, and little is known about how grades (steepness) of VWF deformities affect loadings on the fractured and adjacent unfractured vertebrae. Therefore, the goal of this study was to create a non-linear finite element (FE) model of the T10–L2 thoracolumbar segments. With this model, we aimed to evaluate the biomechanical outcomes of three different collapse models (25%, 50%, and 75%) at the T12 vertebra before and after cement augmentation (CA) and with and without VHR. In these VWF simulations, the forces of the erector spinae, the intradiscal pressure, and the maximum von Mises stresses in the endplates and vertebral bodies increased as vertebral deformation increased. Performing CA alone, without restoring vertebral height for the fractured vertebra, did not change the stiffness of multiple spinal segments or the pressures on the adjacent disc, but it did decrease stresses on the endplates and the vertebral bone. A 10% restoration of vertebral height after CA reduced the maximum von Mises stress in the endplates and bone structures more than when CA did not restore vertebral height (no VHR). These results suggest that achieving partial VHR during vertebroplasty may help prevent postvertebroplasty fractures in the fractured and adjacent vertebrae.

Finite Element Study of Spinal Cord Mechanics During Biomechanical Response of Middle Cervical Spine

2010 ◽  
Author(s):  
N. Bahramshahi ◽  
H. Ghaemi ◽  
K. Behdinan
Keyword(s):  
Spinal Cord ◽  
Cervical Spine ◽  
Stress Concentration ◽  
Cervical Spinal Cord ◽  
Axial Strain ◽  
Compressive Load ◽  
Fe Model ◽  
Local Pressure ◽  
Disc Space ◽  
Flexion Extension

The present study is conducted to develop a detailed FE model of spinal cord and to study its behaviour under various loading conditions. To achieve the goal, a previously developed and validated FE model of the middle cervical spine (C3-C5) is utilized. The model is further modified to investigate the stresses that the spinal cord in experiences during cervical spine motion segment in compression and flexion/extension loading modes. The resulting Von Misses stress and axial strain of the anterior and posterior surfaces of the cervical spinal cord are obtained from a set of elements along the C4-C5 disc space of the dural sheath, CSF and cord. The results show that in compression, the anterior surface of spinal cord experiences larger displacement, stress, and strain than those of the posterior surface. Conversely, the analyses show that in flexion\extension, the stresses, strains, and displacements are more pronounced in posterior segment of the spinal cord. In extension, the posterior disc bulge applies pressure onto the Posterior Longitudinal Ligament and thereby, applying local pressure on the spinal cord. The FE results show a stress concentration at the point of contact between disc and spinal cord. Furthermore, the FE results of flexion test show similar stress concentration characteristic at the point of contact. However, the local stress on spinal cord is more pronounced in flexion than extension at the C4-C5 area of spinal cord. It was also determined the compressive load resulted in the highest stress concentration on the spinal cord.

Spinal Cord Stress and Strain Predictions in a Ligamentous C5-C6 Segment

2000 ◽  
Author(s):  
J. Scifert ◽  
K. Totoribe ◽  
V. Goel ◽  
C. Clark ◽  
J. Reinhardt ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Spinal Cord Injury ◽  
Cervical Spinal Cord ◽  
Experimental Studies ◽  
Stress And Strain ◽  
Fe Model ◽  
Spinal Disorders ◽  
Significant Damage ◽  
Cord Injury ◽  
Bony Segment

Abstract Several spinal disorders and traumatic loading situations are known to inflict damage to neurovascular components of the cervical spinal cord. Studies have shown that damage to the spinal cord can occur regardless of significant damage to surrounding structures. To understand the mechanics of spinal cord injury, one needs to quantify stresses and strains within the spinal cord and its components in response to exterrnal loads applied to the bony spine. Experimental studies can not address this issue. This study presents a Finite Element (FE) model to quantify the physiologic strains and stresses in the cervical spinal cord placed in the ligamentous C5-C6 motion segment, with loads applied to the bony segment and not the the cord itself, as have been done in experimental studies reported in the literature.

Postlaminectomy cervical spinal cord compression demonstrated by dynamic magnetic resonance imaging

1998 ◽  
Vol 88 (1) ◽  
pp. 155-157 ◽  
Author(s):  
Tetsuya Morimoto ◽  
Hiroyuki Ohtsuka ◽  
Toshisuke Sakaki ◽  
Masahiko Kawaguchi
Keyword(s):  
Spinal Cord ◽  
Magnetic Resonance ◽  
Mr Imaging ◽  
Spinal Cord Compression ◽  
Cervical Myelopathy ◽  
Cervical Spinal Cord ◽  
Cord Compression ◽  
Neutral Position ◽  
Dynamic Magnetic Resonance ◽  
Canal Stenosis

✓ This 32-year-old man had undergone C3–7 laminectomy for posttraumatic cervical myelopathy associated with spinal canal stenosis. He developed recurrent myelopathy 5 years after the initial operation. Dynamic magnetic resonance (MR) imaging of the cervical spine demonstrated spinal cord compression with diffuse canal stenosis while the neck was in the extended position, whereas no significant stenosis was visualized in the neutral position. Sagittal and axial MR images of the affected levels demonstrated striking changes in the cervical spinal cord configuration. Because of an associated hard osteophyte formation and protruded disc, as well as a hypertrophied posterior longitudinal ligament, an anterior decompression and fusion with plate fixation were performed from C-4 to C-7. The postoperative course was uneventful, with subsequent neurological improvement. It is concluded that dynamic MR imaging aids the search for the cause of recurrent postlaminectomy cervical myelopathy after initial improvement following decompressive surgery.

Biomechanical Behaviors in Three Types of Spinal Cord Injury Mechanisms

2016 ◽  
Vol 138 (8) ◽  
Author(s):  
Batbayar Khuyagbaatar ◽  
Kyungsoo Kim ◽  
Won Man Park ◽  
Yoon Hyuk Kim
Keyword(s):  
Spinal Cord ◽  
Principal Strain ◽  
Von Mises Stress ◽  
Fe Model ◽  
Maximum Principal Strain ◽  
Stress Peak ◽  
Peak Maximum ◽  
Injury Mechanisms ◽  
Cord Injury ◽  
Von Mises

Clinically, spinal cord injuries (SCIs) are radiographically evaluated and diagnosed from plain radiographs, computed tomography (CT), and magnetic resonance imaging. However, it is difficult to conclude that radiographic evaluation of SCI can directly explain the fundamental mechanism of spinal cord damage. The von-Mises stress and maximum principal strain are directly associated with neurological damage in the spinal cord from a biomechanical viewpoint. In this study, the von-Mises stress and maximum principal strain in the spinal cord as well as the cord cross-sectional area (CSA) were analyzed under various magnitudes for contusion, dislocation, and distraction SCI mechanisms, using a finite-element (FE) model of the cervical spine with spinal cord including white matter, gray matter, dura mater with nerve roots, and cerebrospinal fluid (CSF). A regression analysis was performed to find correlation between peak von-Mises stress/peak maximum principal strain at the cross section of the highest reduction in CSA and corresponding reduction in CSA of the cord. Dislocation and contusion showed greater peak stress and strain values in the cord than distraction. The substantial increases in von-Mises stress as well as CSA reduction similar to or more than 30% were produced at a 60% contusion and a 60% dislocation, while the maximum principal strain was gradually increased as injury severity elevated. In addition, the CSA reduction had a strong correlation with peak von-Mises stress/peak maximum principal strain for the three injury mechanisms, which might be fundamental information in elucidating the relationship between radiographic and mechanical parameters related to SCI.

Effects of acetabular resurfacing component material and fixation on the strain distribution in the pelvis

2002 ◽  
Vol 216 (4) ◽  
pp. 237-245 ◽  
Author(s):  
M S Thompson ◽  
M D Northmore-Ball ◽  
K E Tanner
Keyword(s):  
Cancellous Bone ◽  
Reaction Force ◽  
Hip Resurfacing ◽  
Heel Strike ◽  
Bone Strain ◽  
Fe Model ◽  
Joint Reaction Force ◽  
Cortical Shell ◽  
Von Mises ◽  
Von Mises Stresses

A 3D finite element (FE) model of an implanted pelvis was developed as part of a project investigating an all-polymer hip resurfacing design. The model was used to compare this novel design with a metal-on-metal design in current use and a metal-on-polymer design typical of early resurfacing implants. The model included forces representing the actions of 22 muscles as well as variable cancellous bone stiffness and variable cortical shell thickness. The hip joint reaction force was applied via contact modelled between the femoral and acetabular components of the resurfacing prosthesis. Five load cases representing time points through the gait cycle were analysed. The effect of varying fixation conditions was also investigated. The highest cancellous bone strain levels were found at mid-stance, not heel-strike. Remote from the acetabulum there was little effect of prosthesis material and fixation upon the von Mises stresses and maximum principal strains. Implant material appeared to have little effect upon cancellous bone strain failure with both bonded and unbonded bone-implant interfaces. The unbonded implants increased stresses in the subchondral bone at the centre of the acetabulum and increased cancellous bone loading, resembling behaviour obtained previously for the intact acetabulum.

Study of Different Biomaterials for Artificial Lumbar Disc Prosthesis Using FEM

2015 ◽  
Vol 799-800 ◽  
pp. 483-487
Author(s):  
Fátima Somovilla Gómez ◽  
Ruben Lostado Lorza ◽  
Marina Corral Bobadilla ◽  
Luis María López González ◽  
José Antonio Gómez Cristobal ◽  
...  
Keyword(s):  
Finite Element ◽  
Lumbar Disc ◽  
Fe Model ◽  
Disc Prosthesis ◽  
Artificial Disc ◽  
Cocrmo Alloy ◽  
Suitable Material ◽  
Flexion Moment ◽  
Von Mises ◽  
Von Mises Stresses

The purpose of this study was to analyze the behavior of a lumbar spine disc prosthesis with different materials. The study was performed at L4-L5 lumbar motion segment using the finite element method (FEM). A healthy Finite Element (FE) model was used as a reference with which to compare the results of the FE simulations of the artificial discs. The healthy and the artificial FE models were subjected to a combination of 0.5 MPa Compression pre-load and 10Nm of Flexion moment. The artificial FE models were based on Maverick artificial disc, and the three materials proposed for study the artificial disk were Titanium, Ceramic and CrCoMo alloy. The most suitable material for developed the artificial disc was the CoCrMo alloy due to: The von Mises stresses on the bone with which this artificial disc was in contact were reduced as much as possible and also, were very similar to the von Mises stresses obtained in the bones from the healthy disc.

scholarly journals Finite element simulations of the effects of an extraoral device, RAMPA, on anterosuperior protraction of the maxilla and comparison with gHu-1 intraoral device

2021 ◽  
Author(s):  
Mohammad Moshfeghi ◽  
Yasushi Mitani ◽  
Bumkyoo Choi ◽  
Peiman Emamy
Keyword(s):  
Finite Element ◽  
Fe Model ◽  
Maxillary Expansion ◽  
Lateral Direction ◽  
Positive Effects ◽  
Intraoral Device ◽  
Nodal Displacements ◽  
Von Mises ◽  
External Forces ◽  
Von Mises Stresses

ABSTRACT Objectives To investigate the effects of an extraoral device, right-angle maxillary protraction appliance (RAMPA), combined with a semi-rapid maxillary expansion intraoral device (gHu-1) on the anterosuperior protraction of maxillary bone. Materials and Methods The finite element (FE) model included craniofacial bones and all sutures. The linear assumption was assumed for the FE simulations and the material properties of bones and sutures. The gHu-1 was simulated under screw activations equal to Δx = 0.25 and 0.5 mm in the lateral direction with and without RAMPA under a set of external forces {F1 = 2.94, F2 = 1.47, F3 = 4.44} N. Results Displacement contours, nodal displacements of 12 landmarks, and von Mises stresses were compared. Combining RAMPA and gHu-1 (with Δx = 0.25 mm) resulted in changes in the displacement of the front part of the maxilla near the mid-palatal suture from (0.02, −0.1, −0.02) mm to (0.02, 0.3, 0.8) mm. For gHu-1 with Δx = 0.5 mm, the displacement of the same part changed from (0.04, −0.04, −0.2) mm to (0.04, 0.3, 0) mm. Similar trends were found in other locations. Conclusions The findings are in agreement with the previous cephalometric clinical data of an 8-year-old patient and prove the positive effects of RAMPA on the anterosuperior protraction of the maxilla when it is combined with the intraoral device gHu-1. In addition, RAMPA does not interfere with the lateral expansion generated by the intraoral device.

scholarly journals Biomechanical Effects of Lateral Bending Position on Performing Cervical Spinal Manipulation for Cervical Disc Herniation: A Three-Dimensional Finite Element Analysis

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Xuecheng Huang ◽  
Linqiang Ye ◽  
Zixian Wu ◽  
Lichang Liang ◽  
Qianli Wang ◽  
...  
Keyword(s):  
Finite Element ◽  
Disc Herniation ◽  
Spinal Manipulation ◽  
Facet Joint ◽  
Cervical Disc ◽  
Disc Displacement ◽  
Neutral Position ◽  
Fe Model ◽  
Lateral Bending ◽  
Fiber Stress

Background. Most studies report that the common position of cervical spinal manipulation (CSM) for treating symptomatic cervical disc herniation (CDH) is lateral bending to the herniated side. However, the rationality of lateral bending position on performing CSM for CDH is still unclear. Objective. The purpose of this study is to investigate the biomechanical effects of lateral bending position on performing CSM for CDH. Methods. A finite element (FE) model of CDH (herniated on the left side) was generated in C5-6 segment based on the normal FE model. The FE model performed CSM in left lateral bending position, neutral position, and right lateral bending position, respectively. Cervical disc displacement, annulus fiber stress, and facet joint stress were observed during the simulation of CSM. Results. The cervical disc displacement on herniated side moved forward during CSM, and the maximum forward displacements were 0.23, 0.36, and 0.45 mm in left lateral bending position, neutral position, and right lateral bending position, respectively. As the same trend of cervical disc displacement, the annulus fiber stresses on herniated side from small to large were 7.40, 16.39, and 22.75 MPa in left lateral bending position, neutral position, and right lateral bending position, respectively. However, the maximum facet stresses at left superior cartilage of C6 in left lateral bending position, neutral position, and right lateral bending position were 6.88, 3.60, and 0.12 MPa, respectively. Conclusion. Compared with neutral position and right lateral bending position, though the forward displacement of cervical disc on herniated side was smaller in left lateral bending position, the annulus fiber stress on herniated side was declined by sharing load on the left facet joint. The results suggested that lateral bending to the herniated side on performing CSM tends to protect the cervical disc on herniated side. Future clinical studies are needed to verify that.

scholarly journals Effects of cervical rotatory manipulation on the cervical spinal cord: a finite element study

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Fan Xue ◽  
Zujiang Chen ◽  
Han Yang ◽  
Taijun Chen ◽  
Yikai Li
Keyword(s):  
Spinal Cord ◽  
Finite Element ◽  
Cervical Spinal Cord ◽  
Von Mises Stress ◽  
Published Data ◽  
Fe Model ◽  
Cross Sectional ◽  
Flexion Extension ◽  
Cord Injury

Abstract Background Little information is available concerning the biomechanism involved in the spinal cord injury after cervical rotatory manipulation (CRM). The primary purpose of this study was to explore the biomechanical and kinematic effects of CRM on a healthy spinal cord. Methods A finite element (FE) model of the basilaris cranii, C1–C7 vertebral bodies, nerve root complex and vertebral canal contents was constructed and validated against in vivo and in vitro published data. The FE model simulated CRM in the flexion, extension and neutral positions. The stress distribution, forma and relative position of the spinal cord were observed. Results Lower von Mises stress was observed on the spinal cord after CRM in the flexion position. The spinal cord in CRM in the flexion and neutral positions had a lower sagittal diameter and cross-sectional area. In addition, the spinal cord was anteriorly positioned after CRM in the flexion position, while the spinal cord was posteriorly positioned after CRM in the extension and neutral positions. Conclusion CRM in the flexion position is less likely to injure the spinal cord, but caution is warranted when posterior vertebral osteophytes or disc herniations exist.

Sign in / Sign up

Export Citation Format

Share Document