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.

In Vitro Study of the C2-C7 Sheep Cervical Spine

2011 ◽  
Author(s):  
Nicole A. DeVries ◽  
Anup A. Gandhi ◽  
Douglas C. Fredericks ◽  
Joseph D. Smucker ◽  
Nicole M. Grosland
Keyword(s):  
Cervical Spine ◽  
Surgical Techniques ◽  
In Vitro Study ◽  
Axial Rotation ◽  
Lateral Bending ◽  
Disc Space ◽  
Flexion Extension ◽  
Biomechanical Responses ◽  
Experimental Biomechanics

Due to the limited availability of human cadaveric specimens, animal models are often utilized for in vitro studies of various spinal disorders and surgical techniques. Sheep spines have similar geometry, disc space, and lordosis as compared to humans [1,2]. Several studies have identified the geometrical similarities between the sheep and human spine; however these studies have been limited to quantifying the anatomic dimensions as opposed to the biomechanical responses [2–3]. Although anatomical similarities are important, biomechanical correspondence is imperative to understand the effects of disorders, surgical techniques, and implant designs. Some studies [3–5] have focused on experimental biomechanics of the sheep cervical functional spinal units (FSUs). Szotek and colleagues [1] studied the biomechanics of compression and impure flexion-extension for the C2-C7 intact sheep spine. However, to date, there is no comparison of the sheep spine using pure flexion-extension, lateral bending, or axial rotation moments for multilevel specimen. Therefore, the purpose of this study was to conduct in vitro testing of the intact C2-C7 sheep cervical spine.

In vivo 3D kinematic changes in the cervical spine after laminoplasty for cervical spondylotic myelopathy

2014 ◽  
Vol 21 (3) ◽  
pp. 417-424 ◽  
Author(s):  
Yukitaka Nagamoto ◽  
Motoki Iwasaki ◽  
Tsuyoshi Sugiura ◽  
Takahito Fujimori ◽  
Yohei Matsuo ◽  
...  
Keyword(s):  
Cervical Spine ◽  
Cervical Spondylotic Myelopathy ◽  
Head Rotation ◽  
Upper Cervical Spine ◽  
Registration Method ◽  
Flexion Extension ◽  
Upper Cervical ◽  
Head Flexion ◽  
Age Range

Object Cervical laminoplasty is an effective procedure for decompressing the spinal cord at multiple levels, but restriction of neck motion is one of the well-known complications of the procedure. Although many authors have reported on cervical range of motion (ROM) after laminoplasty, they have focused mainly on 2D flexion and extension on lateral radiographs, not on 3D motion (including coupled motion) nor on precise intervertebral motion. The purpose of this study was to clarify the 3D kinematic changes in the cervical spine after laminoplasty performed to treat cervical spondylotic myelopathy. Methods Eleven consecutive patients (6 men and 5 women, mean age 68.1 years, age range 57–79 years) with cervical spondylotic myelopathy who had undergone laminoplasty were included in the study. All patients underwent 3D CT of the cervical spine in 5 positions (neutral, 45° head rotation left and right, maximum head flexion, and maximum head extension) using supporting devices. The scans were performed preoperatively and at 6 months after laminoplasty. Segmental ROM from Oc–C1 to C7–T1 was calculated both in flexion-extension and in rotation, using a voxel-based registration method. Results Mean C2–7 flexion-extension ROM, equivalent to cervical ROM in all previous studies, was 45.5° ± 7.1° preoperatively and 35.5° ± 8.2° postoperatively, which was a statistically significant 33% decrease. However, mean Oc–T1 flexion-extension ROM, which represented total cervical ROM, was 71.5° ± 8.3° preoperatively and 66.5° ± 8.3° postoperatively, an insignificant 7.0% decrease. In focusing on each motion segment, the authors observed a statistically significant 22.6% decrease in mean segmental ROM at the operated levels during flexion-extension and a statistically insignificant 10.2% decrease during rotation. The most significant decrease was observed at C2–3. Segmental ROM at C2–3 decreased 24.2% during flexion-extension and 21.8% during rotation. However, a statistically insignificant 37.2% increase was observed at the upper cervical spine (Oc–C2) during flexion-extension. The coupling pattern during rotation did not change significantly after laminoplasty. Conclusions In this first accurate documentation of 3D segmental kinematic changes after laminoplasty, Oc–T1 ROM, which represented total cervical ROM, did not change significantly during either flexion-extension or rotation by 6 months after laminoplasty despite a significant decrease in C2–7 flexion-extension ROM. This is thought to be partially because of a compensatory increase in segmental ROM at the upper cervical spine (Oc–C2).

Biomechanical comparison of anterior Caspar plate and three-level posterior fixation techniques in a human cadaveric model

1993 ◽  
Vol 79 (1) ◽  
pp. 96-103 ◽  
Author(s):  
Vincent C. Traynelis ◽  
Paul A. Donaher ◽  
Robert M. Roach ◽  
H. Kojimoto ◽  
Vijay K. Goel
Keyword(s):  
Cervical Spine ◽  
Repeated Measures ◽  
Plate Fixation ◽  
Axial Rotation ◽  
Posterior Fixation ◽  
Lateral Bending ◽  
Anterior Plate ◽  
Content Type ◽  
Cervical Spine Injuries ◽  
Flexion Extension

✓ Traumatic cervical spine injuries have been successfully stabilized with plates applied to the anterior vertebral bodies. Previous biomechanical studies suggest, however, that these devices may not provide adequate stability if the posterior ligaments are disrupted. To study this problem, the authors simulated a C-5 teardrop fracture with posterior ligamentous instability in human cadaveric spines. This model was used to compare the immediate biomechanical stability of anterior cervical plating, from C-4 to C-6, to that provided by a posterior wiring construct over the same levels. Stability was tested in six modes of motion: flexion, extension, right and left lateral bending, and right and left axial rotation. The injured/plate-stabilized spines were more stable than the intact specimens in all modes of testing. The injured/posterior-wired specimens were more stable than the intact spines in axial rotation and flexion. They were not as stable as the intact specimens in the lateral bending or extension testing modes. The data were normalized with respect to the motion of the uninjured spine and compared using repeated measures of analysis of variance, the results of which indicate that anterior plating provides significantly more stability in extension and lateral bending than does posterior wiring. The plate was more stable than the posterior construct in flexion loading; however, the difference was not statistically significant. The two constructs provide similar stability in axial rotation. This study provides biomechanical support for the continued use of bicortical anterior plate fixation in the setting of traumatic cervical spine instability.

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.

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.

The effect of spinal instrumentation on kinematics at the cervicothoracic junction: emphasis on soft-tissue response in an in vitro human cadaveric model

2010 ◽  
Vol 13 (4) ◽  
pp. 435-442 ◽  
Author(s):  
Ryan M. Kretzer ◽  
Nianbin Hu ◽  
Hidemasa Umekoji ◽  
Daniel M. Sciubba ◽  
George I. Jallo ◽  
...  
Keyword(s):  
Cervical Spine ◽  
Pedicle Screw ◽  
Axial Rotation ◽  
Cervical Region ◽  
Facet Joints ◽  
Lateral Bending ◽  
Cervicothoracic Junction ◽  
Thoracic Pedicle Screw ◽  
Flexion Extension ◽  
Intact Condition

Object Thoracic pedicle screw instrumentation is often indicated in the treatment of trauma, deformity, degenerative disease, and oncological processes. Although classic teaching for cervical spine constructs is to bridge the cervicothoracic junction (CTJ) when instrumenting in the lower cervical region, the indications for extending thoracic constructs into the cervical spine remain unclear. The goal of this study was to determine the role of ligamentous and facet capsule (FC) structures at the CTJ as they relate to stability above thoracic pedicle screw constructs. Methods A 6-degree-of-freedom spine simulator was used to test multidirectional range of motion (ROM) in 8 human cadaveric specimens at the C7–T1 segment. Flexion-extension, lateral bending, and axial rotation at the CTJ were tested in the intact condition, followed by T1–6 pedicle screw fixation to create a long lever arm inferior to the C7–T1 level. Multidirectional flexibility testing of the T1–6 pedicle screw construct was then sequentially performed after sectioning the C7–T1 supraspinous ligament/interspinous ligament (SSL/ISL) complex, followed by unilateral and bilateral FC disruption at C7–T1. Finally, each specimen was reconstructed using C5–T6 instrumented fixation and ROM testing at the CTJ performed as previously described. Results Whereas the application of a long-segment thoracic construct stopping at T-1 did not significantly increase flexion-extension peak total ROM at the supra-adjacent level, sectioning the SSL/ISL significantly increased flexibility at C7–T1, producing 35% more motion than in the intact condition (p < 0.05). Subsequent FC sectioning had little additional effect on ROM in flexion-extension. Surprisingly, the application of thoracic instrumentation had a stabilizing effect on the supra-adjacent C7–T1 segment in axial rotation, leading to a decrease in peak total ROM to 83% of the intact condition (p < 0.05). This is presumably due to interaction between the T-1 screw heads and titanium rods with the C7–T1 facet joints, thereby limiting axial rotation. Incremental destabilization served only to restore peak total ROM near the intact condition for this loading mode. In lateral bending, the application of thoracic instrumentation stopping at T-1, as well as SSL/ISL and FC disruption, demonstrated trends toward increased supraadjacent ROM; however, these trends did not reach statistical significance (p > 0.05). Conclusions When stopping thoracic constructs at T-1, care should be taken to preserve the SSL/ISL complex to avoid destabilization of the supra-adjacent CTJ, which may manifest clinically as proximal-junction kyphosis. In an analogous fashion, if a T-1 laminectomy is required for neural decompression or surgical access, consideration should be given to extending instrumentation into the cervical spine. Facet capsule disruption, as might be encountered during T-1 pedicle screw placement, may not be an acutely destabilizing event, due to the interaction of the C7–T1 facet joints with T-1 instrumentation.

Range of Motion of the Upper Cervical Spine: flexion, extension, lateral bending, and axial rotation

2020 ◽  
Vol 8 ◽  
Author(s):  
Ana I. Lorente ◽  
César Hidalgo García ◽  
Jacobo Rodríguez Sanz ◽  
Mario Maza Frechín ◽  
Albert Pérez Bellmunt
Keyword(s):  
Cervical Spine ◽  
Range Of Motion ◽  
Axial Rotation ◽  
Upper Cervical Spine ◽  
Lateral Bending ◽  
Normal Range ◽  
Range Of Movement ◽  
Flexion Extension ◽  
Upper Cervical ◽  
Life Threatening

Instability is a serious and life-threatening diagnosis in the upper cervical spine (occiput-atlas-axis), and a depth understanding of normal range of movement is required for clinical manual evaluation. To improve this knowledge, ten upper cervical spine specimens have been tested in flexion, extension, lateral bending, and axial rotation. 

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.

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