Influence of Laminotomies and Laminectomies on Cervical Spine Biomechanics under Combined Flexion-Extension

2004 ◽  
Vol 20 (3) ◽  
pp. 243-259 ◽  
Author(s):  
Hong-Wan Ng ◽  
Ee-Chon Teo ◽  
QingHang Zhang
Keyword(s):  
Cervical Spine ◽  
Surgical Techniques ◽  
Internal Stresses ◽  
Published Data ◽  
Spine Biomechanics ◽  
Element Analysis ◽  
Flexion Extension ◽  
Biomechanical Responses ◽  
Biomechanical Changes

Posterior decompressive techniques including one- and two-level laminotomies and laminectomies are often used in treating cervical stenosis. Previously, several in vitro studies were conducted to help us understand the biomechanical changes occurring in the cervical spine after these surgical techniques. However, changes in the intersegmental flexibility under combined flexion-extension remain unclear. In this study, a 3-D nonlinear intact model of the C2–C7 was developed to evaluate the influence of one- and two-level laminotomies and laminectomies on the intersegmental moment rotational responses and internal stresses. The intact model was validated by comparing the predicted responses against experimental data. The validated model was then modified to simulate various surgical techniques for finite element analysis. Results showed that one- and two-level laminectomies increase the C2–C7 rotation motions by about 15% and 20%, respectively. The predicted increase in rotational motions also correlated well with the published data. Furthermore, results indicated that laminectomies would influence the biomechanical responses on both the affected and adjacent motion segments. In contrast, laminotomies have no significant effects on cervical biomechanics. To conduct a one-level laminectomy study, current findings indicate that it takes at least five motion segments to capture the immediate postsurgical biomechanical changes accurately and realistically. Minimally invasive cervical spine surgeries with one- or two-level laminotomies are preferred over one- and two-level laminectomies. Also, there is no consideration as to the efficacy of the two techniques in decompressing the spinal cord or nerve roots, which is the goal of the surgery, but is not examined in this study.

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.

A Finite Element Analysis of the C2-C7 Sheep Spine

2010 ◽  
Author(s):  
Nicole A. DeVries ◽  
Nicole A. Kallemeyn ◽  
Kiran H. Shivanna ◽  
Nicole M. Grosland
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Surgical Techniques ◽  
In Vitro Studies ◽  
Element Analysis ◽  
Spinal Disorders ◽  
Biomechanical Responses ◽  
Experimental Biomechanics ◽  
Similarities And Differences

Due to the limited availability of human cadaveric specimens, sheep are often utilized for in vitro studies of various spinal disorders and surgical techniques. Understanding the similarities and differences between the human and sheep spine is crucial for constructing a valuable study and interpreting the results. Several studies have identified the anatomical similarities between the sheep and human spine; however these studies have been limited to quantifying the anatomic dimensions as opposed to the biomechanical responses [1–2]. Although anatomical similarities are important, biomechanical correspondence is imperative for studying the effects of disorders, surgical techniques, and implant designs. Studies by Wilke and colleagues [3] and Clarke et al. [4] have focused on experimental biomechanics of the sheep cervical functional spinal units (FSUs).

scholarly journals Finite element analysis of middle cervical spine

2021 ◽  
Author(s):  
Noushin Bahramshahi
Keyword(s):  
Spinal Cord ◽  
Finite Element ◽  
Cervical Spine ◽  
Three Dimensional ◽  
Spinal Column ◽  
Element Model ◽  
Published Data ◽  
Element Analysis ◽  
Flexion Extension ◽  
Disc Bulge

The spinal cord may be injured through various spinal column injury patterns. However, the relationship between column injury pattern and cord damage is not well understood. This investigation was conducted to develop a detailed, asymmetric three-dimensional finite element model of the C3-C5 cervical spine. The model was validated by comparing the simulation results obtained in this study with experimental published data. Upon validation of the model, the spinal cord was included into the model the simulation were performed. The disc bulge in the model with spinal cord were measured and compared with the results of the model without spinal cord. The results showed that inclusion of the spinal cord reduced the amount of lateral disc bulged. The results of the analysis of the model with spinal cord showed that in compression, the anterior surface of spinal cord sees more displacement, stress and strain that posterior surface and vice versa for flexion/extension.

scholarly journals Finite element analysis of middle cervical spine

2021 ◽  
Author(s):  
Noushin Bahramshahi
Keyword(s):  
Spinal Cord ◽  
Finite Element ◽  
Cervical Spine ◽  
Three Dimensional ◽  
Spinal Column ◽  
Element Model ◽  
Published Data ◽  
Element Analysis ◽  
Flexion Extension ◽  
Disc Bulge

The spinal cord may be injured through various spinal column injury patterns. However, the relationship between column injury pattern and cord damage is not well understood. This investigation was conducted to develop a detailed, asymmetric three-dimensional finite element model of the C3-C5 cervical spine. The model was validated by comparing the simulation results obtained in this study with experimental published data. Upon validation of the model, the spinal cord was included into the model the simulation were performed. The disc bulge in the model with spinal cord were measured and compared with the results of the model without spinal cord. The results showed that inclusion of the spinal cord reduced the amount of lateral disc bulged. The results of the analysis of the model with spinal cord showed that in compression, the anterior surface of spinal cord sees more displacement, stress and strain that posterior surface and vice versa for flexion/extension.

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.

In vitro 3D-kinematics of the upper cervical spine: helical axis and simulation for axial rotation and flexion extension

2009 ◽  
Vol 32 (2) ◽  
pp. 141-151 ◽  
Author(s):  
Pierre-Michel Dugailly ◽  
Stéphane Sobczak ◽  
Victor Sholukha ◽  
Serge Van Sint Jan ◽  
Patrick Salvia ◽  
...  
Keyword(s):  
Cervical Spine ◽  
Axial Rotation ◽  
Helical Axis ◽  
Upper Cervical Spine ◽  
3D Kinematics ◽  
Flexion Extension ◽  
Upper Cervical

Biomechanics of a posture-controlling cervical artificial disc: mechanical, in vitro, and finite-element analysis

2010 ◽  
Vol 28 (6) ◽  
pp. E11 ◽  
Author(s):  
Neil R. Crawford ◽  
Jeffery D. Arnett ◽  
Joshua A. Butters ◽  
Lisa A. Ferrara ◽  
Nikhil Kulkarni ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Cervical Spine ◽  
Postural Control ◽  
Range Of Motion ◽  
Computer Modeling ◽  
Mechanical Testing ◽  
Artificial Disc ◽  
Element Analysis

Different methods have been described by numerous investigators for experimentally assessing the kinematics of cervical artificial discs. However, in addition to understanding how artificial discs affect range of motion, it is also clinically relevant to understand how artificial discs affect segmental posture. The purpose of this paper is to describe novel considerations and methods for experimentally assessing cervical spine postural control in the laboratory. These methods, which include mechanical testing, cadaveric testing, and computer modeling studies, are applied in comparing postural biomechanics of a novel postural control arthroplasty (PCA) device versus standard ball-and-socket (BS) and ball-in-trough (BT) arthroplasty devices. The overall body of evidence from this group of tests supports the conclusion that the PCA device does control posture to a particular lordotic position, whereas BS and BT devices move freely through their ranges of motion.

Analysis of adjacent-segment cervical kinematics: the role of construct length and the dorsal ligamentous complex

2020 ◽  
Vol 32 (1) ◽  
pp. 15-22
Author(s):  
Daniel Lubelski ◽  
Andrew T. Healy ◽  
Prasath Mageswaran ◽  
Robb Colbrunn ◽  
Richard P. Schlenk
Keyword(s):  
Cervical Spine ◽  
Industrial Robot ◽  
Adjacent Segment ◽  
Segmental Motion ◽  
Lateral Mass ◽  
Subaxial Cervical Spine ◽  
Flexion Extension ◽  
Cervical Kinematics

OBJECTIVELateral mass fixation stabilizes the cervical spine while causing minimal morbidity and resulting in high fusion rates. Still, with 2 years of follow-up, approximately 6% of patients who have undergone posterior cervical fusion have worsening kyphosis or symptomatic adjacent-segment disease. Based on the length of the construct, the question of whether to extend the fixation system to undisrupted levels has not been answered for the cervical spine. The authors conducted a study to quantify the role of construct length and the terminal dorsal ligamentous complex in the adjacent-segment kinematics of the subaxial cervical spine.METHODSIn vitro flexibility testing was performed using 6 human cadaveric specimens (C2–T8), with the upper thoracic rib cage and osseous and ligamentous integrity intact. An industrial robot was used to apply pure moments and to measure segmental motion at each level. The authors tested the intact state, followed by 9 postsurgical permutations of laminectomy and lateral mass fixation spanning C2 to C7.RESULTSConstructs spanning a single level exerted no significant effects on immediate adjacent-segment motion. The addition of a second immobilized segment, however, created significant changes in flexion-extension range of motion at the supradjacent level (+164%). Regardless of construct length, resection of the terminal dorsal ligaments did not greatly affect adjacent-level motion except at C2–3 and C7–T1 (increasing by +794% and +607%, respectively).CONCLUSIONSDorsal ligamentous support was found to contribute significant stability to the C2–3 and C7–T1 segments only. Construct length was found to play a significant role when fixating two or more segments. The addition of a fused segment to support an undisrupted cervical level is not suggested by the present data, except potentially at C2–3 and C7–T1. The study findings emphasize the importance of the C2–3 segment and its dorsal support.

Kinematics of the Cervical Spine: Path of the Instant Axis of Rotation in Flexion and Extension

2000 ◽  
Author(s):  
Denis J. DiAngelo ◽  
Keith Vossel ◽  
Kevin T. Foley
Keyword(s):  
Cervical Spine ◽  
Vertebral Body ◽  
Measurement System ◽  
Axis Of Rotation ◽  
Rotational Components ◽  
Flexion Extension ◽  
Vertebral Kinematics ◽  
Set Up ◽  
Flexion And Extension

Abstract Previous Biomechanical Measures of Vertebral Kinematics. White and Panjabi (1990) have suggested that the Instant Axis of Rotation (IAR) be used to describe the 2-D motion of a vertebral body. However, the location of the IAR for the cervical spine varies amongst spine researchers. White and Panjabi (1990) have suggested the IAR of each vertebra is located in the anterior region of the subjacent vertebra; Porterfield and Derosa (1995) suggest it is located in the mid-region of the subjacent vertebra; and Mameren et al. (1992) found it to lay in the central region of the vertebral body being tracked. Goel and Winterbottom (1991) stated that during flexion and extension, the axis of rotation is located somewhere within the vertebral body itself. Unfortunately, no accurate calculations of the IAR paths of the cervical spine exist; typical vertebral measurements only include the rotational components. Estimation of the vertebrae’s IAR location in vitro depends on the experimental set-up (motion and loading mechanics), anatomical structure, mathematical reduction technique, and accuracy of the measurement equipment. Crisco et al. (1994) determined the theoretical error in calculating the location of the IAR as a function of the measurement system specifications and the placement of the markers on the spinal body. Conventional tracking systems having translational resolutions of 0.1mm to 0.05mm were found to calculate the location of the IAR to within 7mm to 10mm, respectively. This error became significantly larger as the resolution of the measurement system dropped off. Most investigators only calculate the rotational components of a body’s motion and seldom calculate the error involved in their mathematical analysis. Furthermore, overall head movement is often reported (i.e., C0 to T1), but smaller flexion-extension movements of individual spinal bodies are either void in the literature or suspect to large theoretical errors. The objective of the study was to determine the IAR of the sub-axial cervical vertebral bodies under physiological flexion and extension conditions in vitro.

Numerical investigation on the stability of human upper cervical spine (C1–C3)

2021 ◽  
pp. 1-13
Author(s):  
Waseem Ur Rahman ◽  
Wei Jiang ◽  
Guohua Wang ◽  
Zhijun Li
Keyword(s):  
Finite Element ◽  
Cervical Spine ◽  
Axial Rotation ◽  
Upper Cervical Spine ◽  
Fe Model ◽  
Facet Joints ◽  
Flexion Extension ◽  
Upper Cervical ◽  
The Stability

BACKGROUND: The finite element method (FEM) is an efficient and powerful tool for studying human spine biomechanics. OBJECTIVE: In this study, a detailed asymmetric three-dimensional (3D) finite element (FE) model of the upper cervical spine was developed from the computed tomography (CT) scan data to analyze the effect of ligaments and facet joints on the stability of the upper cervical spine. METHODS: A 3D FE model was validated against data obtained from previously published works, which were performed in vitro and FE analysis of vertebrae under three types of loads, i.e. flexion/extension, axial rotation, and lateral bending. RESULTS: The results show that the range of motion of segment C1–C2 is more flexible than that of segment C2–C3. Moreover, the results from the FE model were used to compute stresses on the ligaments and facet joints of the upper cervical spine during physiological moments. CONCLUSION: The anterior longitudinal ligaments (ALL) and interspinous ligaments (ISL) are found to be the most active ligaments, and the maximum stress distribution is appear on the vertebra C3 superior facet surface under both extension and flexion moments.

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