scholarly journals Subject-Specific Inverse Dynamics of the Head and Cervical Spine During in Vivo Dynamic Flexion-Extension

2013 ◽  
Vol 135 (6) ◽  
Author(s):  
William J. Anderst ◽  
William F. Donaldson ◽  
Joon Y. Lee ◽  
James D. Kang
Keyword(s):  
Finite Element ◽  
Cervical Spine ◽  
Inverse Dynamics ◽  
Total Force ◽  
Finite Element Models ◽  
Moment Arms ◽  
Flexion Extension ◽  
Subject Specific

The effects of degeneration and surgery on cervical spine mechanics are commonly evaluated through in vitro testing and finite element models derived from these tests. The objectives of the current study were to estimate the load applied to the C2 vertebra during in vivo functional flexion-extension and to evaluate the effects of anterior cervical arthrodesis on spine kinetics. Spine and head kinematics from 16 subjects (six arthrodesis patients and ten asymptomatic controls) were determined during functional flexion-extension using dynamic stereo X-ray and conventional reflective markers. Subject-specific inverse dynamics models, including three flexor muscles and four extensor muscles attached to the skull, estimated the force applied to C2. Total force applied to C2 was not significantly different between arthrodesis and control groups at any 10 deg increment of head flexion-extension (all p values ≥ 0.937). Forces applied to C2 were smallest in the neutral position, increased slowly with flexion, and increased rapidly with extension. Muscle moment arms changed significantly during flexion-extension, and were dependent upon the direction of head motion. The results suggest that in vitro protocols and finite element models that apply constant loads to C2 do not accurately represent in vivo cervical spine kinetics.

Subject-specific finite element models of long bones: An in vitro evaluation of the overall accuracy

2006 ◽  
Vol 39 (13) ◽  
pp. 2457-2467 ◽  
Author(s):  
Fulvia Taddei ◽  
Luca Cristofolini ◽  
Saulo Martelli ◽  
H.S. Gill ◽  
Marco Viceconti
Keyword(s):  
Finite Element ◽  
Finite Element Models ◽  
Long Bones ◽  
In Vitro Evaluation ◽  
Subject Specific

Effect of a Degenerated C5-C6 Disc on the Biomechanics of Adjacent Levels: A Poroelastic Finite Element Investigation

2007 ◽  
Author(s):  
Mozammil Hussain ◽  
Raghu N. Natarajan ◽  
Gunnar B. J. Andersson ◽  
Howard S. An
Keyword(s):  
Finite Element ◽  
Cervical Spine ◽  
Morphological Changes ◽  
Axial Strain ◽  
Fe Model ◽  
Fe Method ◽  
Regional Effect ◽  
In Vitro Techniques

Degenerative changes in the cervical spine due to aging are very common causes of neck pain in general population. Although many investigators have quantified the gross morphological changes in the disc with progressive degeneration, the biomechanical changes due to degenerative pathologies of the disc and its effect on the adjacent levels are not well understood. Despite many in vivo and in vitro techniques used to study such complex phenomena, the finite element (FE) method is still a powerful tool to investigate the internal mechanics and complex clinical situations under various physiological loadings particularly when large numbers of parameters are involved. The objective of the present study was to develop and validate a poroelastic FE model of a healthy C3-T1 segment of the cervical spine under physiologic moment loads. The model included the regional effect of change in the fixed charged density of proteoglycan concentration and change in the permeability and porosity due to change in the axial strain of disc tissues. The model was further modified to include various degrees of disc degeneration at the C5-C6 level. Outcomes of this study provided a better understanding on the progression of degeneration along the cervical spine by investigating the biomechanical response of the adjacent segments with an intermediate degenerated C5-C6 level.

scholarly journals Shear Wave Predictions of Achilles Tendon Loading during Human Walking

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Emily M. Keuler ◽  
Isaac F. Loegering ◽  
Jack A. Martin ◽  
Joshua D. Roth ◽  
Darryl G. Thelen
Keyword(s):  
Achilles Tendon ◽  
Shear Wave ◽  
Wave Speed ◽  
Inverse Dynamics ◽  
Human Walking ◽  
Cross Sectional ◽  
Moment Arms ◽  
Subject Specific ◽  
S Peak

Abstract The evaluation of in vivo muscle-tendon loads is fundamental to understanding the actuation of normal and pathological human walking. However, conventional techniques for measuring muscle-tendon loads in the human body are too invasive for use in gait analysis. Here, we demonstrate the use of noninvasive measures of shear wave propagation as a proxy for Achilles tendon loading during walking. Twelve healthy young adults performed isometric ankle plantarflexion on a dynamometer. Achilles tendon wave speed, tendon moment arms, tendon cross-sectional area and ankle torque were measured. We first showed that the linear relationship between tendon stress and wave speed squared can be calibrated from isometric tasks. There was no significant effect of knee angle, ankle angle or loading rate on the subject-specific calibrations. Calibrated shear wave tensiometers were used to estimate Achilles tendon loading when walking at speeds ranging from 1 to 2 m/s. Peak tendon stresses during pushoff increased from 41 to 48 MPa as walking speed was increased, and were comparable to estimates from inverse dynamics. The tensiometers also detected Achilles tendon loading of 4 to 7 MPa in late swing. Late swing tendon loading was not discernible in the inverse dynamics estimates, but did coincide with passive stretch of the gastrocnemius muscle-tendon units. This study demonstrates the capacity to use calibrated shear wave tensiometers to evaluate tendon loading in locomotor tasks. Such technology could prove beneficial for identifying the muscle actions that underlie subject-specific movement patterns.

Isolating the effects of equine hoof shape measurements on capsule strain with finite element analysis

2003 ◽  
Vol 16 (02) ◽  
pp. 67-75 ◽  
Author(s):  
H. L. McClinchey ◽  
J. C. Jofriet ◽  
J. J. Thomason
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Finite Element Methods ◽  
In Vivo Studies ◽  
Finite Element Models ◽  
Element Analysis ◽  
Toe Angle ◽  
Equine Hoof

SummaryThe shape of the equine hoof capsule affects how weightbearing forces are resisted by the capsule and are transmitted to deeper structures within the hoof. Our aim was to isolate the effects of several measurements describing hoof shape on strains and stresses in the hoof capsule. Multiple finite-element models are constructed with toe angles in the range 42° to 58°, heel angles from 34° to 50°, toe lengths of 8.5 to11.5 cm, and medial and lateral angles from 68° to 83°. Strain at the toe is inversely related to toe angle, and not strongly affected by heel angle; it increases with toe length distally on the toe, but decreases near the coronary border. Varying medial and lateral angles show that more upright walls have less strain at the quarters. This study demonstrates the effectiveness of finite element methods in complementing in vitro and in vivo studies of hoof mechanics.

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.

Estimating lumbar passive stiffness behaviour from subject-specific finite element models and in vivo 6DOF kinematics

2020 ◽  
Vol 102 ◽  
pp. 109681 ◽  
Author(s):  
Christian Affolter ◽  
Joanna Kedzierska ◽  
Thomas Vielma ◽  
Bernhard Weisse ◽  
Ameet Aiyangar
Keyword(s):  
Finite Element ◽  
Finite Element Models ◽  
Passive Stiffness ◽  
Subject Specific

Experimental flexion/extension data corridors for validation of finite element models of the young, normal cervical spine

2006 ◽  
Vol 39 (2) ◽  
pp. 375-380 ◽  
Author(s):  
John A. Wheeldon ◽  
Frank A. Pintar ◽  
Stephanie Knowles ◽  
Narayan Yoganandan
Keyword(s):  
Finite Element ◽  
Cervical Spine ◽  
Finite Element Models ◽  
Flexion Extension

scholarly journals Numerical Modelling of the Behaviour of the Cervical Spine under the Effect of a Flexion / Extension

2019 ◽  
Vol 01 (02) ◽  
pp. 144-153 ◽  
Author(s):  
Nadir Damba ◽  
Abdellatif OUDRANE ◽  
Benaoumeur AOUR ◽  
Mohammed Salah BENNOUNA ◽  
Nabil BELKAHELLA ◽  
...  
Keyword(s):  
Cervical Spine ◽  
Classical Mechanics ◽  
Three Dimensional ◽  
Individual Variability ◽  
In Vitro Tests ◽  
Three Dimensional Model ◽  
Major Interest ◽  
Flexion Extension

Numerical simulation is today widely used in several fields of engineering, and research undertaken for more than 20 years concerning the geometric and mechanical modeling of the spine gradually leads to clinical applications of major interest. Indeed, the in vivo and in vitro evaluation tools pose a certain number of limitations: non-standardized procedures and inter-specimen variability for in vitro tests, medical, ethical constraints, and inter-individual variability for in vivo. These limitations are actually obstacles to comparison. It is notably within the framework of implant comparisons that the methods of structural calculation, and more particularly finite element modeling, widely used in classical mechanics, find their usefulness. in this context, this present work consists in developing a three-dimensional model of the cervical spine, in order to subsequently optimize the fitting of disc prostheses

scholarly journals The biomechanical effect on the adjacent L4/L5 segment of S1 superior facet arthroplasty: a finite element analysis for the male spine

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Zewen Shi ◽  
Lin Shi ◽  
Xianjun Chen ◽  
Jiangtao Liu ◽  
Haihao Wu ◽  
...  
Keyword(s):  
Finite Element ◽  
Range Of Motion ◽  
Facet Joint ◽  
Adjacent Segment ◽  
Finite Element Models ◽  
Level Of Evidence ◽  
Element Analysis ◽  
Flexion Extension ◽  
Biomechanical Effect ◽  
Lumbar Range Of Motion

Abstract Background The superior facet arthroplasty is important for intervertebral foramen microscopy. To our knowledge, there is no study about the postoperative biomechanics of adjacent L4/L5 segments after different methods of S1 superior facet arthroplasty. To evaluate the effect of S1 superior facet arthroplasty on lumbar range of motion and disc stress of adjacent segment (L4/L5) under the intervertebral foraminoplasty. Methods Eight finite element models (FEMs) of lumbosacral vertebrae (L4/S) had been established and validated. The S1 superior facet arthroplasty was simulated with different methods. Then, the models were imported into Nastran software after optimization; 500 N preload was imposed on the L4 superior endplate, and 10 N⋅m was given to simulate flexion, extension, lateral flexion and rotation. The range of motion (ROM) and intervertebral disc stress of the L4-L5 spine were recorded. Results The ROM and disc stress of L4/L5 increased with the increasing of the proportions of S1 superior facet arthroplasty. Compared with the normal model, the ROM of L4/L5 significantly increased in most directions of motion when S1 superior facet formed greater than 3/5 from the ventral to the dorsal or 2/5 from the apex to the base. The disc stress of L4/L5 significantly increased in most directions of motion when S1 superior facet formed greater than 3/5 from the ventral to the dorsal or 1/5 from the apex to the base. Conclusion In this study, the ROM and disc stress of L4/L5 were affected by the unilateral S1 superior facet arthroplasty. It is suggested that the forming range from the ventral to the dorsal should be less than 3/5 of the S1 upper facet joint. It is not recommended to form from apex to base. Level of evidence Level IV

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