Mechanical Properties of Human Lumbar Spine Motion Segments—Part II: Responses in Compression and Shear; Influence of Gross Morphology

1979 ◽  
Vol 101 (1) ◽  
pp. 53-57 ◽  
Author(s):  
M. H. Berkson ◽  
A. Nachemson ◽  
A. B. Schultz
Keyword(s):  
Mechanical Behavior ◽  
Intervertebral Disk ◽  
Human Cadaver ◽  
Large Scatter ◽  
Lateral Bending ◽  
Lateral Shear ◽  
Human Lumbar Spine ◽  
Flexion Extension ◽  
Spine Motion ◽  
Anterior Posterior

In this second part of a three-part report, we consider the mechanical behavior of 42 fresh human cadaver lumbar motion segments in compression, and in anterior, posterior, and lateral shear. We report the motions and the intradiskal pressure increases that occurred with posterior elements both intact and destroyed. We also examine to what extent intervertebral disk gross morphology can explain the large scatter in the results presented here, as well as in the results reported in Part I concerning mechanical behavior in flexion, extension, lateral bending, and torsion.

Mechanical Properties of Human Lumbar Spine Motion Segments—Part I: Responses in Flexion, Extension, Lateral Bending, and Torsion

1979 ◽  
Vol 101 (1) ◽  
pp. 46-52 ◽  
Author(s):  
A. B. Schultz ◽  
D. N. Warwick ◽  
M. H. Berkson ◽  
A. L. Nachemson
Keyword(s):  
Mechanical Properties ◽  
Lumbar Spine ◽  
Mechanical Behavior ◽  
Human Cadaver ◽  
Lateral Bending ◽  
Human Lumbar Spine ◽  
Flexion Extension ◽  
Spine Motion ◽  
Pressure Changes ◽  
Posterior Elements

In this first part of a three-part report, the mechanical behavior of 42 fresh human cadaver lumbar motion segments in flexion, extension, lateral bending, and torsion is examined. Motions and intradiskal pressure changes that occurred in response to these loads, with posterior elements both intact and excised, are reported.

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.

Control of Different FEM Based Musculoskeletal Models of Human Lumbar Spine Under Different Loading Conditions Using Optimization Method

2006 ◽  
Author(s):  
A. Kiapour ◽  
M. Parnianpour ◽  
A. Shirazi-Adl
Keyword(s):  
Lumbar Spine ◽  
Optimization Methods ◽  
Optimization Method ◽  
Complex Model ◽  
Lateral Bending ◽  
Musculoskeletal Models ◽  
Human Lumbar Spine ◽  
Flexion Extension ◽  
Load Vector ◽  
Complex Architecture

In this study the effects of using different musculoskeletal models on load-displacement behavior of FE models of the human lumbar spine under external loads and moments have been analyzed in terms of equilibrium and clinical stability. A simplified and a complex architecture of muscles have been integrated to FE based models of lumbar spine and were loaded to simulate the load carrying behavior of human lumbar spine in flexion, extension and lateral bending. The displacement values as well as muscle forces have been computed and compared in both cases using optimization methods with different cost functions. The models showed similar kinematics in pure flexion but the simplified model showed instability in flexion-lateral bending and pure lateral bending conditions. The complex model was loaded and analyzed with different cost function and it was observed that displacements in the model are lower while the angle between the load vector and spine curvature at each level is minimized. It was shown that the model is less stable in case an asymmetric loading condition is applied.

scholarly journals The Influence of Kinematic Constraints on Model Performance During Inverse Kinematics Analysis of the Thoracolumbar Spine

2021 ◽  
Vol 9 ◽  
Author(s):  
Mohammad Mehdi Alemi ◽  
Katelyn A. Burkhart ◽  
Andrew C. Lynch ◽  
Brett T. Allaire ◽  
Seyed Javad Mousavi ◽  
...  
Keyword(s):  
Motion Analysis ◽  
Inverse Kinematics ◽  
Intraclass Correlation ◽  
Axial Rotation ◽  
Kinematics Analysis ◽  
Lateral Bending ◽  
Kinematic Constraints ◽  
Flexion Extension ◽  
Spine Motion ◽  
Rms Error

Motion analysis is increasingly applied to spine musculoskeletal models using kinematic constraints to estimate individual intervertebral joint movements, which cannot be directly measured from the skin surface markers. Traditionally, kinematic constraints have allowed a single spinal degree of freedom (DOF) in each direction, and there has been little examination of how different kinematic constraints affect evaluations of spine motion. Thus, the objective of this study was to evaluate the performance of different kinematic constraints for inverse kinematics analysis. We collected motion analysis marker data in seven healthy participants (4F, 3M, aged 27–67) during flexion–extension, lateral bending, and axial rotation tasks. Inverse kinematics analyses were performed on subject-specific models with 17 thoracolumbar joints allowing 51 rotational DOF (51DOF) and corresponding models including seven sets of kinematic constraints that limited spine motion from 3 to 9DOF. Outcomes included: (1) root mean square (RMS) error of spine markers (measured vs. model); (2) lag-one autocorrelation coefficients to assess smoothness of angular motions; (3) maximum range of motion (ROM) of intervertebral joints in three directions of motion (FE, LB, AR) to assess whether they are physiologically reasonable; and (4) segmental spine angles in static ROM trials. We found that RMS error of spine markers was higher with constraints than without (p < 0.0001) but did not notably improve kinematic constraints above 6DOF. Compared to segmental angles calculated directly from spine markers, models with kinematic constraints had moderate to good intraclass correlation coefficients (ICCs) for flexion–extension and lateral bending, though weak to moderate ICCs for axial rotation. Adding more DOF to kinematic constraints did not improve performance in matching segmental angles. Kinematic constraints with 4–6DOF produced similar levels of smoothness across all tasks and generally improved smoothness compared to 9DOF or unconstrained (51DOF) models. Our results also revealed that the maximum joint ROMs predicted using 4–6DOF constraints were largely within physiologically acceptable ranges throughout the spine and in all directions of motions. We conclude that a kinematic constraint with 5DOF can produce smooth spine motions with physiologically reasonable joint ROMs and relatively low marker error.

The Effect of the Thermoplastic Minerva Cervical Spine Motion

Neurosurgery ◽  
1989 ◽  
Vol 25 (3) ◽  
pp. 363-368 ◽  
Author(s):  
Dennis Maiman ◽  
Pamela Millington ◽  
Sue Novak ◽  
Julie Kerk ◽  
JoAnne Ellingsen ◽  
...  
Keyword(s):  
Cervical Spine ◽  
Healthy Male ◽  
Lateral Bending ◽  
Flexion Extension ◽  
Before And After ◽  
Spine Motion ◽  
Male Subjects ◽  
Cervical Rotation ◽  
Cervical Level

Abstract In order to determine the extent of cervical spine immobilization provided by the thermoplastic Minerva body jacket (TMBJ) 20 healthy male subjects underwent analysis of cervical spine motion before and after TMBJ placement. Maximal cervical flexion/extension and lateral bending were measured from lateral and anteroposterior roentgenograms, respectively. Maximal cervical rotation was measured from overhead photographs. The TMBJ significantly limited flexion/extension at each level of the cervical spine, as well as rotation and lateral bending (P< 0.001). Flexion/extension at each cervical level was found to be equal to that allowed by the halo with body jacket at most levels and less at the occiput-C1, C3-C4, and C6-C7 (as reported in studies using similar methodology). The present study suggests that the thermoplastic Minerva body jacket is a valuable option for rigid external immobilization of the cervical spine.

scholarly journals Annular Defects Impair the Mechanical Stability of the Intervertebral Disc

2021 ◽  
pp. 219256822110060
Author(s):  
Jun-Xin Chen ◽  
Yun-He Li ◽  
Jian Wen ◽  
Zhen Li ◽  
Bin-Sheng Yu ◽  
...  
Keyword(s):  
Intervertebral Disc ◽  
Degrees Of Freedom ◽  
Mechanical Stability ◽  
Biomechanical Testing ◽  
Bending Stiffness ◽  
Biomechanical Study ◽  
Torsional Stiffness ◽  
P Value ◽  
Lateral Bending ◽  
Flexion Extension

Study Design: A biomechanical study. Objectives: The purpose of this study was to investigate the effects of cruciform and square incisions of annulus fibrosus (AF) on the mechanical stability of bovine intervertebral disc (IVD) in multiple degrees of freedom. Methods: Eight bovine caudal IVD motion segments (bone-disc-bone) were obtained from the local abattoir. Cruciform and square incisions were made at the right side of the specimen’s annulus using a surgical scalpel. Biomechanical testing of three-dimensional 6 degrees of freedom was then performed on the bovine caudal motion segments using the mechanical testing and simulation (MTS) machine. Force, displacement, torque and angle were recorded synchronously by the MTS system. P value <.05 was considered statistically significant. Results: Cruciform and square incisions of the AF reduced both axial compressive and torsional stiffness of the IVD and were significantly lower than those of the intact specimens ( P < .01). Left-side axial torsional stiffness of the cruciform incision was significantly higher than a square incision ( P < .01). Neither incision methods impacted flexional-extensional stiffness or lateral-bending stiffness. Conclusions: The cruciform and square incisions of the AF obviously reduced axial compression and axial rotation, but they did not change the flexion-extension and lateral-bending stiffness of the bovine caudal IVD. This mechanical study will be meaningful for the development of new approaches to AF repair and the rehabilitation of the patients after receiving discectomy.

Adjacent-segment effects of lumbar cortical screw–rod fixation versus pedicle screw–rod fixation with and without interbody support

2021 ◽  
pp. 1-7
Author(s):  
Piyanat Wangsawatwong ◽  
Anna G. U. Sawa ◽  
Bernardo de Andrada Pereira ◽  
Jennifer N. Lehrman ◽  
Luke K. O’Neill ◽  
...  
Keyword(s):  
Pedicle Screw ◽  
Interbody Fusion ◽  
Lumbar Fusion ◽  
Statistical Significance ◽  
Adjacent Segment ◽  
Lumbar Interbody Fusion ◽  
Lateral Bending ◽  
Single Level ◽  
Cortical Screw ◽  
Flexion Extension

OBJECTIVE Cortical screw–rod (CSR) fixation has emerged as an alternative to the traditional pedicle screw–rod (PSR) fixation for posterior lumbar fixation. Previous studies have concluded that CSR provides the same stability in cadaveric specimens as PSR and is comparable in clinical outcomes. However, recent clinical studies reported a lower incidence of radiographic and symptomatic adjacent-segment degeneration with CSR. No biomechanical study to date has focused on how the adjacent-segment mobility of these two constructs compares. This study aimed to investigate adjacent-segment mobility of CSR and PSR fixation, with and without interbody support (lateral lumbar interbody fusion [LLIF] or transforaminal lumbar interbody fusion [TLIF]). METHODS A retroactive analysis was done using normalized range of motion (ROM) data at levels adjacent to single-level (L3–4) bilateral screw–rod fixation using pedicle or cortical screws, with and without LLIF or TLIF. Intact and instrumented specimens (n = 28, all L2–5) were tested using pure moment loads (7.5 Nm) in flexion, extension, lateral bending, and axial rotation. Adjacent-segment ROM data were normalized to intact ROM data. Statistical comparisons of adjacent-segment normalized ROM between two of the groups (PSR followed by PSR+TLIF [n = 7] and CSR followed by CSR+TLIF [n = 7]) were performed using 2-way ANOVA with replication. Statistical comparisons among four of the groups (PSR+TLIF [n = 7], PSR+LLIF [n = 7], CSR+TLIF [n = 7], and CSR+LLIF [n = 7]) were made using 2-way ANOVA without replication. Statistical significance was set at p < 0.05. RESULTS Proximal adjacent-segment normalized ROM was significantly larger with PSR than CSR during flexion-extension regardless of TLIF (p = 0.02), or with either TLIF or LLIF (p = 0.04). During lateral bending with TLIF, the distal adjacent-segment normalized ROM was significantly larger with PSR than CSR (p < 0.001). Moreover, regardless of the types of screw-rod fixations (CSR or PSR), TLIF had a significantly larger normalized ROM than LLIF in all directions at both proximal and distal adjacent segments (p ≤ 0.04). CONCLUSIONS The use of PSR versus CSR during single-level lumbar fusion can significantly affect mobility at the adjacent segment, regardless of the presence of TLIF or with either TLIF or LLIF. Moreover, the type of interbody support also had a significant effect on adjacent-segment mobility.

How the height and the area of the annulus fibrosus affect the range of motion behavior: A stochastic analysis

2018 ◽  
Vol 233 (10) ◽  
pp. 1985-1992
Author(s):  
Héctor E Jaramillo S
Keyword(s):  
Finite Element ◽  
Range Of Motion ◽  
Annulus Fibrosus ◽  
Element Model ◽  
Axial Rotation ◽  
Disc Height ◽  
Lateral Bending ◽  
Analytic Equation ◽  
Geometrical Properties ◽  
Flexion Extension

The annulus fibrosus has substantial variations in its geometrical properties (among individuals and between levels), and plays an important role in the biomechanics of the spine. Few works have studied the influence of the geometrical properties including annulus area, anterior / posterior disc height, and over the range of motion, but in general these properties have not been reported in the finite element models. This paper presents a probabilistic finite element analyses (Abaqus 6.14.2) intended to assess the effects of the average disc height ( hp) and the area ( A) of the annulus fibrosus on the biomechanics of the lumbar spine. The annulus model was loaded under flexion, extension, lateral bending, and axial rotation and analyzed for different combinations of hpand A in order to obtain their effects over the range of motion. A set of 50 combinations of hp(mean = 18.1 mm, SD = 3.5 mm) and A (mean = 49.8%, SD = 4.6%) were determined randomly according to a normal distribution. A Yeoh energy function was used for the matrix and an exponential function for the fibers. The range of motion was more sensitive to hpthan to A. With regard to the range of motion the segment was more sensitive in the following order: flexion, axial rotation, extension, and lateral bending. An increase of the hpproduces an increase of the range of motion, but this decreases when A increases. Comparing the range of motion with the experimental data, on average, 56.0% and 73.0% of the total of data were within the experimental range for the L4–L5 and L5–S1 segments, respectively. Further, an analytic equation was derived to obtain the range of motion as a function of the hpand A. This equation can be used to calibrate a finite element model of the spine segment, and also to understand the influence of each geometrical parameter on the range of motion.

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