scholarly journals Biomechanical Analysis of Posterior Ligaments of Cervical Spine and Laminoplasty

2021 ◽  
Vol 11 (16) ◽  
pp. 7645
Author(s):  
Norihiro Nishida ◽  
Muzammil Mumtaz ◽  
Sudharshan Tripathi ◽  
Amey Kelkar ◽  
Takashi Sakai ◽  
...  
Keyword(s):  
Cervical Spine ◽  
Element Model ◽  
Axial Rotation ◽  
Vital Role ◽  
Contact Forces ◽  
Biomechanical Analysis ◽  
Cervical Laminoplasty ◽  
Physiological Loading ◽  
Flexion Extension ◽  
Valuable Procedure

Cervical laminoplasty is a valuable procedure for myelopathy but it is associated with complications such as increased kyphosis. The effect of ligament damage during cervical laminoplasty on biomechanics is not well understood. We developed the C2–C7 cervical spine finite element model and simulated C3–C6 double-door laminoplasty. Three models were created (a) intact, (b) laminoplasty-pre (model assuming that the ligamentum flavum (LF) between C3–C6 was preserved during surgery), and (c) laminoplasty-res (model assuming that the LF between C3–C6 was resected during surgery). The models were subjected to physiological loading, and the range of motion (ROM), intervertebral nucleus stress, and facet contact forces were analyzed under flexion/extension, lateral bending, and axial rotation. The maximum change in ROM was observed under flexion motion. Under flexion, ROM in the laminoplasty-pre model increased by 100.2%, 111.8%, and 98.6% compared to the intact model at C3–C4, C4–C5, and C5–C6, respectively. The ROM in laminoplasty-res further increased by 105.2%, 116.8%, and 101.8% compared to the intact model at C3–C4, C4–C5, and C5–C6, respectively. The maximum stress in the annulus/nucleus was observed under left bending at the C4–C5 segment where an increase of 139.5% and 229.6% compared to the intact model was observed for laminoplasty-pre and laminoplasty-res model, respectively. The highest facet contact forces were observed at C4–C5 under axial rotation, where an increase of 500.7% and 500.7% was observed compared to the intact model for laminoplasty-pre and laminoplasty-res, respectively. The posterior ligaments of the cervical spine play a vital role in restoring/stabilizing the cervical spine. When laminoplasty is performed, the surgeon needs to be careful not to injure the posterior soft tissue, including ligaments such as LF.

scholarly journals Biomechanical Analysis of Allograft Spacer Failure as a Function of Cortical-Cancellous Ratio in Anterior Cervical Discectomy/Fusion: Allograft Spacer Alone Model

2020 ◽  
Vol 10 (18) ◽  
pp. 6413
Author(s):  
Ji-Won Kwon ◽  
Hwan-Mo Lee ◽  
Tae-Hyun Park ◽  
Sung Jae Lee ◽  
Young-Woo Kwon ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Element Model ◽  
Axial Rotation ◽  
Biomechanical Analysis ◽  
Flexion Extension ◽  
Hybrid Motion ◽  
Anterior Cervical Discectomy Fusion ◽  
Flexion And Extension ◽  
Additional Fixation ◽  
Lateral Walls

The design and ratio of the cortico-cancellous composition of allograft spacers are associated with graft-related problems, including subsidence and allograft spacer failure. Methods: The study analyzed stress distribution and risk of subsidence according to three types (cortical only, cortical cancellous, cortical lateral walls with a cancellous center bone) and three lengths (11, 12, 14 mm) of allograft spacers under the condition of hybrid motion control, including flexion, extension, axial rotation, and lateral bending,. A detailed finite element model of a previously validated, three-dimensional, intact C3–7 segment, with C5–6 segmental fusion using allograft spacers without fixation, was used in the present study. Findings: Among the three types of cervical allograft spacers evaluated, cortical lateral walls with a cancellous center bone exhibited the highest stress on the cortical bone of spacers, as well as the endplate around the posterior margin of the spacers. The likelihood of allograft spacer failure was highest for 14 mm spacers composed of cortical lateral walls with a cancellous center bone upon flexion (PVMS, 270.0 MPa; 250.2%) and extension (PVMS: 371.40 MPa, 344.2%). The likelihood of allograft spacer subsidence was also highest for the same spacers upon flexion (PVMS, 4.58 MPa; 28.1%) and extension (PVMS: 12.71 MPa, 78.0%). Conclusion: Cervical spacers with a smaller cortical component and of longer length can be risk factors for allograft spacer failure and subsidence, especially in flexion and extension. However, further study of additional fixation methods, such as anterior plates/screws and posterior screws, in an actual clinical setting is necessary.

scholarly journals Biomechanical analysis of a newly developed interspinous process device conjunction with interbody cage based on a finite element model

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0243771
Author(s):  
In-Suk Bae ◽  
Koang-Hum Bak ◽  
Hyoung-Joon Chun ◽  
Je Il Ryu ◽  
Sung-Jae Park ◽  
...  
Keyword(s):  
Finite Element ◽  
Lumbar Spine ◽  
Finite Element Model ◽  
Element Model ◽  
Axial Rotation ◽  
Biomechanical Analysis ◽  
Interbody Cage ◽  
Lateral Bending ◽  
Flexion Extension ◽  
Interspinous Process Device

Purpose This study aimed to investigate the biomechanical effects of a newly developed interspinous process device (IPD), called TAU. This device was compared with another IPD (SPIRE) and the pedicle screw fixation (PSF) technique at the surgical and adjacent levels of the lumbar spine. Materials and methods A three-dimensional finite element model analysis of the L1-S1 segments was performed to assess the biomechanical effects of the proposed IPD combined with an interbody cage. Three surgical models—two IPD models (TAU and SPIRE) and one PSF model—were developed. The biomechanical effects, such as range of motion (ROM), intradiscal pressure (IDP), disc stress, and facet loads during extension were analyzed at surgical (L3-L4) and adjacent levels (L2-L3 and L4-L5). The study analyzed biomechanical parameters assuming that the implants were perfectly fused with the lumbar spine. Results The TAU model resulted in a 45%, 49%, 65%, and 51% decrease in the ROM at the surgical level in flexion, extension, lateral bending, and axial rotation, respectively, when compared to the intact model. Compared to the SPIRE model, TAU demonstrated advantages in stabilizing the surgical level, in all directions. In addition, the TAU model increased IDP at the L2-L3 and L4-L5 levels by 118.0% and 78.5% in flexion, 92.6% and 65.5% in extension, 84.4% and 82.3% in lateral bending, and 125.8% and 218.8% in axial rotation, respectively. Further, the TAU model exhibited less compensation at adjacent levels than the PSF model in terms of ROM, IDP, disc stress, and facet loads, which may lower the incidence of the adjacent segment disease (ASD). Conclusion The TAU model demonstrated more stabilization at the surgical level than SPIRE but less stabilization than the PSF model. Further, the TAU model demonstrated less compensation at adjacent levels than the PSF model, which may lower the incidence of ASD in the long term. The TAU device can be used as an alternative system for treating degenerative lumbar disease while maintaining the physiological properties of the lumbar spine and minimizing the degeneration of adjacent segments.

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.

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.

scholarly journals Biomechanical Analysis of an Anterior Cervical Discectomy and Fusion Pseudarthrosis Model Revised With Machined Interfacet Allograft Spacers

2019 ◽  
Vol 10 (8) ◽  
pp. 973-981
Author(s):  
Raymond J. Hah ◽  
Ram Alluri ◽  
Paul A. Anderson
Keyword(s):  
Range Of Motion ◽  
Study Design ◽  
Axial Rotation ◽  
Biomechanical Analysis ◽  
Anterior Cervical Discectomy ◽  
Lateral Bending ◽  
Cervical Discectomy ◽  
Single Level ◽  
Flexion Extension ◽  
Potential Applications

Study Design: Biomechanics study. Objectives: To evaluate the biomechanical advantage of interfacet allograft spacers in an unstable single-level and 2-level anterior cervical discectomy and fusion (ACDF) pseudoarthrosis model. Methods: Nine single-level and 8 two-level ACDF constructs were tested. Range of motion in flexion-extension (FE), lateral bending (LB), and axial rotation (AR) at 1.5 N m were collected in 4 testing configurations: (1) intact spine, (2) ACDF with interbody graft and plate/screw, (3) ACDF with interbody graft and plate/loosened screws (loose condition), and (4) ACDF with interbody graft and plate/loosened screws supplemented with interfacet allograft spacers (rescue condition). Results: All fixation configurations resulted in statistically significant decreases in range of motion in all bending planes compared with the intact spine ( P < .05). One Level. Performing ACDF with interbody graft and plate on the intact spine reduced FE, LB, and AR 60.0%, 64.9%, and 72.9%, respectively. Loosening the ACDF screws decreased these reductions to 40.9%, 44.6%, and 52.1%. The addition of interfacet allograft spacers to the loose condition increased these reductions to 74.0%, 84.1%, and 82.1%. Two Level. Performing ACDF with interbody graft and plate on the intact spine reduced FE, LB, and AR 72.0%, 71.1%, and 71.2%, respectively. Loosening the ACDF screws decreased these reductions to 55.4%, 55.3%, and 51.3%. The addition of interfacet allograft spacers to the loose condition significantly increased these reductions to 82.6%, 91.2%, and 89.3% ( P < .05). Conclusions: Supplementation of a loose ACDF construct (pseudarthrosis model) with interfacet allograft spacers significantly increases stability and has potential applications in treating cervical pseudarthrosis.

scholarly journals A Biomechanical Analysis of Ankle Instability in Supination External Rotation Ankle Fractures

2018 ◽  
Vol 3 (3) ◽  
pp. 2473011418S0006
Author(s):  
Eric Hempen ◽  
Bennet Butler ◽  
Muturi Muriuki ◽  
Anish Kadakia
Keyword(s):  
Ankle Instability ◽  
External Rotation ◽  
Axial Rotation ◽  
Injury Pattern ◽  
Contact Forces ◽  
Biomechanical Analysis ◽  
Ankle Injuries ◽  
Injury Patterns ◽  
Supination External Rotation ◽  
Rotation Stress

Category: Trauma Introduction/Purpose: Supination external rotation (SER) 2 and SER3 ankle injuries are thought to be stable whereas SER4 injuries are thought to be unstable. In other words, deltoid rupture is thought to be a necessary component of instability in SER injuries. However, biomechanical evidence has shown that as little as 1 mm talar shift results in 40% loss in contact area leading to increased contact forces. Additionally, the external rotation stress exam which is the typical test used to detect instability is poorly standardized in the literature limiting its ability to detect subtle instability. Therefore the purpose of this study is to analyze talar rotation and translation with external rotation stress specifically in SER2 and SER3 patterns in an effort to better define which injury patterns are unstable. Methods: 19 legs disarticulated below the knee were obtained. Optotrak optoelectronic 3D motion measurement system was used to determine positioning of the talus compared to the tibia. Specimens were first tested intact using a jig capable of exerting known axial and rotational forces through the hindfoot in line with the weightbearing axis of the tibia. Specimens were loaded with 150N to simulate physiologic load and sequentially stressed with 0, 1, 2, 3, and 4Nm of external rotation. SER2 injury was then created by creating a Weber B distal fibula fracture and AITFL rupture. The above testing was then repeated. Next the injury was converted to SER3 by rupturing the PITFL, and the above testing was repeated. In all conditions coronal and sagittal translation as well as axial and coronal angulation from the uninjured/unstressed state were recorded. The SER2 and SER3 conditions were compared to the intact condition using a paired t-test. Results: When compared to the uninjured state, the SER2 injury pattern demonstrated statistically significant differences in the following parameters: - axial rotation at 1Nm (11.0±4.2°, p<0.0005), 2Nm (12.8±4.4°, p<0.0005), 3Nm (14.4±4.9°, p<0.0005), and 4Nm (15.8±5.2°, p<0.0005) - sagittal translation at 1Nm (5.2±3.6 mm, p=0.007), and 2Nm (6.4±3.9 mm, p=0.02) - coronal translation at 3Nm(0.6±3.2 mm, p=0.004), and 4Nm (0.7±3.5 mm, p=0.003) When compared to the uninjured state, the SER3 injury pattern demonstrated statistically significant differences in the following parameters: - coronal rotation at 4Nm (-0.9±6.8°, p=0.03) - axial rotation at 1Nm (12.3±4.4°, p<0.0005), 2Nm (16.0±4.7°, p<0.0005), 3Nm (18.2±5.1°, p<0.0005), and 4Nm (20.4±5.7°, p<0.0005) - sagittal translation at 1Nm (5.0±3.9 mm, p=0.03), and 2Nm (6.4±3.9 mm, p=0.01) - coronal translation at 1Nm (0.7±1.9 mm, p=0.05), 2Nm (0.8±2.5 mm, p=0.01), 3Nm (1.1±3.0 mm, p<0.0005), and 4Nm (1.5±3.6 mm, p<0.0005) Conclusion: Current literature describes ankle instability in SER injury patterns in terms of coronal translation, and suggests that SER2 and SER3 injury patterns are stable. However, our data demonstrates that even SER2 and SER3 injury patterns with an intact deltoid ligament show signs of instability in sagittal translation and axial rotation as well as subtle signs of instability in coronal translation, especially at higher torques. As previously stated, subtle instability has been shown to significantly decrease contact forces, and therefore this data supports further study of long term clinical outcomes and reconsideration of our treatment algorithms for SER2 and SER3 fractures.

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

scholarly journals Comparison of the efficacy of three cervical collars in restricting cervical range of motion: A randomized study

2018 ◽  
Vol 27 (1) ◽  
pp. 24-29 ◽  
Author(s):  
Jae Guk Kim ◽  
Sung Hwan Bang ◽  
Gu Hyun Kang ◽  
Yong Soo Jang ◽  
Wonhee Kim ◽  
...  
Keyword(s):  
Cervical Spine ◽  
Range Of Motion ◽  
Cervical Spine Injury ◽  
Axial Rotation ◽  
The Other ◽  
Spine Injury ◽  
Cervical Range Of Motion ◽  
Flexion Extension ◽  
Cervical Immobilization ◽  
The Difference

Background: The cervical collar has been used as a common device for the initial stabilization of the cervical spine. Although many cervical collars are commercially available, there is no consensus on which offers the greatest protection, with studies showing considerable variations in their ability to restrict cervical range of motion. The use of the XCollar (Emegear, Carpinteria, CA) has been known to decrease the risk of spinal cord injury by minimizing potential cervical spinal distraction. We compared XCollar with two other cervical collars commonly used for adult patients with cervical spine injury to evaluate the difference in effectiveness between the three cervical collars to restrict cervical range of motion. Objectives: This study aimed to evaluate the difference between the three cervical collars in their ability to restrict cervical range of motion. Method: A total of 30 healthy university students aged 21–25 years participated in this study. Participants with any cervical disease and symptoms were excluded. Three cervical collars were tested: Philadelphia® Collar, Stifneck® Select™ Collar, and XCollar. A digital camera and an image-analysis technique were used to evaluate cervical range of motion during flexion, extension, bilateral bending and bilateral axial rotation. Cervical range of motion was evaluated in both the unbraced and braced condition. Results: XCollar permitted less than a mean of 10° of movement during flexion, extension, bilateral bending and bilateral axial rotation. This was less than the movement permitted by the other two cervical collars. Conclusion: XCollar presented superior cervical immobilization compared to the other two commonly used cervical collars in this study. Thus, when cervical collar is considered for an adult patient with cervical spine injury, XCollar might be one of the considerate options as a cervical immobilization device.

Biomechanical analysis of Goel technique for C1–2 fusion

2011 ◽  
Vol 14 (5) ◽  
pp. 639-646 ◽  
Author(s):  
Jon Park ◽  
Justin K. Scheer ◽  
T. Jesse Lim ◽  
Vedat Deviren ◽  
Christopher P. Ames
Keyword(s):  
Motion Tracking ◽  
Tracking System ◽  
Testing Machine ◽  
Pedicle Screws ◽  
Axial Rotation ◽  
Biomechanical Analysis ◽  
Lateral Bending ◽  
Flexion Extension ◽  
Rod System ◽  
Harms Technique

Object The Goel technique, in which C1–2 intraarticular spacers are used, may be performed to restore stability to a disrupted atlantoaxial complex in conjunction with the Harms technique of placing polyaxial screws and bilateral rods. However, it has yet to be determined biomechanically whether the addition of the C1–2 joint spacers increases the multiaxial rigidity of the fixation construct. The goal of this study was to quantify changes in multiaxial rigidity of the combined Goel-Harms technique with the addition of C1–2 intraarticular spacers. Methods Seven cadaveric cervical spines (occiput–C2) were submitted to nondestructive flexion-extension, lateral bending, and axial rotation tests in a material testing machine spine tester. The authors applied 1.5 Nm at a rate of 0.1 Nm/second and held it constant for 10 seconds. The specimens were loaded 3 times, and data were collected on the third cycle. Testing of the specimens was performed for the following groups: 1) intact (I); 2) with the addition of C-1 lateral mass/C-2 pedicle screws and rod system (I+SR); 3) with C1–2 joint capsule incision, decortication (2 mm on top and bottom of each joint [that is, the C-1 and C-2 surface) and addition of bilateral C1–2 intraarticular spacers at C1–2 junction to the screws and rods (I+SR+C); 4) after removal of the posterior rods and only the bilateral spacers in place (I+C); 5) after removal of spacers and further destabilization with simulated odontoidectomy for a completely destabilized case (D); 6) with addition of posterior rods to the destabilized case (D+SR); and 7) with addition of bilateral C1–2 intraarticular spacers at C1–2 junction to the destabilized case (D+SR+C). The motion of C-1 was measured by a 3D motion tracking system and the motion of C-2 was measured by the rotational sensor of the testing system. The range of motion (ROM) and neutral zone (NZ) across C-1 and C-2 were evaluated. Results For the intact spine test groups, the addition of screws/rods (I+SR) and screws/rods/cages (I+SR+C) significantly reduced ROM and NZ compared with the intact spine (I) for flexion-extension and axial rotation (p < 0.05) but not lateral bending (p > 0.05). The 2 groups were not significantly different from each other in any bending mode for ROM and NZ, but in the destabilized condition the addition of screws/rods (D+SR) and screws/rods/cages (D+SR+C) significantly reduced ROM and NZ compared with the destabilized spine (D) in all bending modes (p < 0.05). Furthermore, the addition of the C1–2 intraarticular spacers (D+SR+C) significantly reduced ROM (flexion-extension and axial rotation) and NZ (lateral bending) compared with the screws and rods alone (D+SR). Conclusions Study result indicated that both the Goel and Harms techniques alone and with the addition of the C1–2 intraarticular spacers to the Goel-Harms technique are advantageous for stabilizing the atlantoaxial segment. The Goel technique combined with placement of a screw/rod construct appears to result in additional construct rigidity beyond the screw/rod technique and appears to be more useful in very unstable cases.

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