Cartilage Thickness Distribution Affects Computational Model Predictions of Cervical Spine Facet Contact Parameters

2010 ◽  
Vol 133 (1) ◽  
Author(s):  
Wesley Womack ◽  
Ugur M. Ayturk ◽  
Christian M. Puttlitz
Keyword(s):  
Finite Element ◽  
Cervical Spine ◽  
Articular Cartilage ◽  
Cartilage Thickness ◽  
Implant Design ◽  
Lower Cervical Spine ◽  
Model Predictions ◽  
Geometric Representations ◽  
Spatially Varying ◽  
The Impact

With motion-sparing disk replacement implants gaining popularity as an alternative to anterior cervical discectomy and fusion (ACDF) for the treatment of certain spinal degenerative disorders, recent laboratory investigations have studied the effects of disk replacement and implant design on spinal kinematics and kinetics. Particularly relevant to cervical disk replacement implant design are any postoperative changes in solid stresses or contact conditions in the articular cartilage of the posterior facets, which are hypothesized to lead to adjacent-level degeneration. Such changes are commonly investigated using finite element methods, but significant simplification of the articular geometry is generally employed. The impact of such geometric representations has not been thoroughly investigated. In order to assess the effects of different models of cartilage geometry on load transfer and contact pressures in the lower cervical spine, a finite element model was generated using cadaver-based computed tomography imagery. Mesh resolution was varied in order to establish model convergence, and cadaveric testing was undertaken to validate model predictions. The validated model was altered to include four different geometric representations of the articular cartilage. Model predictions indicate that the two most common representations of articular cartilage geometry result in significant reductions in the predictive accuracy of the models. The two anatomically based geometric models exhibited less computational artifact, and relatively minor differences between them indicate that contact condition predictions of spatially varying thickness models are robust to anatomic variations in cartilage thickness and articular curvature. The results of this work indicate that finite element modeling efforts in the lower cervical spine should include anatomically based and spatially varying articular cartilage thickness models. Failure to do so may result in loss of fidelity of model predictions relevant to investigations of physiological import.

Using Force and Kinematic Driven Finite Element Models to Analyze Contact Pressure Distributions on the Tibial Plateau

2007 ◽  
Author(s):  
Kristen R. Hovinga ◽  
Jiang Yao ◽  
Amy L. Lerner
Keyword(s):  
Finite Element ◽  
Articular Cartilage ◽  
Soft Tissue ◽  
Mr Imaging ◽  
Load Distribution ◽  
Tibial Plateau ◽  
Fe Analysis ◽  
Implant Design ◽  
Finite Element Models ◽  
Pressure Distributions

Finite element (FE) models have become an effective tool in studying soft tissue behavior in the knee joint, including meniscal translation and deformation, as well as articular cartilage contact [1–2]. These models are also useful in osteoarthritis research and implant design [3–4]. Our group has previously used a kinematic-driven FE analysis to study the effect of weightbearing on the load distribution of tibio-menisco-femoral contact using MR imaging [5].

scholarly journals Finite Element Analysis and Comparative Study of 4 Kinds of Internal Fixation Systems for Anterior Cervical Discectomy and Fusion in Children

2021 ◽  
Author(s):  
ziyu li ◽  
Jianqiang Zhou ◽  
Zhijun Li ◽  
Shaojie Zhang ◽  
xing wang ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Cervical Spine ◽  
Finite Element Model ◽  
Internal Fixation ◽  
Element Model ◽  
Lower Cervical Spine ◽  
Element Analysis ◽  
Internal Fixation System ◽  
Fixation System

Abstract Background: Spinal injury in children usually occurs in the cervical spine region. Anterior fixation of lower cervical spine has been applied in the treatment of pediatric cervical spine injury and disease due to its stable and firm mechanical properties. This study performed finite element analysis and comparison of 4 different anterior cervical internal fixation systems for children, and explored more stable methods of anterior cervical internal fixation in children. Methods: A finite element model of 6-year-old children with lower cervical spine C4/5 discectomy was established, and the self-designed lower cervical spine anterior locking internal fixation system ACBLP and the children’s anterior cervical internal fixation system ACOP, ACVLP, ACSLP plate screws were fixed and loaded on the model. 27.42N•m torque load was applied to each internal fixation model under 6 working conditions of anteflexion, backward flexion, left flexion, right flexion, left rotation and right rotation, to simulate the movement of the cervical spine. The activity and stress distribution cloud diagram of each finite element model was obtained. Results: In the four internal fixation models of ACOP, ACVLP, ACSLP, and ACBLP, the mobility of C4/5 segment basically showed a decreasing relationship, and the mobility of adjacent segments increased significantly. In the Mises stress cloud diagram of the cervical spine of the four models, the vertebral body and accessories of the ACBLP model born the least stress, followed by ACSLP; The steel plate and screws in the ACVLP internal fixation model were the most stressed; The stress of the internal fixation system (plate/screw) in all models increased in the order of ACBLP, ACSLP, ACVLP, and ACOP.Conclusions: ACBLP internal fixation system had obvious advantages in anterior internal fixation of lower cervical spine in children, C4/5 had the smallest degree of movement, relative displacement was minimal, the stress on the pedicle was the least while the stress on the plate screw was relatively the smallest.

scholarly journals The impact of helicopter emergency medical services and craniocervical traction on the early reduction of cervical spine dislocation in a rural area of Japan

2020 ◽  
Author(s):  
Deokcheol Lee ◽  
Keisuke Kawano ◽  
Shotaro Ishida ◽  
Yoichiro Yamaguchi ◽  
Tomofumi Kuroki ◽  
...  
Keyword(s):  
Cervical Spine ◽  
Emergency Medical Services ◽  
Success Rate ◽  
Closed Reduction ◽  
Lower Cervical Spine ◽  
Helicopter Emergency Medical Services ◽  
Emergency Medical ◽  
Complete Paralysis ◽  
Group A ◽  
The Impact

Abstract Background Several clinical and basic studies have shown that an association exists between achieving decompression of the spinal cord within a few hours and neurological recovery, even in patients with complete paralysis due to cervical spine dislocation. This study aimed to clarify the impact of helicopter emergency medical services(HEMS)and craniocervical traction using a halo ring on rapid reduction of lower cervical spine dislocation in rural Japan. Methods The success rate of and factors inhibiting closed reduction, time from injury to reduction and functional prognosis of lower cervical spine dislocations treated between July 2012 and January 2020 were retrospectively analysed. Results Fourteen patients were transported by HEMS (group H), seven were by ambulances (group A) and two were by themselves. Although the average travelled distance and injury severity score were significantly higher in group H (64.5 km, 28.0) than in group A (24.7 km, 18.6), there was no significant difference in the average time to admission or the time to start craniocervical traction after admission between group H (159.4 min, 52.2 min) and group A (163.6 min, 53.2 min). The urgent traction could be administered for 20 patients. The success rate of closed reduction was 95%, and neurological deterioration following traction was not observed in any cases. The average traction time and weight for reduction were 30.3 min and 16.3 kg, respectively. Patients’ body size and fracture-dislocation types did not significantly affect the traction time or weight. The rate of reduction within 4 h after injury was higher in group H (79%) than in group A (33%). Herniated discs were found at dislocation levels in five patients by magnetic resonance imaging scans performed after closed reduction, and all cases of inner fixation were treated via the posterior approach an average of 5.7 days after admission. After these treatment, three of nine AIS A patients recovered the ability to walk, and all the three patients underwent successful closed reduction within 4 h after injury. Conclusion HEMS and highly successful closed reduction considerably contributed to the early reduction of cervical spine dislocation and can potentially improve complete paralysis.

Comparison of Stress Distribution in Surrounding Bone during Insertion of Dental Implants on Four Implant Threads under the Effect of an Impact: A Finite Element Study

2022 ◽  
Vol 54 ◽  
pp. 89-101
Author(s):  
Noureddine Djebbar ◽  
Abdessamed Bachiri ◽  
Benali Boutabout
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Load Transfer ◽  
Three Dimensional ◽  
Primary Stability ◽  
Implant Design ◽  
Element Analysis ◽  
Three Dimensional Finite Element ◽  
The Impact ◽  
Surrounding Bone

The design of an implant thread plays a fundamental role in the osseointegration process, particularly in low-density bone. It has been postulated that design features that maximize the surface area available for contact may improve mechanical anchorage and stability in cancellous bone. The primary stability of a dental implant is determined by the mechanical engagement between the implant and bone at the time of implant insertion. The contact area of implant-bone interfaces and the concentrated stresses on the marginal bones are principal concerns of implant designers. Numerous factors influence load transfer at the bone-implant interface, for example, the type of loading, surface structure, amount of surrounding bone, material properties of the implant and implant design. The purpose of this study was to investigate the effects of the impact two different projectile of implant threads on stress distribution in the jawbone using three-dimensional finite element analysis.

Intubation biomechanics: validation of a finite element model of cervical spine motion during endotracheal intubation in intact and injured conditions

2018 ◽  
Vol 28 (1) ◽  
pp. 10-22 ◽  
Author(s):  
Benjamin C. Gadomski ◽  
Snehal S. Shetye ◽  
Bradley J. Hindman ◽  
Franklin Dexter ◽  
Brandon G. Santoni ◽  
...  
Keyword(s):  
Spinal Cord ◽  
Finite Element ◽  
Cervical Spine ◽  
Endotracheal Intubation ◽  
Macintosh Laryngoscope ◽  
Element Model ◽  
Fe Model ◽  
Intervertebral Motion ◽  
Model Predictions ◽  
Spine Motion

OBJECTIVEBecause of limitations inherent to cadaver models of endotracheal intubation, the authors’ group developed a finite element (FE) model of the human cervical spine and spinal cord. Their aims were to 1) compare FE model predictions of intervertebral motion during intubation with intervertebral motion measured in patients with intact cervical spines and in cadavers with spine injuries at C-2 and C3–4 and 2) estimate spinal cord strains during intubation under these conditions.METHODSThe FE model was designed to replicate the properties of an intact (stable) spine in patients, C-2 injury (Type II odontoid fracture), and a severe C3–4 distractive-flexion injury from prior cadaver studies. The authors recorded the laryngoscope force values from 2 different laryngoscopes (Macintosh, high intubation force; Airtraq, low intubation force) used during the patient and cadaver intubation studies. FE-modeled motion was compared with experimentally measured motion, and corresponding cord strain values were calculated.RESULTSFE model predictions of intact intervertebral motions were comparable to motions measured in patients and in cadavers at occiput–C2. In intact subaxial segments, the FE model more closely predicted patient intervertebral motions than did cadavers. With C-2 injury, FE-predicted motions did not differ from cadaver measurements. With C3–4 injury, however, the FE model predicted greater motions than were measured in cadavers. FE model cord strains during intubation were greater for the Macintosh laryngoscope than the Airtraq laryngoscope but were comparable among the 3 conditions (intact, C-2 injury, and C3–4 injury).CONCLUSIONSThe FE model is comparable to patients and cadaver models in estimating occiput–C2 motion during intubation in both intact and injured conditions. The FE model may be superior to cadavers in predicting motions of subaxial segments in intact and injured conditions.

Finite Element Model of the Human Lower Cervical Spine: Parametric Analysis of the C4-C6 Unit

1997 ◽  
Vol 119 (1) ◽  
pp. 87-92 ◽  
Author(s):  
N. Yoganandan ◽  
S. Kumaresan ◽  
L. Voo ◽  
F. A. Pintar
Keyword(s):  
Finite Element ◽  
Cervical Spine ◽  
Finite Element Model ◽  
Compressive Stress ◽  
Vertebral Body ◽  
Element Model ◽  
Intervertebral Disk ◽  
Von Mises Stress ◽  
Lower Cervical Spine ◽  
Intervertebral Disks

In this study, a three-dimensional finite element model of the human lower cervical spine (C4-C6) was constructed. The mathematical model was based on close-up CT scans from a young human cadaver. Cortical shell, cancellous core, endplates, and posterior elements including the lateral masses, pedicle, lamina, and transverse and spinous processes, and the intervertebral disks, were simulated. Using the material properties from literature, the 10,371-element model was exercised under an axial compressive mode of loading. The finite element model response agreed with literature. As a logical step, a parametric study was conducted by evaluating the biomechanical response secondary to changes in the elastic moduli of the intervertebral disk and the endplates. In the stress analysis, the minimum principal compressive stress was used for the cancellous core of the vertebral body and von Mises stress was used for the endplate component. The model output indicated that an increase in the elastic modulii of the disk resulted in an increase in the endplate stresses at all the three spinal levels. In addition, the inferior endplate of the middle vertebral body responded with the highest mean compressive stress followed by its superior counterpart. Furthermore, the middle vertebral body produced the highest compressive stresses compared to its counterparts. These findings appear to correlate with experimental results as well as common clinical experience wherein cervical fractures are induced due to external compressive forces. As a first step, this model will lead to more advanced simulations as additional data become available.

Validation of a Finite Element Model of the Young Normal Lower Cervical Spine

2008 ◽  
Vol 36 (9) ◽  
pp. 1458-1469 ◽  
Author(s):  
John A. Wheeldon ◽  
Brian D. Stemper ◽  
Narayan Yoganandan ◽  
Frank A. Pintar
Keyword(s):  
Finite Element ◽  
Cervical Spine ◽  
Finite Element Model ◽  
Element Model ◽  
Lower Cervical Spine
Sign in / Sign up

Export Citation Format

Share Document