Toward Patient-Specific Cervical Spine Functional Spinal Unit FE Modeling and Validation

2008 ◽  
Author(s):  
Nicole A. Kallemeyn ◽  
Srinivas C. Tadepalli ◽  
Kiran H. Shivanna ◽  
Nicole M. Grosland
Keyword(s):  
Cervical Spine ◽  
Sagittal Plane ◽  
Treatment Modalities ◽  
Patient Specific ◽  
Fe Model ◽  
Altered States ◽  
Fe Modeling ◽  
Functional Spinal Unit ◽  
Development Methods ◽  
Mesh Development

Preventive measures and treatment modalities for correcting spinal disorders benefit significantly from advancements aimed at understanding the biomechanics of the human spine in the normal as well as altered states [1]. Finite element (FE) modeling is a useful tool to understand the behavior of the cervical spine under such conditions. In order for an FE model to yield clinically relevant results, the geometry must be as realistic as possible [2], in addition to incorporating accurate material properties and boundary conditions. The spine’s anatomy is very complex, rendering it difficult to acquire accurate geometrical representations for FE analysis. Many meshes in the literature are based on simplified or idealized geometries, or are assumed to be symmetric about the sagittal plane [3]. Traditional meshing techniques are time consuming and tedious, and lack remeshing capabilities [2]. The ability to create hexahedral cervical spine FE models on a patient-specific basis is a desirable task because it can account for variations in anatomy, as well as provide insight for surgical planning/treatment. Our mesh development methods improve on existing multi-block meshing methods to make this possible. We have created a C45 functional spinal unit (FSU) using these techniques, and to date have validated it by comparison to data presented in the literature.

BIOMECHANICAL EFFECT OF THORACIC POSTERIOR VERTEBRAL ELEMENTS ON PATTERNS OF THE LOCI OF INSTANTANEOUS AXES OF ROTATION IN SAGITTAL PLANE

2003 ◽  
Vol 07 (03n04) ◽  
pp. 191-200 ◽  
Author(s):  
Ee-Chon Teo ◽  
Tian-Xia Qiu ◽  
Kai Yang ◽  
Hong-Wan Ng ◽  
Kim-Kheng Lee
Keyword(s):  
Finite Element ◽  
Sagittal Plane ◽  
Relevant Information ◽  
Spinal Instability ◽  
Fe Model ◽  
Spinal Stability ◽  
Fe Method ◽  
Functional Spinal Unit ◽  
Biomechanical Effect ◽  
Flexion And Extension

The objective of this study was to investigate the effect of the thoracic posterior vertebral elements on the kinematics of T10–T11 motion segment in sagittal plane by assessing the locations and loci of the instantaneous axes of rotation (IARs) under flexion and extension pure moments using finite element (FE) method. The IAR has proven to be a useful parameter of vertebral motion and it is an indicator of spinal instability. An anatomically accurate FE model of thoracic T10–T11 functional spinal unit (FSU) was used to characterize the loci of centers of rotation for the intact T10–T11 FSU and disc body unit (without posterior vertebral elements) under flexion and extension pure moments. The centers of rotation predicted by the intact model and disc body unit of thoracic T10–T11 for both flexion and extension were directly below the geometrical center of the moving vertebra. However, the loci of the IARs were significantly affected by the posterior vertebral elements. The loci of instantaneous axes of rotation for the intact model were tracked superoanteriorly and inferoposteriorly for flexion and extension with rotation, respectively. While, for the disc body unit, the loci were detected to diverge lateroinferiorly from the mid-height of the intervertebral disc, they converge medio-inferiorly toward the superior endplate of the inferior vertebra T11 with increased moment. These findings may offer an insight to better understanding the kinematics of the human thoracic spine and provide clinically relevant information for the evaluation of spinal stability and implant devices functionality.

The influence of seat back rake on ligament loadings in rear-end impact

2005 ◽  
Vol 219 (2) ◽  
pp. 197-205 ◽  
Author(s):  
W Z Golinski ◽  
R Gentle
Keyword(s):  
Finite Element ◽  
Cervical Spine ◽  
Sagittal Plane ◽  
Head Rotation ◽  
Ligament Injury ◽  
Fe Model ◽  
Rotational Stiffness

A biomechanical finite element (FE) model of the 50th percentile male human cervical spine, capable of predicting ligament loadings in whiplash scenarios, has been developed and previously reported. The study reported here analyses the influence of seat back rake on ligament injury in two scenarios: firstly, the in position, where the car occupant is looking forward and the head remains in the sagittal plane, and, secondly, the out of position, where the car occupant is initially looking slightly to one side. In both cases the results show an increase in ligament loading with a decrease of seat back rotational stiffness, substantiating the need for dynamic seat testing. Moreover, comparing individual ligament loading data shows that the initial head rotation scenario is more damaging to the cervical spine than the sagittal plane scenario, confirming a published hypothesis.

scholarly journals Evolution of knowledge on meniscal biomechanics: a 40 year perspective

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Amin Mohamadi ◽  
Kaveh Momenzadeh ◽  
Aidin Masoudi ◽  
Kempland C. Walley ◽  
Kenny Ierardi ◽  
...  
Keyword(s):  
Future Research ◽  
Fe Model ◽  
Cruciate Ligaments ◽  
Fe Modeling ◽  
Meniscal Tears ◽  
Medical Subject Headings ◽  
Model Studies ◽  
The Past ◽  
Mesh Terms ◽  
Kinematic Studies

Abstract Background Knowledge regarding the biomechanics of the meniscus has grown exponentially throughout the last four decades. Numerous studies have helped develop this knowledge, but these studies have varied widely in their approach to analyzing the meniscus. As one of the subcategories of mechanical phenomena Medical Subject Headings (MeSH) terms, mechanical stress was introduced in 1973. This study aims to provide an up-to-date chronological overview and highlights the evolutionary comprehension and understanding of meniscus biomechanics over the past forty years. Methods A literature review was conducted in April 2021 through PubMed. As a result, fifty-seven papers were chosen for this narrative review and divided into categories; Cadaveric, Finite element (FE) modeling, and Kinematic studies. Results Investigations in the 1970s and 1980s focused primarily on cadaveric biomechanics. These studies have generated the fundamental knowledge basis for the emergence of FE model studies in the 1990s. As FE model studies started to show comparable results to the gold standard cadaveric models in the 2000s, the need for understanding changes in tissue stress during various movements triggered the start of cadaveric and FE model studies on kinematics. Conclusion This study focuses on a chronological examination of studies on meniscus biomechanics in order to introduce concepts, theories, methods, and developments achieved over the past 40 years and also to identify the likely direction for future research. The biomechanics of intact meniscus and various types of meniscal tears has been broadly studied. Nevertheless, the biomechanics of meniscal tears, meniscectomy, or repairs in the knee with other concurrent problems such as torn cruciate ligaments or genu-valgum or genu-varum have not been extensively studied.

scholarly journals Interventional Oncology Approach to Hepatic Metastases

2020 ◽  
Vol 37 (05) ◽  
pp. 484-491
Author(s):  
Cathal O'Leary ◽  
Michael C. Soulen ◽  
Susan Shamimi-Noori
Keyword(s):  
Liver Disease ◽  
Liver Function ◽  
Interventional Oncology ◽  
Hepatic Metastases ◽  
Locoregional Therapy ◽  
Treatment Modalities ◽  
Patient Specific ◽  
Curative Intent ◽  
Locoregional Therapies ◽  
Metastatic Liver

AbstractMetastatic liver disease is one of the major causes of cancer-related morbidity and mortality. Locoregional therapies offered by interventional oncologists alleviate cancer-related morbidity and in some cases improve survival. Locoregional therapies are often palliative in nature but occasionally can be used with curative intent. This review will discuss important factors to consider prior to palliative and curative intent treatment of metastatic liver disease with locoregional therapy. These factors include those specific to the tumor, liver function, liver reserve, differences between treatment modalities, and patient-specific considerations.

Design, Fabrication, and Accuracy of a Novel Noncovering Lock-Mechanism Bilateral Patient-Specific Drill Guide Template for Nondeformed and Deformed Thoracic Spines

2021 ◽  
pp. 155633162199633
Author(s):  
Mehran Ashouri-Sanjani ◽  
Shima Mohammadi-Moghadam ◽  
Parisa Azimi ◽  
Navid Arjmand
Keyword(s):  
Thoracic Spine ◽  
Sagittal Plane ◽  
Ct Scanning ◽  
Entry Point ◽  
In Vivo Studies ◽  
Patient Specific ◽  
Plane Angle ◽  
Severe Scoliosis ◽  
3D Printed

Background: Pedicle screw (PS) placement has been widely used in fusion surgeries on the thoracic spine. Achieving cost-effective yet accurate placements through nonradiation techniques remains challenging. Questions/Purposes: Novel noncovering lock-mechanism bilateral vertebra-specific drill guides for PS placement were designed/fabricated, and their accuracy for both nondeformed and deformed thoracic spines was tested. Methods: One nondeformed and 1 severe scoliosis human thoracic spine underwent computed tomographic (CT) scanning, and 2 identical proportions of each were 3-dimensional (3D) printed. Pedicle-specific optimal (no perforation) drilling trajectories were determined on the CT images based on the entry point/orientation/diameter/length of each PS. Vertebra-specific templates were designed and 3D printed, assuring minimal yet firm contacts with the vertebrae through a noncovering lock mechanism. One model of each patient was drilled using the freehand and one using the template guides (96 pedicle drillings). Postoperative CT scans from the models with the inserted PSs were obtained and superimposed on the preoperative planned models to evaluate deviations of the PSs. Results: All templates fitted their corresponding vertebra during the simulated operations. As compared with the freehand approach, PS placement deviations from their preplanned positions were significantly reduced: for the nonscoliosis model, from 2.4 to 0.9 mm for the entry point, 5.0° to 3.3° for the transverse plane angle, 7.1° to 2.2° for the sagittal plane angle, and 8.5° to 4.1° for the 3D angle, improving the success rate from 71.7% to 93.5%. Conclusions: These guides are valuable, as the accurate PS trajectory could be customized preoperatively to match the patients’ unique anatomy. In vivo studies will be required to validate this approach.

scholarly journals Revision surgery for incomplete resection or recurrence of cervical spine chordoma: a consecutive case series of 24 patients

2021 ◽  
Author(s):  
Peter Obid ◽  
Tamás Fekete ◽  
Philipp Drees ◽  
Daniel Haschtmann ◽  
Frank Kleinstück ◽  
...  
Keyword(s):  
Overall Survival ◽  
Cervical Spine ◽  
Survival Rate ◽  
Local Recurrence ◽  
Proton Beam ◽  
Revision Surgery ◽  
Patient Specific ◽  
Incomplete Resection ◽  
Pharyngeal Wall ◽  
Proton Beam Radiotherapy

Abstract Purpose Chordomas are rare tumors with an annual incidence of approximately one per million. Chordomas rarely metastasize but show a high local recurrence rate. Therefore, these patients present a major clinical challenge, and there is a paucity of the literature regarding the outcome after revision surgery of cervical spine chordomas. Available studies suggest a significantly worse outcome in revision scenarios. The purpose of this study is to analyze the survival rate, and complications of patients that underwent revision surgery for local recurrence or incomplete resection of chordoma at the craniocervical junction or at the cervical spine. Methods 24 consecutive patients that underwent revision surgery for cervical spine chordoma remnants or recurrence at a single center were reviewed retrospectively. We analyzed patient-specific surgical treatment strategies, complications, and outcome. Kaplan–Meier estimator was used to analyze five-year overall survival. Results Gross total resection was achieved in 17 cases. Seven patients developed dehiscence of the pharyngeal wall, being the most common long-term complication. No instability was observed. Postoperatively, four patients received proton beam radiotherapy and 12 patients had combined photon and proton beam radiotherapy. The five-year overall survival rate was 72.6%. Conclusion With thorough preoperative planning, appropriate surgical techniques, and the addition of adjuvant radiotherapy, results similar to those in primary surgery can be achieved.

Multidirection Validation of a Finite Element 50th Percentile Male Hybrid III Anthropomorphic Test Device for Spaceflight Applications

2019 ◽  
Vol 141 (3) ◽  
Author(s):  
Derek A. Jones ◽  
James P. Gaewsky ◽  
Mona Saffarzadeh ◽  
Jacob B. Putnam ◽  
Ashley A. Weaver ◽  
...  
Keyword(s):  
Finite Element ◽  
Injury Risk ◽  
Fe Model ◽  
Fe Modeling ◽  
Test Device ◽  
Qualitative And Quantitative ◽  
Hybrid Iii ◽  
Physical Tests ◽  
Quantitative Results ◽  
Male Hybrid

The use of anthropomorphic test devices (ATDs) for calculating injury risk of occupants in spaceflight scenarios is crucial for ensuring the safety of crewmembers. Finite element (FE) modeling of ATDs reduces cost and time in the design process. The objective of this study was to validate a Hybrid III ATD FE model using a multidirection test matrix for future spaceflight configurations. Twenty-five Hybrid III physical tests were simulated using a 50th percentile male Hybrid III FE model. The sled acceleration pulses were approximately half-sine shaped, and can be described as a combination of peak acceleration and time to reach peak (rise time). The range of peak accelerations was 10–20 G, and the rise times were 30–110 ms. Test directions were frontal (−GX), rear (GX), vertical (GZ), and lateral (GY). Simulation responses were compared to physical tests using the correlation and analysis (CORA) method. Correlations were very good to excellent and the order of best average response by direction was −GX (0.916±0.054), GZ (0.841±0.117), GX (0.792±0.145), and finally GY (0.775±0.078). Qualitative and quantitative results demonstrated the model replicated the physical ATD well and can be used for future spaceflight configuration modeling and simulation.

scholarly journals Frisbee - the first artificial cervical disc of 3RD generation

2014 ◽  
Vol 13 (1) ◽  
pp. 43-48
Author(s):  
Karin Büttner-Janz ◽  
Bernhard Meyer ◽  
Rafael Donatus Sambale ◽  
Hans-Joachim Wilke ◽  
Nelli Rüdiger ◽  
...  
Keyword(s):  
Heterotopic Ossification ◽  
Clinical Application ◽  
Wear Debris ◽  
Facet Joint ◽  
Sagittal Plane ◽  
Joint Surface ◽  
Cervical Disc ◽  
Cervical Disc Arthroplasty ◽  
Fe Model ◽  
Sliding Surface

OBJECTIVE: The current cervical disc arthroplasty is limited by postoperative facet joint arthritis, heterotopic ossification and segmental kyphosis. The total Frisbee disc, which has an upper convex/concave non-spherical surface and a lower flat sliding surface, is a new approach for improved outcomes. Prior to clinical application, safety and suitability tests are required. METHODS: The Frisbee is the first 3rd generation disc according to a new classification of total disc because it can precisely mimic the segmental ROM, including the soft limitation of axial rotation. The ISO 18192-1 test was carried out to determine the rate of wear debris. A FE model was used to assess the safety of prosthetic components. In the sagittal plane several variables to determine the most favorable lordotic angle were evaluated. RESULTS: Two angled prosthetic plates are safer than one sliding angled core to prevent the displacement. The lordosis of 7° of the Frisbee leads to kyphosis of no more than 2° without reduction of the ROM. The wear rate of the Frisbee is five times smaller compared to an FDA-approved disc with a spherical sliding surface. CONCLUSIONS: Based on the test results, the clinical application of Frisbee can now be studied. The postoperative kyphosis observed with other devices is not an issue with the Frisbee design. Physiological ROM is combined with the significant reduction of wear debris. For these reasons the Frisbee has the potential to provide a better balanced segmental loading reducing the degeneration of the joint surface and heterotopic ossification.

The influence of fixed sagittal plane centers of rotation on motion segment mechanics and range of motion in the cervical spine

2013 ◽  
Vol 46 (7) ◽  
pp. 1369-1375 ◽  
Author(s):  
Brian P. Kelly ◽  
Nephi A. Zufelt ◽  
Elizabeth J. Sander ◽  
Denis J. DiAngelo
Keyword(s):  
Cervical Spine ◽  
Range Of Motion ◽  
Sagittal Plane ◽  
Motion Segment
Sign in / Sign up

Export Citation Format

Share Document