scholarly journals Biomechanical Evaluation of the MACSTL Internal Fixator for Thoracic Spinal Stabilisation

2008 ◽  
Vol 77 (1) ◽  
pp. 97-102 ◽  
Author(s):  
R. Veselý ◽  
Z. Florián ◽  
P. Wendsche ◽  
J. Tošovský
Keyword(s):  
Thoracic Spine ◽  
Spinal Column ◽  
Spinal Fractures ◽  
Internal Fixator ◽  
Additional Advantage ◽  
System A ◽  
Thoracic Spinal ◽  
Mechanical Study ◽  
Surgical Tactics ◽  
The Stability

Unstable fractures of the thoracic spine in humans represent a serious social and economic issue. They may lead to persistent consequences and chronic disease. The anatomical and biomechanical characteristics of the thoracic spine are different from all the other spinal parts due to its higher mobility. The vertebrae of the chest area are less mobile, conferring a higher degree of rigidity to the spine. To destabilize this relatively rigid system, a considerable force is necessary. The treatment of unstable spinal fractures is solely surgical. The decompression of the spinal canal with reposition and stabilisation of the fracture is indicated urgently. This intervention is performed mostly from the posterior approach in the first phase. However, the anterior spinal column is the structure responsible for the stability of the spine. Therefore, the recent advances in spine surgery focus on this area of expertise. For this reason, we carried out a bio-mechanical study aimed at assessing the effectiveness of two surgical tactics used. The study consisted of comparative experiments performed by computer-aided device on segments of pig cadavers (n = 5). The experiment involved a comparison of segments of the thoracic spine under the following conditions: an anatomically intact segment, a spine segment with an artificially created anterior instability, and a segment with an applied internal fixator. The experiment compared the mechanical characteristics of these segments. The experiment has demonstrated that after application of the internal fixator used for stabilisation of the injured anterior spinal column at defined pre-loading of 200 N, the stability of damaged spinal segment in torsion increased twofold. It was also verified that sufficient stability can be ensured using the Modular Anterior Construct System (MACSTL) implant for ventral stabilisation of thoracic spine unstable injuries. Endoscopic application of this implant represents an additional advantage of this surgical procedure.

Biomechanics of Human Thoracic Ribs

1998 ◽  
Vol 120 (1) ◽  
pp. 100-104 ◽  
Author(s):  
N. Yoganandan ◽  
F. A. Pintar
Keyword(s):  
Thoracic Spine ◽  
Large Population ◽  
Spinal Column ◽  
Biomechanical Properties ◽  
Cross Sectional ◽  
Three Point Bending ◽  
Thoracic Spinal ◽  
Test Parameters ◽  
Human Cadavers ◽  
Ultimate Failure

Considerable advances have been made to determine the failure biomechanical properties of the human thoracic spinal column and its components. Except for a few fundamental studies, there is a paucity of such data for the costovertebral elements. The present study was designed to determine the biomechanics of the human thoracic spine ribs from a large population. Seventh and eighth ribs bilaterally were tested from 30 human cadavers using the principles of three-point bending techniques to failure. Biomechanical test parameters included the cross-sectional area (core, marrow, and total), moment of inertia, failure load, deflection, and the Young’s elastic modulus. The strength-related results indicated no specific bias with respect to anatomical level and hemisphere (right or left), although the geometry-related variables demonstrated statistically significant differences (p < 0.05) between the seventh and the eighth ribs. This study offers basic biomechanical information on the ultimate failure and geometric characteristics of the human thoracic spine ribs.

scholarly journals Biomechanics of transvertebral screw fixation in the thoracic spine: an in vitro study

2016 ◽  
Vol 25 (2) ◽  
pp. 187-192 ◽  
Author(s):  
Nestor G. Rodriguez-Martinez ◽  
Amey Savardekar ◽  
Eric W. Nottmeier ◽  
Stephen Pirris ◽  
Phillip M. Reyes ◽  
...  
Keyword(s):  
Pedicle Screw ◽  
Thoracic Spine ◽  
Axial Rotation ◽  
Lateral Bending ◽  
Motion Segment ◽  
Thoracic Spinal ◽  
Flexion Extension ◽  
Intact Condition ◽  
The Mean ◽  
The Stability

OBJECTIVE Transvertebral screws provide stability in thoracic spinal fixation surgeries, with their use mainly limited to patients who require a pedicle screw salvage technique. However, the biomechanical impact of transvertebral screws alone, when they are inserted across 2 vertebral bodies, has not been studied. In this study, the authors assessed the stability offered by a transvertebral screw construct for posterior instrumentation and compared its biomechanical performance to that of standard bilateral pedicle screw and rod (PSR) fixation. METHODS Fourteen fresh human cadaveric thoracic spine segments from T-6 to T-11 were divided into 2 groups with similar ages and bone quality. Group 1 received transvertebral screws across 2 levels without rods and subsequently with interconnecting bilateral rods at 3 levels (T8–10). Group 2 received bilateral PSR fixation and were sequentially tested with interconnecting rods at T7–8 and T9–10, at T8–9, and at T8–10. Flexibility tests were performed on intact and instrumented specimens in both groups. Presurgical and postsurgical O-arm 3D images were obtained to verify screw placement. RESULTS The mean range of motion (ROM) per motion segment with transvertebral screws spanning 2 levels compared with the intact condition was 66% of the mean intact ROM during flexion-extension (p = 0.013), 69% during lateral bending (p = 0.015), and 47% during axial rotation (p < 0.001). The mean ROM per motion segment with PSR spanning 2 levels compared with the intact condition was 38% of the mean intact ROM during flexion-extension (p < 0.001), 57% during lateral bending (p = 0.007), and 27% during axial rotation (p < 0.001). Adding bilateral rods to the 3 levels with transvertebral screws decreased the mean ROM per motion segment to 28% of intact ROM during flexion-extension (p < 0.001), 37% during lateral bending (p < 0.001), and 30% during axial rotation (p < 0.001). The mean ROM per motion segment for PSR spanning 3 levels was 21% of intact ROM during flexion-extension (p < 0.001), 33% during lateral bending (p < 0.001), and 22% during axial rotation (p < 0.001). CONCLUSIONS Biomechanically, fixation with a novel technique in the thoracic spine involving transvertebral screws showed restoration of stability to well within the stability provided by PSR fixation.

scholarly journals History of posterior thoracic instrumentation

2004 ◽  
Vol 16 (1) ◽  
pp. 1-4 ◽  
Author(s):  
Harshpal Singh ◽  
Scott Y. Rahimi ◽  
David J. Yeh ◽  
David Floyd
Keyword(s):  
Multiple Stressors ◽  
Spinal Injury ◽  
Posterior Instrumentation ◽  
Spinal Instrumentation ◽  
Spinal Column ◽  
Spinal Fractures ◽  
Thoracic Spinal ◽  
History Of ◽  
Central Meaning ◽  
Historical Treatment

The term “backbone” appears in many expressions used in modern day society. In any scenario, it has one central meaning: stability. Best defined as a foundation that is able to sustain multiple stressors without adversely affecting integrity, the commonly and appropriately termed backbone of humans is the spinal column. As the central focus of stability in our species, the spine is subject to a great degree of trauma and mechanical forces. A variety of methods have been developed throughout history in the treatment of spinal column injury. Initial treatment involved the use of simple traction devices for the reduction of spinal fractures; these have evolved to include the current insertion of spinal instrumentation. The authors review the historical treatment and development of posterior instrumentation for thoracic spinal injury.

NPLs — The Solution Recipe for Albania

2015 ◽  
Vol 3 (1) ◽  
pp. 48
Author(s):  
Elona Shehu ◽  
Elona Meka
Keyword(s):  
Interest Rate ◽  
Negative Relationship ◽  
Banking System ◽  
Gdp Growth ◽  
System A ◽  
Analysis Technique ◽  
Recent Financial Crisis ◽  
The Stability ◽  
Asset Quality ◽  
Macroeconomic Determinants

The quality of the loan portfolio in Albanian banking system is facing many obstacles during the last decade. In this paper we look at possible determinants of assets quality. During the recent financial crisis commercial banks were confronted with deteriorating asset quality that threatened not only the banking industry, but also the stability of the entire financial system. This study aims to examine the correlation between non-performing loans and the macroeconomic determinants in Albania during the last decade. NPLs are considered to be of a high importance as they represent the high risk exposure of banking system. A solid bank with healthy assets increases the market efficiency. Our approach is based on a panel data regression analysis technique from 2005-2015. Within this methodology this study finds robust evidence on the existing relationship between lending interest rate, real GDP growth and NPLs. We expect to find a negative relationship between lending interest rate and asset quality. Further we assume an inverse relationship between GDP growth and non-performing loans, suggesting that NPLs decrease if the economy is growing. Furthermore this study proposes a solution platform, which looks deeper into the possibility of creating a secondary active market for troubled loans, restructuring the banking system or implementing the Podgorica model. This research paper opens a new lieu of discussion in terms of academic debates and decision-making policies.

Towards a new design with generic modeling and adaptive control of a transformable quadrotor

2021 ◽  
pp. 1-31
Author(s):  
S.H. Derrouaoui ◽  
Y. Bouzid ◽  
M. Guiatni
Keyword(s):  
Adaptive Control ◽  
Control Strategy ◽  
Experimental Tests ◽  
Generic Model ◽  
System Control ◽  
System A ◽  
Viable Solution ◽  
Generic Modeling ◽  
Adaptive Control Strategy ◽  
The Stability

Abstract Recently, transformable Unmanned Aerial Vehicles (UAVs) have become a subject of great interest in the field of flying systems, due to their maneuverability, agility and morphological capacities. They can be used for specific missions and in more congested spaces. Moreover, this novel class of UAVs is considered as a viable solution for providing flying robots with specific and versatile functionalities. In this paper, we propose (i) a new design of a transformable quadrotor with (ii) generic modeling and (iii) adaptive control strategy. The proposed UAV is able to change its flight configuration by rotating its four arms independently around a central body, thanks to its adaptive geometry. To simplify and lighten the prototype, a simple mechanism with a light mechanical structure is proposed. Since the Center of Gravity (CoG) of the UAV moves according to the desired morphology of the system, a variation of the inertia and the allocation matrix occurs instantly. These dynamics parameters play an important role in the system control and its stability, representing a key difference compared with the classic quadrotor. Thus, a new generic model is developed, taking into account all these variations together with aerodynamic effects. To validate this model and ensure the stability of the designed UAV, an adaptive backstepping control strategy based on the change in the flight configuration is applied. MATLAB simulations are provided to evaluate and illustrate the performance and efficiency of the proposed controller. Finally, some experimental tests are presented.

Monostotic fibrous dysplasia of the thoracic spine: clinopathological description and follow up

2004 ◽  
Vol 100 (4) ◽  
pp. 378-381 ◽  
Author(s):  
Mehmet Arazi ◽  
Onder Guney ◽  
Mustafa Ozdemir ◽  
Omer Uluoglu ◽  
Nuket Uzum
Keyword(s):  
Fibrous Dysplasia ◽  
Thoracic Spine ◽  
Histopathological Examination ◽  
En Bloc Resection ◽  
Spinal Tumors ◽  
En Bloc ◽  
Content Type ◽  
Thoracic Spinal ◽  
Fine Print

✓ The authors report the case of a 53-year-old woman with monostotic fibrous dysplasia of the thoracic spine. The patient presented with a 1-month history of pain in the thoracic spinal region. En bloc resection of the lesion was successfully performed via a transthoracic approach, and a histopathological examination confirmed the diagnosis of fibrous dysplasia. At 24-month follow-up examination, pain and vertebral instability were absent. The findings in this case illustrate that, although very rare, monostotic fibrous dysplasia of the thoracic spine should be considered in the differential diagnosis of spinal tumors. Although a consensus for management of this disease has not been achieved, the authors recommend radical removal of all involved bone as well as internal fixation or bone graft—assisted fusion to achieve long-term stabilization.

Study on Self-Excited Vibration Mechanism of Wheel-Rail Lateral Contact System

2013 ◽  
Vol 427-429 ◽  
pp. 257-261
Author(s):  
Li Xia Sun ◽  
Jian Wei Yao ◽  
Fu Guo Hou ◽  
Xin Zhao
Keyword(s):  
Feedback Mechanism ◽  
Point Of View ◽  
Contact System ◽  
Vibration System ◽  
Lateral Contact ◽  
System A ◽  
Vibration Model ◽  
Excited Vibration ◽  
Vibration Mechanism ◽  
The Stability

In order to investigate self-excited vibration mechanism of wheel-rail lateral contact system, a two DOF elasticity position wheelset lateral vibration model is established which considers the dry friction; the mechanism of the wheelset lateral self-excited vibration is investigated from the energy point of view. It shows that: the bifurcation diagram of this wheel-rail lateral contact system has a supercritical Hopf bifurcation. The energy of self-excited vibration derives from a part of traction energy; the creep rate in the wheel-rail system act as a feedback mechanism in the wheelset lateral self-excited vibration system. The stability of the wheelset self-excited vibration system depends mainly on the total energy removed from and imported into the system.

Solving Vlasov-Poisson-Fokker-Planck Equations using NRxx method

2017 ◽  
Vol 21 (3) ◽  
pp. 782-807 ◽  
Author(s):  
Yanli Wang ◽  
Shudao Zhang
Keyword(s):  
Splitting Method ◽  
Linear Convergence ◽  
Mass Conservation ◽  
System A ◽  
Spectral Convergence ◽  
The Stability ◽  
The Moment ◽  
Stability And Accuracy ◽  
Fokker Planck Equations ◽  
Fokker Planck

AbstractWe present a numerical method to solve the Vlasov-Poisson-Fokker-Planck (VPFP) system using the NRxx method proposed in [4, 7, 9]. A globally hyperbolic moment system similar to that in [23] is derived. In this system, the Fokker-Planck (FP) operator term is reduced into the linear combination of the moment coefficients, which can be solved analytically under proper truncation. The non-splitting method, which can keep mass conservation and the balance law of the total momentum, is used to solve the whole system. A numerical problem for the VPFP system with an analytic solution is presented to indicate the spectral convergence with the moment number and the linear convergence with the grid size. Two more numerical experiments are tested to demonstrate the stability and accuracy of the NRxx method when applied to the VPFP system.

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