A comparison of the biomechanical stability of pedicle-lengthening screws and traditional pedicle screws

2018 ◽  
Vol 100-B (4) ◽  
pp. 516-521 ◽  
Author(s):  
L. Qian ◽  
C. Jiang ◽  
P. Sun ◽  
D. Xu ◽  
Y. Wang ◽  
...  
Keyword(s):  
Fatigue Resistance ◽  
Fatigue Testing ◽  
Lumbar Vertebrae ◽  
Pedicle Screws ◽  
Cyclic Fatigue ◽  
Resistance Testing ◽  
Mineral Density ◽  
Biomechanical Stability ◽  
Pull Out ◽  
Fixation Stability

Aims The aim of this study was to compare the peak pull-out force (PPF) of pedicle-lengthening screws (PLS) and traditional pedicle screws (TPS) using instant and cyclic fatigue testing. Materials and Methods A total of 60 lumbar vertebrae were divided into six groups: PLS submitted to instant pull-out and fatigue-resistance testing (groups A1 and A2, respectively), TPS submitted to instant pull-out and fatigue-resistance testing (groups B1 and B2, respectively) and PLS augmented with 2 ml polymethylmethacrylate, submitted to instant pull-out and fatigue-resistance testing (groups C1 and C2, respectively). The PPF and normalized PPF (PPFn) for bone mineral density (BMD) were compared within and between all groups. Results In all groups, BMD was significantly correlated with PPF (r = 0.83, p < 0.001). The PPFn in A1 was significantly less than in B1 (p = 0.006) and C1 (p = 0.002). The PPFn of A2 was significantly less than in B2 (p < 0.001) and C2 (p < 0.001). The PPFn in A1, B1, and C1 was significantly greater than in A2 (p = 0.002), B2 (p = 0.027), and C2 (p = 0.003). There were no significant differences in PPFn between B1 and C1, or between B2 and C2. Conclusion Pedicle lengthening screws with cement augmentation can provide the same fixation stability as traditional pedicle screws and may be a viable clinical option. Cite this article: Bone Joint J 2018;100-B:516–21.

scholarly journals Correlation between the Computed Tomography Values of the Screw Path and Pedicle Screw Pullout Strength: An Experimental Study in Porcine Vertebrae

2020 ◽  
Vol 14 (3) ◽  
pp. 265-272
Author(s):  
Atsushi Ikeura ◽  
Taketoshi Kushida ◽  
Kenichi Oe ◽  
Yoshihisa Kotani ◽  
Muneharu Ando ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Bone Mineral Density ◽  
Pedicle Screw ◽  
Bone Mineral ◽  
Lumbar Vertebrae ◽  
Pedicle Screws ◽  
Mineral Density ◽  
Screw Insertion ◽  
Pull Out ◽  
Pull Out Strength

Study Design: Biomechanical study.Purpose: To assess the correlation between the computed tomography (CT) values of the pedicle screw path and screw pull-out strength.Overview of Literature: The correlation between pedicle screw pull-out strength and bone mineral density has been well established. In addition, several reports have demonstrated a correlation between bone mineral density and CT values. However, no previous biomechanical studies investigated the correlation between CT values and pedicle screw pull-out strength.Methods: Sixty fresh-frozen lumbar vertebrae from 6-month-old pigs were used. Before screw insertion, the CT values of the screw path were obtained for each sample. Specimens were then randomly divided into three equal groups. Each group had one of three pedicle screws inserted: 4.0-mm LEGACY (4.0-LEG), 4.5-mm LEGACY (4.5-LEG), or 4.5-mm SOLERA (4.5-SOL) (all from Medtronic Sofamor Danek Inc., Memphis, TN, USA). Each screw had a consistent 30-mm thread length. Axial pull-out testing was performed at a rate of 1.0 mm/min. Correlations between the CT values and pedicle screw pull-out strength were evaluated using Pearson’s correlation coefficient analysis.Results: The correlation coefficients between the CT values of the screw path and pedicle screw pull-out strength for the 4.0-LEG, 4.5-LEG, and 4.5-SOL groups were 0.836 (<i>p</i> <0.001), 0.780 (<i>p</i> <0.001), and 0.873 (<i>p</i> <0.001), respectively. Greater CT values were associated with greater screw pull-out strength.Conclusions: The CT values of the screw path were strongly positively correlated with pedicle screw pull-out strength, regardless of the screw type and diameter, suggesting that the CT values could be clinically useful for predicting pedicle screw pull-out strength.

scholarly journals Comparison of Apical Transportation, Centering Ability and Cyclic Fatigue Resistance of Four Rotary File Systems

2015 ◽  
Vol 03 (01) ◽  
pp. 012-019
Author(s):  
Ankita Sood ◽  
Varun Jindal ◽  
Ajay Chhabra ◽  
Arvind Arora ◽  
Ankur Vats
Keyword(s):  
Fatigue Resistance ◽  
Fatigue Testing ◽  
File Systems ◽  
Cyclic Fatigue ◽  
Root Canal Preparation ◽  
Maxillary Molars ◽  
Apical Transportation ◽  
Significant Difference ◽  
Before And After ◽  
Canal Transportation

Abstract Aim: The aim of this study was to evaluate the apical transportation, centering ability and cyclic fatigue resistance of Hero shaper, Twisted file, Hyflex file and RACE rotary file systems. Methods: Mesiobuccal roots of eighty maxillary molars were divided into four groups and instrumented with Hero shaper, Twisted file, Hyflex file and RACE rotary file systems with a final apical size being 25/.04. Apical deviation was assessed by the radiographic platform method that enables obtaining superimposed images of the first and last instrument used in root canal preparation in the same radiograph. Apical transportation was measured in millimeters with the aid of the AUTOCAD 2008 software. Forty canals were sectioned at 7mm from the apex and stereomicroscopic Images were taken at 6x magnification before and after instrumentation for evaluation of centering ability. The cyclic fatigue testing was conducted with the instrumentrotating freely at angles of curvature of 45 degree. Total 10 instruments were tested in each group. The instruments were rotated at 400rpm using the X-smart motor (Dentsply, Maillefer) until fracture occurred. Results: There was no statistically significant difference between the four groups in apical transportation and centering ability whereas twisted files showed the maximum cyclic fatigue resistance. Conclusion: The different rotary file systems provided minimum canal transportation and the twisted file performed significantly better in terms of cyclic fatigue resistance.

scholarly journals Assessment of the role of cross section on fatigue resistance of rotary files when used in reciprocation

2016 ◽  
Vol 10 (04) ◽  
pp. 541-545 ◽  
Author(s):  
Vadhana Sekar ◽  
Ranjith Kumar ◽  
Suresh Nandini ◽  
Suma Ballal ◽  
Natanasabapathy Velmurugan
Keyword(s):  
Cross Section ◽  
Fatigue Resistance ◽  
Fatigue Testing ◽  
Dynamic Testing ◽  
Cyclic Fatigue ◽  
Reciprocating Motion ◽  
Continuous Rotation ◽  
Significant Difference ◽  
Post Hoc

ABSTRACT Objective: The purpose of this study was to assess the role of cross section on cyclic fatigue resistance of One Shape, Revo-S SU, and Mtwo rotary files in continuous rotation and reciprocating motion in dynamic testing model. Materials and Methods: A total of 90 new rotary One Shape, Revo-S SU, and Mtwo files (ISO size 25, taper 0.06, length 25 mm) were subjected to continuous rotation or reciprocating motion. A cyclic fatigue testing device was fabricated with 60° angle of curvature and 5 mm radius. The dynamic testing of these files was performed using an electric motor which permitted the reproduction of pecking motion. All instruments were rotated or reciprocated until fracture occurred. The time taken for each instrument to fracture was recorded. All the fractured files were analyzed under a scanning electron microscope (SEM) to detect the mode of fracture. Statistical analysis was performed using one-way ANOVA, followed by Tukey's honestly significant difference post hoc test. Results: The time taken for instruments in reciprocating motion to fail under cyclic loading was significantly longer when compared with groups in continuous rotary motion. There was a statistically significant difference between Mtwo rotary and the other two groups in both continuous and reciprocating motion. One Shape rotary files recorded significantly longer duration to fracture resistance when compared with Revo-S SU files in both continuous and reciprocating motion. SEM observations showed that the instruments of all groups had undergone a ductile mode of fracture. Conclusion: Reciprocating motion improved the cyclic fatigue resistance of all tested groups.

scholarly journals Pedicle Screws Challenged: Lumbar Cortical Density and Thickness Are Greater in the Posterior Elements Than in the Pedicles

2019 ◽  
Vol 11 (1) ◽  
pp. 34-43
Author(s):  
Khalid Odeh ◽  
Alexander Rosinski ◽  
Jeremi Leasure ◽  
Dimitriy Kondrashov
Keyword(s):  
Lumbar Spine ◽  
Cortical Thickness ◽  
Lumbar Vertebrae ◽  
Pedicle Screws ◽  
Software Modeling ◽  
Mineral Density ◽  
Cortical Volume ◽  
Total Bone Mineral Density ◽  
Articular Process ◽  
Cortical Density

Study Design: Controlled laboratory study. Objective: To measure the total bone mineral density (BMD), cortical volume, and cortical thickness in seven different anatomical regions of the lumbar spine. Methods: Using computed tomography (CT) images, 3 cadaveric spines were digitally isolated by applying filters for cortical and cancellous bone. Each spine model was separated into 5 lumbar vertebrae, followed by segmentation of each vertebra into 7 anatomical regions of interest using 3-dimensional software modeling. The average Hounsfield units (HU) was determined for each region and converted to BMD with calibration phantoms of known BMD. These BMD measurements were further analyzed by the total volume, cortical volume, and cancellous volume. The cortical thickness was also measured. A similar analysis was performed by vertebral segment. St Mary’s Medical Center’s Institutional Review Board approved this study. No external funding was received for this work. Results: The lamina and inferior articular process contained the highest total BMD, thickest cortical shell, and largest percent volumes of cortical bone. The vertebral body demonstrated the lowest BMD. The BMDs of the L4 and L5 segments were lower; however, there were no statistically significant differences in BMD between the L1-L5 vertebral segments. Conclusion: Extrapedicular regions of the lumbar vertebrae, including the lamina and inferior articular process, contain denser bone than the pedicles. Since screw pullout strength relies greatly on bone density, the lamina and inferior articular processes may offer stronger fixation of the lumbar spine.

scholarly journals Cyclic Fatigue Comparison of TruNatomy, Twisted File, and ProTaper Next Rotary Systems

2020 ◽  
Vol 2020 ◽  
pp. 1-4
Author(s):  
Abdullah Mahmoud Riyahi ◽  
Amr Bashiri ◽  
Khalid Alshahrani ◽  
Saad Alshahrani ◽  
Hadi M. Alamri ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Fatigue Resistance ◽  
Fatigue Testing ◽  
Clinical Performance ◽  
Cyclic Fatigue ◽  
Tooth Structure ◽  
Multiple Comparison Test ◽  
Continuous Rotation ◽  
Number Of Cycles ◽  
Cycles To Failure

TruNatomy (TN; Dentsply Sirona, Maillefer, Ballaigues, Switzerland) is a newly released system that was not tested in any previous studies. The objective of this work is to evaluate cyclic fatigue resistance of the new file and compare it with the Twisted Files (TF) and ProTaper Next (PTN). Forty-five files were distributed into 3 groups: PTN X2 (size 25 and taper 0.06), TF (size 25 and taper 0.06), and TN prime file (size 26 and taper 0.04). Each group included 15 files. Lengths of all files were 25 mm. Cyclic fatigue testing was done using artificial stainless-steel canals with 60-degree curvature and 5 mm radius. Continuous rotation movement at 300 rpm was used until the file fractures. Time for file separation was recorded in seconds. The number of cycles to failure (NCF) mean and standard deviation for each group was calculated. For statistical analysis of data, ANOVA and Tukey’s multiple comparison test were used. Mean and standard deviation (SD) of NCF were 259 ± 37.2, 521.67 ± 63.07 and 846.67 ± 37.16 for PTN, TF, and TN respectively. TN on average had significantly the highest NCF compared with PTN (p<0.05) and TF (p<0.05). TruNatomy file showed superior cyclic fatigue resistance. With its potential to preserve tooth structure, this file offers a good cyclic fatigue advantage. However, future studies are required to evaluate other properties of this file and to examine its clinical performance.

scholarly journals Assessment of cyclic fatigue resistance of Protaper Next and WaveOne Gold in different kinematics

2020 ◽  
Vol 44 (1) ◽  
Author(s):  
Amira Galal Ismail ◽  
Manar Galal ◽  
Nehal Nabil Roshdy
Keyword(s):  
Fatigue Resistance ◽  
Fatigue Testing ◽  
Cyclic Fatigue ◽  
Rotation Group ◽  
Radius Of Curvature ◽  
Testing Device ◽  
Reciprocating Motion ◽  
Continuous Rotation ◽  
Custom Made ◽  
Rotation Motion

Abstract Background The purpose of the current study was to inspect and compare the influence of applying continuous rotation and reciprocation motions on the cyclic fatigue resistance of Protaper Next (PTN) file (X2) and WaveOne Gold (WOG) Primary file in simulated canals. Twenty Protaper Next files(X2) and 20 WaveOne Gold Primary files were included in this study. A cyclic fatigue testing device was employed to test the cyclic resistance of each file in different motions. The testing device has an artificial custom-made stainless-steel canal with a 60° angle of curvature and a 2-mm radius of curvature. The files were randomly divided into 4 groups; group 1: PTN in continuous rotation, group 2: PTN in reciprocation, group 3: WOG in continuous rotation and group 4: WOG in reciprocation. All the instruments were rotated until fracture occurred, and the time to fracture was recorded in seconds using a digital chronometer. The number of cycles to fracture (NCF) was calculated. The data were analyzed statistically (p < .05). Results Results represented that when using either continuous rotation motion or reciprocating motion, WOG files showed a significantly longer time until failure than PTN files (p < 0.001). The time till fracture increased significantly, when using both types of files with a reciprocating filing motion. Conclusion Within the confinement of this study, WOG file in reciprocation showed higher cyclic fatigue resistance than PTN in both continuous rotation and reciprocating motion. The reciprocating motion enhances both files behavior in terms of cyclic fatigue resistance.

scholarly journals Standardizing fatigue-resistance testing during electrical stimulation of paralysed human quadriceps muscles, a practical approach

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Martin Schmoll ◽  
Ronan Le Guillou ◽  
David Lobato Borges ◽  
Charles Fattal ◽  
Emerson Fachin-Martins ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Fatigue Resistance ◽  
Fatigue Testing ◽  
Knee Extension ◽  
Electrode Configuration ◽  
Resistance Testing ◽  
Positive Effects ◽  
Significant Difference ◽  
Dynamic Contractions ◽  
Isometric Torque

Abstract Background Rapid onset of muscular fatigue is still one of the main issues of functional electrical stimulation (FES). A promising technique, known as distributed stimulation, aims to activate sub-units of a muscle at a lower stimulation frequency to increase fatigue-resistance. Besides a general agreement on the beneficial effects, the great heterogeneity of evaluation techniques, raises the demand for a standardized method to better reflect the requirements of a practical application. Methods This study investigated the fatigue-development of 6 paralysed quadriceps muscles over the course of 180 dynamic contractions, evaluating different electrode-configurations (conventional and distributed stimulation). For a standardized comparison, fatigue-testing was performed at 40% of the peak-torque during a maximal evoked contraction (MEC). Further, we assessed the isometric torque for each electrode-configuration at different knee-extension-angles (70°–170°, 10° steps). Results Our results showed no significant difference in the fatigue-index for any of the tested electrode-configurations, compared to conventional-stimulation. We conjecture that the positive effects of distributed stimulation become less pronounced at higher stimulation amplitudes. The isometric torque produced at different knee-extension angles was similar for most electrode-configurations. Maximal torque-production was found at 130°–140° knee-extension-angle, which correlates with the maximal knee-flexion-angles during running. Conclusion In most practical applications, FES is intended to initiate dynamic movements. Therefore, it is crucial to assess fatigue-resistance by using dynamic contractions. Reporting the relationship between produced torque and knee-extension-angle can help to observe the stability of a chosen electrode-configuration for a targeted range-of-motion. Additionally, we suggest to perform fatigue testing at higher forces (e.g. 40% of the maximal evoked torque) in pre-trained subjects with SCI to better reflect the practical demands of FES-applications.

scholarly journals Comparison of Cyclic Fatigue Resistance of Five Heat Treated NiTi Rotary Systems in Single and Double Curved Canals.

2021 ◽  
Author(s):  
Mohammad Al-Obaida ◽  
Khalid Merdad ◽  
Ali Alkhamis ◽  
Muneer Khan Mohammed ◽  
Rahaf Al-Obaida ◽  
...  
Keyword(s):  
Fatigue Resistance ◽  
Fatigue Testing ◽  
Cyclic Fatigue ◽  
Radius Of Curvature ◽  
Double Curvature ◽  
Heat Treated ◽  
Separation Pattern ◽  
Vortex Blue ◽  
Number Of Cycles ◽  
Post Hoc

Abstract BackgroundThe aim of this study was to compare cyclic fatigue resistance (CFR) and separation patterns during rotating movement of five heat-treated nickel titanium files in both single and double-curved canals. MethodsCFR was compared between five groups of 24 files each: HyFlex® EDM, HyFlex™ CM, Vortex Blue®, Protaper Next®, and One Curve, by determining the time needed to fracture (TTF) and the number of cycles to failure (NCF) in a cyclic fatigue testing device with a single 5-mm radius of curvature (ROC) and 60° angle, and a double curvature; coronal curvature (5 mm ROC and 60° angle) and apical curvature (2 mm ROC and 70° angle). The separation pattern was evaluated, and file fragment separated length were measured. One-way ANOVA and Tukey’s post-hoc were used to compare statistical differences between the groups. Scanning Electron Microscope (SEM) was used to investigate the fracture sites. Results HyFlex™ CM files displayed significantly higher CFR, followed by HyFlex® EDM and Vortex Blue® in single curvature canals, and Protaper Next® (PTN) in the double curvature canals, as observed by TFF and NCF. PTN group had the highest tendency for files to extrude apically after separation in both curvatures. ConclusionHyFlex™ CM instruments have superior resistance to cyclic flexural fatigue within single canals with single and double curvatures, followed by HyFlex® EDM and Vortex Blue® instruments. Protaper Next® files followed by One Curve had the highest tendency to extrude apically after separationClinical relevanceHyFlex™ CM instruments showed the highest safety in preparing canals with single or double curvatures, considering CFR.

Biomechanics of Grade I degenerative lumbar spondylolisthesis. Part 2: Treatment with threaded interbody cages/dowels and pedicle screws

2001 ◽  
Vol 94 (1) ◽  
pp. 51-60 ◽  
Author(s):  
Sedat Çagli ◽  
Neil R. Crawford ◽  
Volker K. H. Sonntag ◽  
Curtis A. Dickman
Keyword(s):  
Pedicle Screw ◽  
Degenerative Spondylolisthesis ◽  
Pedicle Screws ◽  
Cyclic Fatigue ◽  
Pedicle Screw Fixation ◽  
Biomechanical Stability ◽  
Content Type ◽  
Degenerative Lumbar Spondylolisthesis ◽  
Lumbar Spondylolisthesis ◽  
Fine Print

Object. The authors sought to determine the biomechanical effectiveness of threaded interbody cages or dowels compared with that achieved using pedicle screw instrumentation in resisting Grade I lumbar spine degenerative spondylolisthesis. Methods. Thirty-three levels obtained from seven cadaveric lumbar spines were instrumented with cages or dowels, pedicle screw/rod instrumentation, or both. Entire specimens were loaded with nonconstraining torques. Each level was loaded with anteroposterior shear forces while an optical system was used to measure the specimen's motion at individual levels. Pedicle screw/rods outperformed interbody cages and dowels in treating spondylolisthesis. Cages or dowels alone provided only moderate biomechanical stability, and their effectiveness depended heavily on the integrity of the ligaments and remaining annulus, whereas the success of pedicle screw fixation relied predominantly on the integrity of the bone for solid fixation. Little biomechanical difference was demonstrated between cages and dowels; both devices were susceptible to loosening with cyclic fatigue. Conclusions. Biomechanically, cages or dowels alone were suboptimal for treating lumbar spondylolisthesis, especially compared with pedicle screw/rods. Threaded cages or dowels used together with pedicle screws/rods created the most stable construct.

scholarly journals Evaluation of cyclic fatigue resistance of modern Nickel-Titanium rotary instruments with continuous rotation

2017 ◽  
Vol 31 (2) ◽  
pp. 78-82
Author(s):  
Massimo Amato ◽  
Giuseppe Pantaleo ◽  
Dina Abdellatif ◽  
Andrea Blasi ◽  
Roberto Lo Giudice ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
Fatigue Resistance ◽  
Fracture Resistance ◽  
Fatigue Testing ◽  
Cyclic Fatigue ◽  
Nickel Titanium ◽  
Whitney Test ◽  
Ti Alloys ◽  
Rotary Instruments ◽  
Continuous Rotation

Aim: The aim of present study was to compare cyclic fatigue resistance of three modern Ni-Ti instruments used with continuous rotation. Materials and methods: For this study 3 groups of rotating instruments with continuous rotation (HyFlex EDM, Twisted File Adaptive, Revo S SU) have been used, each group consisted of 20 files. The various groups were subjected to cyclic fatigue testing through an artificial metal device. A statistical analysis with Kruskal-Wallis test and Mann-Whitney test was performed. Results: There were statistically significant differences between the three groups. The HyFlex EDM instruments have a fracture resistance slightly higher than the Twisted file and far higher than Revo S SU. Conclusions: Modern Ni-Ti alloys increase resistance of the rotating instruments to cyclic fatigue.

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