C1 Lateral Mass Displacement and Transverse Atlantal Ligament Failure in Jefferson's Fracture: A Biomechanical Study of the “Rule of Spence”

Neurosurgery ◽  
2017 ◽  
Vol 82 (2) ◽  
pp. 226-231 ◽  
Author(s):  
Rafeek O Woods ◽  
Serkan Inceoglu ◽  
Yusuf T Akpolat ◽  
Wayne K Cheng ◽  
Brice Jabo ◽  
...  
Keyword(s):  
High Speed ◽  
Lateral Displacement ◽  
Testing Machine ◽  
Biomechanical Study ◽  
Lateral Mass ◽  
Average Force ◽  
Bursting Fracture ◽  
Mass Displacement ◽  
Universal Material Testing Machine ◽  
Transverse Atlantal Ligament

Abstract BACKGROUND Jefferson's fracture, first described in 1927, represents a bursting fracture of the C1 ring with lateral displacement of the lateral masses. It has been determined that if the total lateral mass displacement (LMD) exceeds 6.9 mm, there is high likelihood of transverse atlantal ligament (TAL) rupture, and if LMD is less than 5.7 mm TAL injury is unlikely. Several recent radiographic studies have questioned the accuracy and validity of the “rule of Spence” and it lacks biomechanical support. OBJECTIVE To determine the amount of LMD necessary for TAL failure using modern biomechanical techniques. METHODS Using a universal material testing machine, cadaveric TALs were stretched laterally until failure. A high-resolution, high-speed camera was utilized to measure the displacement of the lateral masses upon TAL failure. RESULTS Eleven cadaveric specimens were tested (n = 11). The average LMD upon TAL failure was 3.2 mm (±1.2 mm). The average force required to cause failure of the TAL was 242 N (±82 N). From our data analysis, if LMD exceeds 3.8 mm, there is high probability of TAL failure. CONCLUSION Our findings suggest that although the rule of Spence is a conceptually valid measure of TAL integrity, TAL failure occurs at a significantly lower value than previously reported (P < .001). Based on our literature review and findings, LMD is not a reliable independent indicator for TAL failure and should be used as an adjunctive tool to magnetic resonance imaging rather an absolute rule.

Biomechanical evaluation of cervical lateral mass fixation: a comparison of the Roy-Camille and Magerl screw techniques

2004 ◽  
Vol 100 (3) ◽  
pp. 268-276 ◽  
Author(s):  
Cédric Barrey ◽  
Patrick Mertens ◽  
Claude Rumelhart ◽  
François Cotton ◽  
Jérôme Jund ◽  
...  
Keyword(s):  
Testing Machine ◽  
Biomechanical Study ◽  
Lateral Mass ◽  
Mineral Density ◽  
Vertebral Level ◽  
Content Type ◽  
Pullout Force ◽  
Significant Difference ◽  
The Difference ◽  
Fine Print

Object. The purpose of this study was to assess human cervical spine pullout force after lateral mass fixation involving two different techniques: the Roy-Camille and the Magerl techniques. Although such comparisons have been conducted previously, because of the heterogeneity of results and the importance of this procedure in clinical practice, it is essential to have data derived from a prospective and randomized biomechanical study involving a sufficient sample of human cervical spines. The authors also evaluated the influence of the sex, the vertebral level, the bone mineral density (BMD), the length of bone purchase, and the thickness of the anterior cortical purchase. Methods. Twenty-one adult cervical spines were harvested from fresh human cadavers. Computerized tomography was performed before and after placing 3.5-mm titanium lateral mass screws from C-3 to C-6. Pullout forces were evaluated using a material testing machine. The load was applied until the pullout of the screw was observed. A total of 152 pullout tests were available, 76 for each type of screw fixation. The statistical analysis was mainly performed using the Kaplan—Meier survival method. The mean pullout force was 266 ± 124 N for the Roy-Camille technique and 231 ± 94 N for the Magerl technique (p < 0.025). For the C3–4 specimen group, Roy-Camille screws were demonstrated to exert a significantly higher resistance to pullout forces (299 ± 114 N) compared with Magerl screws (242 ± 97 N), whereas no difference was found between the two techniques for the C5–6 specimen group (Roy-Camille 236 ± 122 N and Magerl 220 ± 86 N). Independent of the procedure, pullout strengths were greater at the C3–4 level (271 ± 114 N) than the C5–6 level (228 ± 105 N) (p < 0.05). No significant correlation between the cancellous BMD, the thickness of the anterior cortical purchase, the length of bone purchase, and maximal pullout forces was found for either technique. Conclusions. The difference between pullout forces associated with the Roy-Camille and the Magerl techniques was not as significant as has been previously suggested in the literature. It was interesting to note the influence of the vertebral level: Roy-Camille screws demonstrated greater pullout strength (23%) at the C3–4 vertebral level than Magerl screws but no significant difference between the techniques was observed at C5–6.

Comparison of the fast-start performances of closely related, morphologically distinct threespine sticklebacks (Gasterosteus spp.)

1996 ◽  
Vol 199 (12) ◽  
pp. 2595-2604 ◽  
Author(s):  
T Law ◽  
R Blake
Keyword(s):  
Angular Velocity ◽  
High Speed ◽  
High Performance ◽  
Gasterosteus Aculeatus ◽  
Morphological Characteristics ◽  
Maximum Velocity ◽  
Threespine Stickleback ◽  
Biomechanical Study ◽  
Maximum Acceleration ◽  
Fast Start

Fast-start escape performances for two species of threespine stickleback, Gasterosteus spp., were investigated using high-speed cinematography (400 Hz). The two fishes (not yet formally described, referred to here as benthic and limnetic) inhabit different niches within Paxton Lake, British Columbia, Canada, and are recent, morphologically distinct species. All escape responses observed for both species were double-bend C-type fast-starts. There were no significant differences between the species for any linear or angular parameter (pooled averages, both species: duration 0.048 s, distance 0.033 m, maximum velocity 1.10 m s-1, maximum acceleration 137 m s-2, maximum horizontal angular velocity 473.6 rad s-1 and maximum overall angular velocity 511.1 rad s-1). Benthics and limnetics have the greatest added mass (Ma) at 0.3 and 0.6 body lengths, respectively. The maximum Ma does not include the fins for benthics, but for limnetics the dorsal and anal fins contribute greatly to the maximum Ma. The deep, posteriorly placed fins of limnetics enable them to have a fast-start performance equivalent to that of the deeper-bodied benthics. Both the limnetic and benthic fishes have significantly higher escape fast-start velocities than their ancestral form, the anadromous threespine stickleback Gasterosteus aculeatus, suggesting that the high performance of the Paxton Lake sticklebacks is an evolutionarily derived trait. In this biomechanical study of functional morphology, we demonstrate that similar high fast-start performance can be achieved by different suites of morphological characteristics and suggest that predation might be the selective force for the high escape performance in these two fishes.

scholarly journals Development of gear dynamic performance testing machine

2021 ◽  
Vol 12 ◽  
pp. 20
Author(s):  
Ke Li ◽  
Bo Yu ◽  
Zhaoyao Shi ◽  
Zanhui Shu ◽  
Rui Li
Keyword(s):  
High Speed ◽  
Performance Test ◽  
Dynamic Testing ◽  
Mechanical Design ◽  
Dynamic Performance ◽  
External Disturbance ◽  
Testing Machine ◽  
High Stress ◽  
Performance Testing ◽  
Current Application

With the development of gears towards high temperature, high pressure, high speed and high stress, gear measurement, in which only the static geometric accuracy is considered, is unable to meet the current application requirements. While, the low precision and single function gear tester constrains the measurement of gear dynamic performance. For the resolution of this problem, based on the principle of gear system dynamics and several precision mechanical design techniques, a gear dynamic testing machine has been developed, providing new instruments for gear testing. On the basis of research of the principle of dynamic performance test, the primary measurement items of the testing machine have been determined. The measuring principles of each item and the driving and loading form of the testing machine have been examined. The measurement and control system of the testing machine and its corresponding software have been developed. The instrument can not only obtain the static precision index of the gear, but also obtain the dynamic performance index of the gear in variable working conditions. According to the actual test, the uncertainty of instrument is 3.8 μm and the external disturbance caused by the shaft vibration is less than 0.6 μm, which can meet the 5–6 grade precision gear testing requirement.

Hunting Stability Analysis of a New High-Speed Railway Vehicle Model Moving on Curved Tracks

2007 ◽  
Author(s):  
Yung-Chang Cheng ◽  
Sen-Yung Lee
Keyword(s):  
High Speed ◽  
Degrees Of Freedom ◽  
Lateral Displacement ◽  
Creep Model ◽  
Railway Vehicle ◽  
Nonlinear Creep ◽  
Car Body ◽  
Suspension Parameters ◽  
Virtual Boundary ◽  
Hunting Stability

A new dynamic model of railway vehicle moving on curved tracks is proposed. In this new model, the motion of the car body is considered and the motion of the tuck frame is not restricted by a virtual boundary. Based on the heuristic nonlinear creep model, the nonlinear coupled differential equations of the motion of a fourteen degrees of freedom car system, considering the lateral displacement and the yaw angle of the each wheelset, the truck frame and the car body, moving on curved tracks are derived in completeness. To illustrate the accuracy of the analysis, the limiting cases are examined. In addition, the influences of the suspension parameters on the critical hunting speeds evaluated via the linear and the nonlinear creep models respectively are studied. Furthermore, the influences of the suspension parameters on the critical hunting speeds evaluated via the fourteen degrees of freedom car system and the six degrees of freedom truck system, which the motion of the tuck frame is restricted by a virtual boundary, are compared.

scholarly journals Navigation-Assisted Posterior Open Reduction and Internal Fixation in a C-CLAMP Fashion for an Isolated C1 Fracture

2020 ◽  
Author(s):  
Daniele Starnoni ◽  
Timo Ecker ◽  
Juan Barges-Coll
Keyword(s):  
Neck Pain ◽  
Internal Fixation ◽  
Motor Vehicle ◽  
Motor Vehicle Accident ◽  
Lateral Displacement ◽  
Lateral Mass ◽  
Transverse Ligament ◽  
Alar Ligament ◽  
The Right

AbstractC1 fractures with an intact transverse ligament are usually treated conservatively. Patients who present with a progressive diastasis of bone fragments and a progressive articular subluxation mainly attributed to progressive lengthening of the transverse ligament (TAL) fibers can be treated with a C1 “C-clamp” fusion.A 75-year-old male who sustained a motor vehicle accident was neurologically intact. A computed tomography (CT) imaging demonstrated a Jefferson's type-C1 fracture with a slight lateral displacement of the C1 left lateral mass (LM) and a rotatory subluxation on the right. MRI showed an intact TAL and demonstrated an isolated rupture of the left alar ligament. Conservative treatment was chosen. Radiographic follow-up showed, at 3 months, progressive lateral mass displacement, most likely due to elongation of the TAL fibers; this was also associated with a persistent mechanical neck pain. For this reason, we performed a posterior reduction and internal fixation in a C-clamp fashion by placement of C1 lateral mass screws and posterior compression sparing the C1–2 joint. Using navigation, a 3.5-mm screw was inserted into the LM bilaterally. The screw heads were then connected with a rod and compression was applied before tightening. Postoperative CT scan demonstrated a satisfying reduction and further imaging will be made during the follow-up. The patient had a considerable relief of neck pain. Simple lateral mass fixation with C-clamp technique is a reasonable option in case of isolated C1 fractures in patients who have failed conservative management while preserving the range of motion (ROM) at the atlanto–axial joint.The link to the video can be found at: https://youtu.be/x8bsVwzCt_M.

scholarly journals Effects of Zr, Y on the Microstructure and Properties of As-Cast Cu-0.5Y-xZr (wt.%) Alloys

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1084
Author(s):  
Dong Liang ◽  
Ning Wang ◽  
Yuxiang Wang ◽  
Zhenjie Liu ◽  
Ying Fu
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Tensile Strength ◽  
Copper Alloys ◽  
Testing Machine ◽  
Elongation Rate ◽  
Nominal Composition ◽  
Microstructure And Properties ◽  
Universal Material Testing Machine ◽  
Material Testing Machine

In this paper, the microstructure and properties of as-cast Cu-Y-Zr alloys with different Zr content were studied in order to investigate whether the precipitates in copper alloys would interact with each other by adding Y and Zr simultaneously. As-cast Cu-0.5Y-xZr (wt.%, x = 0.05 and 0.1, nominal composition) alloys were prepared by vacuum melting in this study. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and transmission electron microscopy (TEM) were used to observe the microstructure of the alloys. The mechanical properties of the alloys were tested by universal material testing machine at room temperature. The effects of Zr content on the microstructure and mechanical properties of the alloys were explored. As shown by the research results, in the as-cast Cu-0.5Y-xZr (wt.%) alloys, the precipitated phase was the Cu5Y/Cu5Zr phase and ranged from 10 nm to 70 nm in size; when the Zr content increased from 0.05 wt.% to 0.1 wt.%, both the tensile strength and elongation rate of the alloys increased; when the Zr content was 0.1 wt.%, the tensile strength was 225 MPa and the elongation rate was 22.5%.

Effect of Slag Composition on Fatigue Life of High Speed Wheel Steel

2013 ◽  
Vol 675 ◽  
pp. 264-269
Author(s):  
Yu Tang
Keyword(s):  
Fatigue Life ◽  
High Speed ◽  
Fatigue Testing ◽  
Testing Machine ◽  
Oxide Inclusion ◽  
Wheel Steel ◽  
Al2o3 Content ◽  
Confocal Laser ◽  
Composition Analysis ◽  
In Situ Observation

In order to improve fatigue life of wheel steel, secondary-refining process was done with Al-deoxidation and slag of high basicity, high Al2O3 content and low oxidizing property. By morphology observation and composition analysis with FESEM, it is found that during LF-VD process, by slag-steel-inclusion interaction, Al2O3 inclusions could transform to MgO-Al2O3 spinel, and later on to CaO-MgO-Al2O3 inclusions, which are inclined to be eliminated by floatation, lowering T[O] content to 0.0007%, enhancing fatigue life of wheel steel. By In-Situ observation with CONFOCAL laser scanning microscope, it is found that MnS precipitates during solidification process, which would core oxide inclusion to form MnS-oxide complex inclusion, contributing to fatigue life improvement of wheel steel. By INSTRON fatigue testing machine, it is found that by successful inclusion control, tested samples achieve ultra-high cycle of 108 above, realizing experimental purpose of improving fatigue life of wheel steel, boosting domestic production process of CRH high speed wheel steel.

Morphology, Mechanical and Thermal Properties of the Blends of Poly(Trimethylene Terephthalate)/Acrylonitrile-Styrene-Acrylic Copolymer

2014 ◽  
Vol 665 ◽  
pp. 348-351
Author(s):  
Shu Fang Lv ◽  
Shi Jie Niu ◽  
Ying Bin Liu ◽  
Ming Tao Run
Keyword(s):  
Thermal Aging ◽  
Testing Machine ◽  
Color Difference ◽  
Good Effect ◽  
Mechanical And Thermal Properties ◽  
Acrylic Copolymer ◽  
Copolymer Blends ◽  
Trimethylene Terephthalate ◽  
Universal Material Testing Machine ◽  
Material Testing Machine

Poly (trimethylene terephthalate)/acrylonitrile-styrene-acrylic copolymer blends were prepared and their morphology, thermal aging and mechanical properties were investigated by using the polarized optical microscopy, universal material testing machine and color-difference meter, repectively. The results suggest that ASA and PTT are partially miscible in the blends, and when TPEE content is 50%, a bi-continuous phases form in the blend. The PTT’s spherulites in the blends become smaller and even microcrystallites with increasing ASA content. ASA component has good effect on toughen PTT by increasing blends’ impact strength but depresses the tensile strength of the blends. ASA has no influence on the thermal aging properties of PTT, and PTT/ASA blend has better thermal aging resistance than that of PTT/ABS blend.

The Compatibility Research of the Organic Montmorillonites with SEBS

2014 ◽  
Vol 1044-1045 ◽  
pp. 128-132
Author(s):  
Chen Jie Shi ◽  
Xiao Yan Li ◽  
Xia Wang ◽  
Yuan Wen Wang ◽  
Zhen Lu ◽  
...  
Keyword(s):  
Testing Machine ◽  
Melt Blending ◽  
X Ray Diffraction ◽  
Exchange Method ◽  
Organic Modification ◽  
Layer Spacing ◽  
Ft Ir ◽  
Universal Material Testing Machine ◽  
Material Testing Machine

To improve the compatibility of montmorillonite (MMT) with polymer. A kind of organic intercalation agent was applied in the intercalating organic modification of montmorillonite (OMMT) through ion exchange method, and a kind of silane coupling agent was further used to do the organic treatment. The SEBS/OMMTs composites were also prepared by melt blending. Structure and characterization of the modified MMTs were investigated by Fourier Transform infrared (FT-IR), wide angle X-ray diffraction (WAXRD), and the thermal stability were characterized by Thermogravimetric analysis (TGA). The dispersion status of MMTs were evaluated by scanning electron microscope (SEM) and the composites were tested by universal material testing machine. The FTIR results initial displayed that OMMTs had the absorption peak of organic functional groups. The XRD results showed that compared to Na+-MMT(1.47 nm), the layer spacing of H-OMMT increased to 3.27 nm, the above two results showed the organic modification of MMT had succeed. The results of TGA showed that OMMTs had a weight loss of organics. The SEM demonstrated that H-OMMT had the best dispersion status in SEBS matrix, and Na+-MMT was the worst.

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