The biomechanical evaluation of calcium phosphate cements for use in vertebroplasty

2006 ◽  
Vol 4 (2) ◽  
pp. 154-159 ◽  
Author(s):  
Suk-Joo Hong ◽  
Youn-Kwan Park ◽  
Jung Hyuk Kim ◽  
Soon Hyuck Lee ◽  
Kyung Nam Ryu ◽  
...  
Keyword(s):  
Calcium Phosphate ◽  
Biomechanical Properties ◽  
Second Phase ◽  
Thoracic Vertebrae ◽  
Compression Tests ◽  
Initial Stiffness ◽  
Compression Fractures ◽  
Thoracolumbar Region ◽  
Before And After ◽  
Human Cadavers

Object The authors evaluate the biomechanical properties of vertebral bodies (VBs) stabilized with calcium phosphate (CaP) cements for use in vertebroplasty in comparison with polymethylmethacrylate (PMMA). Methods In the first phase of the study, 73 VBs (T3–L2; thoracic region [T3–8] and thoracolumbar region [T9–L2]) were collected from seven fresh human cadavers. Compression tests were performed before and after vertebroplasty using PMMA (compression strength 80 MPa) and three kinds of CaP cements—CaP1 (5 MPa), CaP2 (20 MPa), and CaP3 (50 MPa). The authors compared the maximal compression loads (MCLs) and stiffness before and after vertebroplasty in each of the four cement groups. In the second phase of the study, 18 paired spinal units (PSUs) were collected from three fresh human cadavers, and the authors injected two types of cement selected from the first phase of the study into the lower level of six PSUs. They compared the MCLs of the untreated and two treated groups (there were six PSUs in each type of group) to analyze the tendency of inducing compression fractures in the upper level of the PSUs. The MCLs of the PMMA-injected vertebrae were significantly increased after vertebroplasty. The MCL levels of the CaP3-injected vertebrae and the CaP2-injected thoracolumbar vertebrae were decreased from those of untreated vertebrae without being significant. The MCLs of CaP1-injected vertebrae and CaP2-injected thoracic vertebrae were significantly decreased after vertebroplasty. The stiffness of all cement groups was decreased after vertebroplasty compared with initial stiffness, significantly so in all three thoracic CaP groups. In the second compression test with PSUs, the MCLs of the CaP2- and CaP3-injected PSUs were not significantly different from those of the untreated control PSUs. Conclusions The CaP3-injected vertebrae restored the MCLs of human vertebrae closer to their initial levels than the PMMA-injected vertebrae did. The CaP2- and CaP3-injected PSUs showed no tendency to induce compression fractures in adjacent VBs.

Biomechanics of Lumbar Pedicle Screw/Plate Fixation in Trauma

Neurosurgery ◽  
1990 ◽  
Vol 27 (6) ◽  
pp. 873-881 ◽  
Author(s):  
Narayan Yoganandan ◽  
Sanford J. Larson ◽  
Frank Pintar ◽  
Dennis J. Maiman ◽  
John Reinartz ◽  
...  
Keyword(s):  
Plate Fixation ◽  
Anterior Column ◽  
Posterior Fixation ◽  
Initial Stiffness ◽  
Before And After ◽  
Human Cadavers ◽  
Failure Loads ◽  
Control Failure ◽  
Stiffness Characteristics ◽  
Strength And Stiffness

Abstract This investigation was conducted to determine alterations in the biomechanical strength and stiffness characteristics of the lumbar spine fixated with Steffee instrumentation. Comparative studies of these parameters were conducted using seven lumbar columns from fresh human cadavers. Three runs were conducted on each T12-L5 column: control, injured, and fixated. The specimens were loaded under the compression-flexion mode until failure (control run) and then reloaded (injury run) to the failure deformation determined in the control run. Screw/plates were then inserted one level proximal and distal to injury, and the specimens were reloaded (fixation run). Radiographs were taken before and after each trial. Data on deformation and force histories were gathered. The load-deflection response of the injured and fixated specimens were bimodal with two representative stiffnesses. Control failure loads and stiffnesses were higher than those for the injured (P < 0.001) or fixated (P < 0.01) spine. Initial stiffness was significantly higher for the fixated than for injured columns (P < 0.001), but the final stiffnesses were similar. The increase in the initial stiffness in the fixated specimen compared to the injured specimen indicates the strength added to the posterior region of the spine. The relatively smaller alteration in the final stiffness between the fixated and the injured columns, corresponding to the load shared by the anterior column, may suggest that, above a critical strain level, the anterior column absorbs a higher portion of the external load and posterior fixation may be inadequate as sole treatment in trauma.

The influence of osteopathic correction on the rate of various rhythms of the body

2019 ◽  
pp. 64-71 ◽  
Author(s):  
A. E. Chernikova ◽  
Yu. P. Potekhina
Keyword(s):  
Heart Rate ◽  
Respiratory Rate ◽  
Age Groups ◽  
Biomechanical Properties ◽  
Dispersion Analysis ◽  
The Body ◽  
Body Tissues ◽  
Age Related ◽  
Significant Difference ◽  
Before And After

Introduction. An osteopathic examination determines the rate, the amplitude and the strength of the main rhythms (cardiac, respiratory and cranial). However, there are relatively few studies in the available literature dedicated to the influence of osteopathic correction (OC) on the characteristics of these rhythms.Goal of research — to study the influence of OC on the rate characteristics of various rhythms of the human body.Materials and methods. 88 adult osteopathic patients aged from 18 to 81 years were examined, among them 30 men and 58 women. All patients received general osteopathic examination. The rate of the cranial rhythm (RCR), respiratory rate (RR) heart rate (HR), the mobility of the nervous processes (MNP) and the connective tissue mobility (CTM) were assessed before and after the OC session.Results. Since age varied greatly in the examined group, a correlation analysis of age-related changes of the assessed rhythms was carried out. Only the CTM correlated with age (r=–0,28; p<0,05) in a statistically significant way. The rank dispersion analysis of Kruskal–Wallis also showed statistically significant difference in this indicator in different age groups (p=0,043). With the increase of years, the CTM decreases gradually. After the OC, the CTM, increased in a statistically significant way (p<0,0001). The RCR varied from 5 to 12 cycles/min in the examined group, which corresponded to the norm. After the OC, the RCR has increased in a statistically significant way (p<0,0001), the MNP has also increased (p<0,0001). The initial heart rate in the subjects varied from 56 to 94 beats/min, and in 15 % it exceeded the norm. After the OC the heart rate corresponded to the norm in all patients. The heart rate and the respiratory rate significantly decreased after the OC (р<0,0001).Conclusion. The described biorhythm changes after the OC session may be indicative of the improvement of the nervous regulation, of the normalization of the autonomic balance, of the improvement of the biomechanical properties of body tissues and of the increase of their mobility. The assessed parameters can be measured quickly without any additional equipment and can be used in order to study the results of the OC.

scholarly journals Mediastinal anatomical landmarks, their variants and tips for video-assisted thoracoscopic navigation during oesophageal extirpation

2021 ◽  
Author(s):  
Sergey Dydykin ◽  
Friedrich Paulsen ◽  
Tatyana Khorobykh ◽  
Natalya Mishchenko ◽  
Marina Kapitonova ◽  
...  
Keyword(s):  
Prone Position ◽  
Anatomical Study ◽  
Structural Features ◽  
Posterior Mediastinum ◽  
Visual Navigation ◽  
Anatomical Landmarks ◽  
Video Assisted ◽  
Before And After ◽  
Human Cadavers ◽  
The Right

Abstract Purpose There is no systematic description of primary anatomical landmarks that allow a surgeon to reliably and safely navigate the superior and posterior mediastinum’s fat tissue spaces near large vessels and nerves during video-assisted endothoracoscopic interventions in the prone position of a patient. Our aim was to develop an algorithm of sequential visual navigation during thoracoscopic extirpation of the esophagus and determine the most permanent topographic and anatomical landmarks allowing safe thoracoscopic dissection of the esophagus in the prone position. Methods The anatomical study of the mediastinal structural features was carried out on 30 human cadavers before and after opening the right pleural cavity. Results For thoracoscopic extirpation of the esophagus in the prone position, anatomical landmarks are defined, their variants are assessed, and an algorithm for their selection is developed, allowing their direct visualization before and after opening the mediastinal pleura. Conclusion The proposed algorithm for topographic and anatomical navigation based on the key anatomical landmarks in the posterior mediastinum provides safe performance of the video-assisted thoracoscopic extirpation of the esophagus in the prone position.

scholarly journals Biomechanical properties of the bone during implant placement

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Ádám László Nagy ◽  
Zsolt Tóth ◽  
Tamás Tarjányi ◽  
Nándor Tamás Práger ◽  
Zoltán Lajos Baráth
Keyword(s):  
Bone Structure ◽  
Biomechanical Properties ◽  
Control Group ◽  
Dynamic Tests ◽  
Bone Model ◽  
Implant Placement ◽  
Significant Difference ◽  
Before And After ◽  
Group 2 ◽  
Post Hoc

Abstract Background In this research the biomechanical properties of a bone model was examined. Porcine ribs are used as experimental model. The objective of this research was to investigate and compare the biomechanical properties of the bone model before and after implant placement. Methods The bone samples were divided in three groups, Group 1 where ALL-ON-FOUR protocol was used during pre-drilling and placing the implants, Group 2 where ALL-ON-FOUR protocol was used during pre-drilling, and implants were not placed, and Group 3 consisting of intact bones served as a control group. Static and dynamic loading was applied for examining the model samples. Kruskal–Wallis statistical test and as a post-hoc test Mann–Whitney U test was performed to analyze experimental results. Results According to the results of the static loading, there was no significant difference between the implanted and original ribs, however, the toughness values of the bones decreased largely on account of predrilling the bones. The analysis of dynamic fatigue measurements by Kruskal–Wallis test showed significant differences between the intact and predrilled bones. Conclusion The pre-drilled bone was much weaker in both static and dynamic tests than the natural or implanted specimens. According to the results of the dynamic tests and after a certain loading cycle the implanted samples behaved the same way as the control samples, which suggests that implantation have stabilized the skeletal bone structure.

Assessment of changes in the biomechanical properties of the cornea after FemtoLASIK surgery

2021 ◽  
pp. 121-125
Author(s):  
E.V. Boiko ◽  
◽  
E.S. Togo ◽  
I.B. Litvin ◽  
A.B. Kachanov ◽  
...  
Keyword(s):  
Key Words ◽  
Refractive Surgery ◽  
Biomechanical Properties ◽  
Corvis St ◽  
Vision Correction ◽  
Before And After ◽  
Keratorefractive Surgery

Purpose. The aim of the study is to investigate the biomechanical properties of the cornea before and after FemtoLASIK in patients with myopia. Material and methods. 24 patients (42 eyes) underwent refractive vision correction using the FemtoLASIK method. The Oculus CORVIS ST ® device (Oculus, Germany) was used to assess the biomechanical properties of the cornea. Results. A statistically significant decrease in the rigidity and strength of the cornea was noted after keratorefractive surgery. Conclusion. Refractive surgery using FemtoLASIK technology leads to a decrease in the rigidity of the cornea, and therefore to a reduction in its framework properties. Key words: refractive surgery, FemtoLASIK, myopia, laser correction, biomechanical properties of the cornea, Oculus CORVIS ST ®.

scholarly journals In-plane Shear Strengthening of Unreinforced Masonry Walls Using GFRP Jacketing

2017 ◽  
Author(s):  
Enea Mustafaraj ◽  
Yavuz Yardim
Keyword(s):  
Experimental Results ◽  
Test Results ◽  
Compression Tests ◽  
Shear Strengthening ◽  
Plane Shear ◽  
Standard Size ◽  
Reinforced Polymer ◽  
Glass Fiber Reinforced ◽  
Diagonal Compression ◽  
Before And After

In this paper, it is presented the experimental results of a campaign on diagonal compression tests, as of ASTM E519-02, to assess and compare the in-plane behavior of standard size of 1200 × 1200 × 250 mm, for three unreinforced and three reinforced wall panels by glass fiber reinforced polymer (GFRP) embedded in an inorganic matrix.From the diagonal compression test results, were determined some of the main mechanical parameters such as: shear strength, modulus of rigidity and ductility, before and after application of the reinforcement.The experimental results showed that the GFRP reinforced panels exhibited a significant increase of 127% in shear resistance, 1100% in ductility and 650% in modulus of rigidity when compared to unreinforced panels.It was concluded that this technique provided satisfactory results and can be considered a suitable method for repair of masonry structures.

scholarly journals Is It Necessary to Reduce Thoracolumbar Compression Fractures  with Intermediate Screws in the Fractured Vertebra?

2021 ◽  
Author(s):  
ZeJun Xing ◽  
Shuai Hao ◽  
XiaoFei Wu
Keyword(s):  
Blood Loss ◽  
Body Height ◽  
Pedicle Screws ◽  
Operation Time ◽  
Short Segment ◽  
Compression Fractures ◽  
Significant Difference ◽  
Before And After ◽  
Screw Group

Abstract PurposeTo compare the efficacy and safety of percutaneous short-segment pedicle screws fixation (PPSF) with or without intermediate screws (IS) for the treatment of thoracolumbar compression fractures.MethodsFrom January 2016 to March 2019, a retrospective study of 38 patients with thoracolumbar compression fractures conducted. The patients were divided into a 4-screw group (without IS) and a 6-screw group (with IS) according to whether pedicle screws were placed in the fractured vertebrae. Combined positional reduction effects with the technique of pre-contoured lordotic rods were used to reduce the fracture by lengthening the anterior column of the fractured vertebrae. The posterior structure of the fractured vertebrae was undertaken as the fulcrum point for both groups. The operation time, intra-operative blood loss, visual analogue scale (VAS), anterior vertebral body height (AVBH), segment kyphosis（SK）before and after operation and complications were recorded.ResultsAlthough the operation time and blood loss in the 6-screw group were higher than in the 4-screw group, difference was not significant (P＞0.05). There was no significant difference in VAS, AVBH and SK between the two groups (P＞0.05). Nevertheless, these results were significant differences between the preoperative and the immediate postoperative, between preoperative and follow-up groups (P < 0.001). No neurologic injury was observed in either groups. ConclusionsIn the treatment of thoracolumbar compression fractures, percutaneous short-segment pedicle screws fixation without intermediate screws in the 4-screw construct may obtain the same clinical effect as that in the 6-screw construct.

scholarly journals The study of the microstructure of cheese before and after vacuum drying

2020 ◽  
Vol 10 (4) ◽  
pp. 6007-6014
Keyword(s):  
Calcium Phosphate ◽  
Surface Shape ◽  
Vacuum Drying ◽  
Protein Matrix ◽  
Fat Globules ◽  
Before And After ◽  
Calcium Phosphate Particles ◽  
Structure State ◽  
Cheese Microstructure ◽  
Scanning Electron

Scanning electron microscope allowed us to get screens of different cheese microstructure that form a base for further investigation of a cheese structure state before and after the process of drying and for their comparison. Any cheese structure presents a matrix of proteins penetrated with moisture capillaries; fat globules are located both inside the protein matrix and on a cheese surface. Shape of capillaries is either round or oval. Capillaries vary in size and number that has an impact on the cheese pattern which is described by hole and void shapes and order. Electron microscopy was also used for detecting deposition of calcium phosphate. Particles of calcium phosphate changed in size, before drying they were 10–12 µm, and after drying they reached 20–30 µ. These particles concentrate in the dried cheese and agglomerate into larger particles. The most concentrated calcium phosphate proportion was found in pores and micro-voids of the dry cheese. As for mature cheese samples, calcium lactate was established as well.

scholarly journals FEATURES OF THE DIAGNOSIS OF UNCOMPLICATED COMPRESSION FRACTURE OF THE THORACIC SPINE IN CHILDREN

2019 ◽  
Vol 20 (5) ◽  
pp. 307-311
Author(s):  
Yakhya M. Yakhyaev ◽  
M. I. Izrailov ◽  
V. N. Merkulov ◽  
A. M. Aliskandiev ◽  
T. Ya. Yakhyaeva
Keyword(s):  
Thoracic Spine ◽  
Compression Fracture ◽  
Diagnostic Process ◽  
Vertebral Compression Fractures ◽  
Thoracic Vertebrae ◽  
Healthy Children ◽  
X Ray ◽  
Compression Fractures ◽  
Fractures In Children ◽  
Ct And Mri

X-ray diagnostics of compression fractures of bodies of the thoracic vertebrae in children not seldom causes great difficulties due to the fact that even in healthy children vertebrae have a number of features, particularly, the wedge shape. For the purpose of differential diagnosis there was performed chest X-ray examination of the thoracic vertebrae in healthy children and cases after the compression damage. The wedge index and the disk coefficient for various segments of the thoracic spine were calculated. The diagnostic efficiency of radionuclide studies was estimated to reaches 79%. The useof highly informative modern medical techniques (CT and MRI) in the diagnosis of vertebral compression fractures in children allows accurately and timely make the diagnosis and determine the condition of the surrounding tissues. Based on the analysis of medical records, radiographs, identification of options of radionuclide, CT and MRI studies, there was elaborated an algorithm for the diagnosis of compression fractures of vertebrae, which allowed optimize the diagnostic process. There are determined advantages of this algorithm.

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