Finite element simulation and experimental test of normal coracoclavicular ligament and flexible reconstruction / 中国组织工程研究

BACKGROUND:For dislocation of acromioclavicular joint induced by coracoclavicular ligament fracture,single EndoButton Plate reconstruction and double EndoButton Plates reconstruction are common repair methods.Further study on the stress distribution and fracture risk of the two repair methods is of great significance. OBJECTIVE:To study the biomechanical properties of the coracoclavicular ligament,and compare the fixation effect,stress distribution and failure mode of single and double EndoButton Plates reconstruction. METHODS:(1)Finite element simulation analysis:Mimics,Wrap and SolidWorks were used to establish normal coracoclavicular ligament,single EndoButton Plate reconstruction and double EndoButton Plates reconstruction.Ansys software was used to analyze the stress and deformation of the scapula and clavicle of each model under vertical load.(2)Sample experiment:Fifteen intact scapular-clavicle specimens were randomly grouped into five groups,with three specimens in each group.In group A,the acromioclavicular ligament was severed and the coracoclavicular ligament remained intact.In group B,acromioclavicular ligaments and trapeoid ligaments were severed,leaving intact conical ligaments.In group C,acromioclavicular ligaments and conical ligaments were cut off,and the intact traprex ligaments were retained.In group D,acromioclavicular and coracoclavicular ligaments were severed,and coracoclavicular ligaments were repaired by single EndoButton Plate reconstruction.In group E,acromioclavicular and coracoclavicular ligaments were severed,and the coracoclavicular ligaments were repaired by double EndoButton Plates reconstruction.The mechanical experiment was carried out by a mechanical testing machine to analyze the biomechanical status,stress distribution and failure patterns of the scapular-clavicle and clavicle. RESULTS AND CONCLUSION:(1)Finite element simulation analysis:The average stress of coracoclavicular ligament attached specimens was the lowest,and the risk of coracoclavicular fracture was less than that of single and double EndoButton Plates reconstruction.The mean stress of the coracoid process was similar in single and double EndoButton Plates reconstruction,and the fracture risk was similar.(2)Sample experiment:In groups A,B,C,D and E,the stiffness of specimens was(26.4±3.5),(19.8±2.8),(21.3±3.2),(57.7±4.1),and(46.2±2.8)N/mm,respectively;the ultimate loads were(545.5±53.7),(360.1±42.1),(250.9±44.4),(643.5±39.1),and(511.9±31.7)N,respectively;global stiffness in groups D and E was higher than that in group A(P=0.000 06,0.000 3);ultimate load in group D was higher than that in group A(P<0.05);the ultimate load was not significantly different between the group E and group A(P>0.05).Ligament fracture was observed in groups A,B and C and coracoid process fracture was found in groups D and E.(3)These results suggest that from the biomechanical analysis,Single EndoButton Plate reconstruction and double EndoButton Plates reconstruction are effective treatment techniques for coracoclavicular ligament fracture in acromioclavicular joint dislocation,but increase the risk of fracture.The double EndoButton Plates reconstruction dispersed the stress of the steel plate and reduced the contact force between the steel plate and bone,but slightly reduced the ultimate bearing capacity.Single and double EndoButton Plates reconstruction should be selected according to the actual clinical situation.

Finite element and biomechanical analysis of different implants in repair for unilateral unstable pelvic posterior ring injury / 中国组织工程研究

BACKGROUND:The stability of the pelvis is mainly determined by the posterior pelvic ring and the sacroiliac joint.The posterior pelvic ring injury and the dislocation of the sacroiliac joint caused by high energy impacts such as car accidents increase year by year.Surgical treatment is the best method,and there are many kinds of endophytorepair methods in clinical practice,but which treatment method has the best biomechanical properties is still controversial. OBJECTIVE:To compare the biomechanical properties of three kinds of internal implants:anterior double plates,posterior bridging plate and tension nail in the repair of unilateral unstable pelvic posterior ring injury,to provide a reference for the clinical treatment and development of a new pelvic tension screw. METHODS:(1)Finite element simulation:Mimics,Wrap and SolidWorks were used to establish normal pelvic model,unilateral injured pelvis model,and three kinds of internal implant repaired models(anterior double plates,posterior bridging plate and tension nail).Ansys was used to analyze the stress and deformation of the models.(2)Biomechanical test:A total of 15 intact pelvic specimens were randomly grouped into five groups,normal pelvic model,unilateral injured pelvis model,anterior double plates,posterior bridging plate and tension nail groups.The mechanical test was performed using an Instron E10000 testing machine. RESULTS AND CONCLUSION:(1)Simulation:In the normal pelvic model,the average displacement of the sacrum was 0.174 mm,and the maximum stress of the sacral iliac bone was 10.51 MPa,and the stress distribution was uniform.The mean sacral displacement of the unilateral injured pelvis model was 0.267 mm,and the stress concentration of the model was obvious.The mean displacement of the sacrum in the three repaired models was close to that in the normal pelvic model,and the stress distribution of the sacral iliac bone in the tension nail repaired model was uniform.(2)Mechanical test:The stiffness of the normal pelvic model was(226.38±4.18)N/mm,and that of the unilateral unstable pelvic model was the smallest(130.02±2.19)N/mm.The deviation of the normal pelvic model stiffness and the three repaired models'stiffness were all within(±10%),and the repair effect was obvious.(3)The simulation results were in agreement with the experimental results.(4)The biomechanics of the tension nail repaired model was the most similar to that of the normal pelvis,and this method was the best.The repairing stiffness of the anterior double plate was too large,and the stress shielding effect was more significant.The posterior bridging plate repair could not solve the compensatory effect of the normal side soft tissue and had defects.This study provides an optimal basis for clinical surgery.(5)The new type of pelvic tension nail should be improved from the point of view of the tension nail to retain the good biomechanical properties of the tension nail,while adding other advantages,such as being used for the osteoporotic pelvis.

Antibacterial magnesium oxide-calcium phosphate composite coating prepared by combining electrodeposition and sol-gel impregnation / 中国组织工程研究

BACKGROUND:Calcium phosphate(CaP)coatings are widely used to improve the integration of titanium implants into bone but these coatings are associated with risks of infection.It is thus desirable to confer antibacterial properties to CaP coatings. OBJECTIVE:To prepare CaP-MgO composite coatings by impregnating magnesium oxide(MgO)sol into CaP coatings and assess the in vitro antibacterial activities and cytocompatibility. METHODS:An electrolyte was determined by titration and used for CaP coating electrodeposition on titanium(referred to as Ti-CaP).MgO was impregnated into the coating by immersing in an MgO sol with different mass fractions(15%,30%,50%)and subsequently calcined to form MgO-CaP composite coatings,which were recorded as Ti-CaP-15Mg,Ti-CaP-30Mg and Ti-CaP-50Mg,respectively.Microstructure,tensile properties,critical load,and Mg2+ release of coatings in vitro were characterized.Antibacterial activity was assayed using spread plate method by culturing S.aureus on the pure titanium sheet surface and Ti-CaP,Ti-Cap-15mg,Ti-Cap-30mg and Ti-Cap-50mg surfaces for 24 and 48 hours.Mouse osteoblast suspension was inoculated on pure titanium sheets and Ti-CaP,Ti-CaP-15Mg,Ti-CaP-30Mg and Ti-CaP-50Mg coated titanium sheets,respectively.Cell proliferation was detected by CCK-8 assay,and cell survival rate was calculated.The morphology of composite coating soaked in DMEM was also observed. RESULTS AND CONCLUSION:(1)Homogeneous,microporous CaP coatings consisting of octacaclium phosphate crystal flakes were prepared on titanium by electrodeposition.After sol impregnation-calcination,MgO aggregates were filled into the inter-flake voids.The extent of MgO filling and Mg concentration in the coating increased with the number of sol impregnation procedures.When immersed in phosphate buffered saline,all composite coatings actively released Mg2+ within 1 day;subsequently,the Mg2+ release slowed down on day 3.A small amount of Mg2+ release was still detected on day 7.The yield strength,tensile strength and fracture growth rate of Ti-CaP-30Mg coated titanium were not significantly different from those of pure titanium(P>0.05).There was no significant difference in the critical load of Ti-CaP,Ti-CaP-15Mg,Ti-CaP-30Mg and Ti-CaP-50Mg groups(P>0.05).(2)Except that pure titanium sheet and Ti-CaP had no antibacterial properties,the other samples had good antibacterial properties,and the antibacterial rate increased with the increase of MgO content in the coating.(3)After 1 and 3 days of co-culture,the cell survival rate of Ti-CaP-15Mg,Ti-CaP-30Mg and Ti-CaP-50Mg groups was lower than that of pure titanium group and Ti-CaP group(P<0.05).After 5 and 7 days of culture,there was no significant difference in cell survival rate among five groups(P>0.05).The content of MgO in the coating decreased gradually with the time of immersion in the medium.(4)The MgO sol impregnation added antibacterial properties to the CaP coatings while retained their biocompatibility.

Preparation and properties of a new artificial bone composite material / 中国修复重建外科杂志

OBJECTIVE@#To study the preparation and properties of the hyaluronic acid (HA)/α-calcium sulfate hemihydrate (α-CSH)/β-tricalcium phosphate (β-TCP) material (hereinafter referred to as composite material).@*METHODS@#Firstly, the α-CSH was prepared from calcium sulfate dihydrate by hydrothermal method, and the β-TCP was prepared by wet reaction of soluble calcium salt and phosphate. Secondly, the α-CSH and β-TCP were mixed in different proportions (10∶0, 9∶1, 8∶2, 7∶3, 5∶5, and 3∶7), and then mixed with HA solutions with concentrations of 0.1%, 0.25%, 0.5%, 1.0%, and 2.0%, respectively, at a liquid-solid ratio of 0.30 and 0.35 respectively to prepare HA/α-CSH/ β-TCP composite material. The α-CSH/β-TCP composite material prepared with α-CSH, β-TCP, and deionized water was used as the control. The composite material was analyzed by scanning electron microscope, X-ray diffraction analysis, initial/final setting time, degradation, compressive strength, dispersion, injectability, and cytotoxicity.@*RESULTS@#The HA/α-CSH/β-TCP composite material was prepared successfully. The composite material has rough surface, densely packed irregular block particles and strip particles, and microporous structures, with the pore size mainly between 5 and 15 μm. When the content of β-TCP increased, the initial/final setting time of composite material increased, the degradation rate decreased, and the compressive strength showed a trend of first increasing and then weakening; there were significant differences between the composite materials with different α-CSH/β-TCP proportion ( P<0.05). Adding HA improved the injectable property of the composite material, and it showed an increasing trend with the increase of concentration ( P<0.05), but it has no obvious effect on the setting time of composite material ( P>0.05). The cytotoxicity level of HA/α-CSH/β-TCP composite material ranged from 0 to 1, without cytotoxicity.@*CONCLUSION@#The HA/α-CSH/β-TCP composite materials have good biocompatibility. Theoretically, it can meet the clinical needs of bone defect repairing, and may be a new artificial bone material with potential clinical application prospect.

Clinicopathological features of very well-differentiated adenocarcinoma of the stomach / 中华病理学杂志

Objective: To investigate the clinicopathological features of very well-differentiated adenocarcinoma (VWDA) of the stomach. Methods: The clinicopathological data of 12 cases of VWDA of the stomach were collected retrospectively at the People's Liberation Army Joint Logistics Support Force 989 Hospital (formerly 152 Hospital), Pingdingshan, China, from January 2013 to May 2021. The histological characteristics and immunophenotypes were observed and analyzed with review of current literature. Results: There were 8 males and 4 females with a median age of 63 years (range 47 to 80 years). The tumor involved in the upper part of the stomach in 6 cases, the middle part in 2 cases, and the lower part in 4 cases. The median diameter of the tumors was 17 mm (range 5-65 mm). The tumor cells were similar to absorbent cells, Paneth cells, foveolar epithelial cells, and goblet cells. The cells were arranged in a single layer, and the nuclei were slightly enlarged and located at the base. The nuclei were fusiform to slightly irregular, with loss of nuclear polarity. Early tubular VWDA was found in 9 cases, and the tumor glands were similar to intestinal metaplasia. In two cases the tumors infiltrated into the submucosa. The lesions in the mucosa and submucosa showed the glands with cystic expansion, bending, branching, spiky and abortive growth pattern. One case of early papillary tubular VWDA was confined to the mucosal layer and composed of foveolar-type epithelial cells. There were two cases of advanced papillary tubular VWDA, which consisted of foveolar-type epithelial, pyloric glands, or mucinous neck cells and were associated with intra-lymphatic cancer embolus and lymph node metastases. Background mucosal atrophy and intestinal metaplasia were observed in all cases. Immunohistochemical staining showed intestinal type VWDA in 1 case, mixed gastrointestinal type VWDA in 9 cases, and gastric type VWDA in 2 cases. The Ki-67 proliferation index of 8 cases limited to the mucosa was 40%-70%, 2 cases of infiltration into the submucosa and 2 cases of advanced carcinoma was 10%-25%. All the tumors showed a wild type of p53 protein expression pattern and negative HER2. Adenocarcinoma or high-grade dysplasia was diagnosed on preoperative biopsy in 5 cases, and chronic atrophic gastritis with intestinal metaplasia in 7 cases. The median follow-up time was 28 months (range 12-72 months). No recurrence was found in the 10 patients with early cancer. Of the two patients with advanced carcinoma, one patient had lung metastases and the other died. Conclusions: Gastric VWDA is a rare low-grade malignancy with structural features of highly differentiated adenocarcinoma and extremely low cytological atypia. The diagnostic value of structural abnormality is significantly greater than cytological atypia. The invasive growth of irregular glands in the deep mucosa and submucosa is reliable evidence for diagnosis. The diagnosis of intramucosal VWDA is challenging and very difficult in some biopsy specimens.

Mechanics Analysis on Novel Micro-Movement Elastic Implant of Distal Tibiofibular Syndesmosis in Dorsiflexion Position / 医用生物力学

Objective To study mechanical properties of the novel micro-movement elastic implant of distal tibiofibular syndesmosis in dorsiflexion position.Methods A combination of simulation and experiment was used. The normal ankle dorsiflexion model, the bone nail repaired model and the micro-movement elastic implant repaired model were established by using Mimics and CT data. Besides, ANSYS Workbench was used for finite element analysis. Mechanical experiments on lower limb specimens were conducted on Instron E10000 mechanical test instrument, and five sets of experimental data were measured and analyzed.Results Mechanical properties of the micro-movement elastic implant repaired model were closer to those of the normal ankle dorsiflexion model, but stress of the micro-movement elastic implant repaired mode was greater than that of the bone nail repaired model. The results of two-sample heteroscedasticity t test indicated that there was no significant difference in resistance torque between the micro-movement elastic implant repaired model and the normal ankle dorsiflexion model.Conclusions For dorsiflexion position, repairing mechanical properties of the novel micro-movement elastic implant are much better than those of the bone nail, and there is still room for optimizing the micro-movement elastic implant.

Mechanical Properties of Novel Interlocking Intramedullary Nail for Fixing Transverse Olecranon Fractures / 医用生物力学

Objective To study the effect of interlocking intramedullary nail on fixing transverse olecranon fracture. Methods Nine pairs of fresh ulna specimens were collected and the transverse fracture model of olecranon was established. Kirschner wire tension band and interlocking intramedullary nail were used to repair the fracture. Cyclic dynamic tension loads with amplitude of 25 N, mean value of 45 N and frequency of 05 Hz were applied to the triceps tendon under simulated elbow flexion conditions of 30°, 45° and 60°, respectively. The fracture displacements of specimens within 300 cycles were recorded in three groups. ResultsAt 30° flexion angle, the fracture displacement of interlocking intramedullary nail group and Kirschner wire tension band group was (1.831±0.333) mm and (3.723±2.390) mm, respectively. At 45° flexion angle, the fracture displacement of interlocking intramedullary nail group and Kirschner wire tension band group was (1.167±0.374) mm and (2.455±0.609) mm, respectively. At 60° flexion angle, the fracture displacement of interlocking intramedullary nail group and Kirschner wire tension band group was (1.407±0.342) mm and (3.112±1.025) mm, respectively. The fracture displacement of interlocking intramedullary nail was smaller. Conclusions The mechanical properties of interlocking intramedullary nail are better than those of Kirschner wire tension band, and the interlocking intramedullary nail is more stable and firmer for fixing transverse olecranon fracture. Moreover, the interlocking intramedullary nail is installed with the operating tool, thus the operation is more accurate and faster, and the operation efficiency is greatly improved.

Axial Mechanical Properties of the Posterior Spinal Pedicle Fixation System / 医用生物力学

Objective To analyze factors that affect axial mechanical performance of the posterior pedicle fixation system. Methods The mechanical model for axial mechanical properties of the posterior pedicle fixation system was established to perform mechanical analysis. By referring to the Standard YY/T 0961-2014, tests on axial ejection force and axial clamping torque of JHL-I multi-axis components, JHL-I single-axis components, JHL-V multi-axis components and JHL-V single-axis components were performed by using Instron E3000 and Instron E10000 mechanical testing machines. Results The ejection rigidity of the single-axis component of vertebral nail system was significantly higher than that of the multi-axis component of vertebral nail system; the torsion rigidity of JHL-V was higher than that of JHL-I. The type and size of the locking bolt as well as its locking torque were the main factors affecting axial ejection force of the posterior spinal pedicle fixation system; the size of the locking bolt and the diameter of the connection rod were the main factors affecting axial clamping torque of the system; axial mechanical properties of the system could be improved by increasing the diameter of the connecting rod, the coefficient of friction between each connecting element, and the pitch diameter of the locking bolt. Conclusions The research findings provide references for optimizing and improving axial mechanical properties of the posterior pedicle fixation system.

Introduction of intervention programs on cyberbullying abroad / 中国学校卫生

Abstract@#With the growing popularity of electronic devices, cyberbullying has gradually become a common form of bullying. Compared with traditional bullying, cyberbullying is more likely to cause serious psychological problems of its victims, leading to school absences, depression, even selfinflicted injury and suicide. Unfortunately, psychological intervention and prevention for cyberbullying and cyber victimization is rather sparse in China. This paper summarizes some foreign cyberbullying intervention projects, aiming at providing reference localized and specific interventions.

Inhibitory effects of Pin1 silencing by siRNA on apoptosis of H9c2 cardiomyo-cytes induced by hypoxia/reoxygenation / 中国免疫学杂志

Objective:Pin1 plays an important role in the pathogenesis of cardiovascular disease,our study aims to investigate the effects of Pin1 silencing by siRNA on H9c2 apoptosis induced by hypoxia/reoxygenation.Methods:H9c2 cells were cultured and subjected to a hypoxia/reoxygenation (H/R) condition in vitro,mimicking ischemic/reperfusion injury in vivo.The mRNA and protein expression of Pin1 were detected by RT-qPCR and Western blot.H9c2 cells were divided into control group,H/R group,H/R+Pin1 siRNA group,H/R+scramble siRNA group.MTT and flow cytometry with Annexin V-FITC/PI staining were respectively performed to detect cell viability and apoptosis.The expression of Bax and Bcl-2 were measured by Western blot.The activity of Caspase-3 was detected by automatic biochemistry analytic instrument.Results:The mRNA and protein levels of Pin1 were highly expressed in the cells of H/R group.Transfection with Pin1 siRNA strikingly inhibited the expression of Pin1.Compared with H/R group,Pin1 siRNA markedly increased cell viability,decreased the cell apoptosis and the Caspase-3 activity.Furthermore,the increased Bcl-2,decreased Bax and the ratio of Bcl-2 to Bax were observed in Pin1 siRNA group (P<0.05) compared with H/R group.Conclusion:Downregulation of Pin1 protects hypoxia/reoxygenation-injured H9c2 cells from apoptosis,which is possibly through the upregulation of Bcl-2 and downregulation of Bax and Caspase-3 activity.

[Coal Combustion Reactivity of Different Metamorphic Degree and Structure Changes of FTIR Analysis in Pyrolysis Process].

The combustion reaction of raw coals in the air was analyzed withThermal Gravimetric Analyzer 6300 and FTIR (Fourier Transform infrared spectroscopy). The raw coals came from three different sources which were SL lignite, SH bitumite and TT anthracite. The chars were prepared by fixed bed pyrolysis equipment in different reaction temperature. The overlapping peaks were fitted into some sub-peaks by Gaussian function. The aromatic index (R), aromatic structure fused index (D) and organic maturity index (C) were calculated through sub-peaks areas. It showed that three kinds of ignition temperature of SL, SH and TT were 299.3, 408.2 and 441.0 ℃ respectively. The peak temperature of maximum weight loss rate were 348.6, 480.5 and 507.0 ℃ respectively. With the increase of coal rank, both ignition temperature and peak temperature of maximum weight loss rate increased in some degree. The result showed that coal structure was very complex. Vibration absorption peaks of hydroxyl (­OH), aliphatic hydrocarbons (­CH2，­CH3), aromatic (CC), oxygen-containing functional group(CO, C­O) and other major functional groups could be observed in the infrared spectral curves of all samples. With the increase of pyrolysis temperature, infrared vibration absorption peaks of aliphatic hydrocarbons (­CH2­, ­CH3) were gradually decreased. the stretching vibration peak of CO which was at 1 700 cm-1 almost disappeared after coked at 550 ℃. SL samples' absorption peak area infrared curve of oxygen functional groups at 1 000～1 800 cm-1 was more complex. With the increase of coking temperature they changed more significantly compared with others. While peak position and peak intensity for aromatic CC absorption peaks of SH and TT did not change apparently when temperature was changing. Variation trends of main functional groups among three ranks of coals were obviously different with changes of R, D and C values.