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Objective:To determine the mechanical properties of our self-designed novel cross-locking intramedullary nails and the impact of number of conical locking nails on the fixation through a finite element analysis and specimen experiments.Methods:Mimics 19.0 and SolidWorks 2014 were used to create transverse fracture models of the olecranon which were subjected to fixation with respectively K-wire tension band (KTB) and our self-designed novel cross-locking intramedullary nails (NIN). The strengths of KTB and NIN fixation were analyzed by Ansys. Fifteen human ulna specimens were used to construct a transverse fracture model of the olecranon; an Instron E10000 mechanical testing machine was used to determine mechanical properties in fixation respectively with KTB, one NIN (NIN-1) and 3 NINs (NIN-3).Results:In the finite element analysis, in simulation of the forearm flexed at 45° under a 100 N load, the deformation of the fracture surface of the olecranon in fixation with KTB, NIN-1 and NIN-3 was respectively 0.131 mm, 0.123 mm and 0.121 mm. In the specimen experiments, in simulation of the forearm flexed at 45°, the maximum failure loads for fixation with KTB, NIN-1 and NIN-3 were (313.38±27.68) N, (528.56±53.58) N and (871.04±94.95) N, respectively, showing significant differences among the 3 groups ( P<0.05). The maximum failure load for NIN-3 fixation was significantly greater than that for KTB or NIN-1 fixation, and the maximum failure load for NIN-1 fixation was significantly greater than that for KTB fixation ( P<0.05). Conclusions:Compared with KTB fixation, NIN fixation is more convenient in operation and has better mechanical properties. NIN-3 fixation has the best mechanical properties.
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Objective To test the validity for mechanical equation of the TC4 self-tapping bone screw and analyze the influence of bone screw parameters on its mechanical properties. Methods In order to derive the equation of self-tapping and pull-out for bone screw, the physical model of bone screw-polyurethane foam block was built. By reference of ASTMF543-07 standard specification and test method for metallic medical bone screw, the mechanical verification tests of selected conical head shallow thread locking bone screw (HAZ) and conical head deep thread locking bone screw (HBZ) with different diameters were performed on Instron E3000 mechanical testing machine, and the data of self-tapping force, self-tapping torque and pull-out force from 5 groups of bone screws were tested respectively. Results The calculated and measured values were basically the same, except for a few points with large individual errors. The average error of the two values was 11.02%, so the theoretical calculation formula was highly credible. The bone screw with a larger diameter or a higher tooth height would require greater self-tapping force and pull-out force. Conclusions The research results provide the calculation basis for mechanical properties of bone screw and the research direction for optimization and improvement of bone screw in future.
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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.
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Objective Random allocation concealment is important in ensuring high-guality randomized controlled clinical trial.In this paper , we aimed to design a more convenient and effective two couplet random allocation method through improving the random allocation concealment technology which uses the envelope method . Methods According to the randomized sequence , a two-couplet random allocation should be prepared for every subject and bound into a book in order , which named random assignment book with cover and instructions .The first couplet is to collect the enroll information and the second couplet is to show the allocation informa -tion.The serial numbers of the two couplets which around sealant are the same , and leave blank at the same areas of the two couplets for signing the enter information .The content of the first couplet can be completely copied to the second couplet .In order to avoid expo-sing the allocation information in advance , the back of the second couplet should be black-printed. When the subjects are sure qualified, the researchers selected the corresponding two couplet in a sequential order .Exposing the allocation infromation in the second couplet, and the subjects will be allocated to the group designated on the second couplet .This random allocation book should be entrusted to professional printing mechanism ,printing according to the random assignment sequence table and in the strict quality control .For the multicenter clinical trials , it can be printed in parts . Results The method has been implemented in nearly ten randomized controlled trials and obtained the consistent high praise . Conclusion The random allocation book method is easy to produce , simple operation and convenient in monitoring , which can effectively achieve the random allocation concealment in a clinical trial as well as having a sig -nificantly practical value in ensuring the quality of randomization .
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Objective To investigate the sleep quality state of people who did physical examination,and its correlation with brachial-ankle Pulse Wave Velocity (baPWV).Methods The indexes of Pittsburgh sleep quality index (PSQI) and baPWV were used.The people who did physical examination were divided into sleep disorders group (284 cases) and normal sleep group (608 cases) according to the results of PSQI survey.Results (1) There were 31.84％ of the people who had sleep quality problems.(2) The PSQI total score and the score of subjective sleep quality (SSQ),sleep duration (Sdu),daytime dysfunction (DD) of females were higher than males (t =6.71,3.46,2.45,3.96,P ＜0.05).The PSQI total score and the score of sleep latency (SL),habitual sleep efficiency (HSE),use of sleeping medication (USM) among different age groups were statistically analyzed (F =12.23,8.31,7.50,7.11,P ＜ 0.05).(3) The score of baPWV of sleep disorders group was higher than normal sleep group (t =5.14,P ＜ 0.05).There were significantly positive correlation between baPWV and total PSQI score,subjective sleep quality,sleep time,daytime dysfunction (r =0.28,0.45,0.30,0.36,0.35,P ＜ 0.05).Conclusions 1/3 of the physical examination people have sleep quality problems.Sleep quality of females is worse than males.There are different styles among different age groups.There is significantly positive correlation between sleep quality and baPWV.
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Safety assessment in clinical trials is dependent on an in-depth analysis of the adverse events to a great extent. However, there are difficulties in summary classification, data management and statistical analysis of the adverse events because of the different expressions on the same adverse events caused by regional, linguistic, ethnic, cultural and other differences. In order to ensure the normative expressions, it's necessary to standardize the terms in recording the adverse events. MedDRA (medical dictionary for regulatory activities) has been widely recommended and applied in the world as a powerful support for the adverse events reporting in clinical trials. In this paper, the development history, applicable scope, hierarchy structure, encoding term selection and standardized query strategies of the MedDRA is introduced. Furthermore, the practical process of adverse events encoding with MedDRA is proposed. Finally, the framework of statistical analysis about adverse events is discussed.
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The Bland-Altman method has been widely used for consistency evaluation in the field of medicine .However, fre-quent errors in the application of the method seriously affect the quality of researches .This review focuses on the studies of the Bland-Altman method , the status quo and common problems in its application , and standards for related reports .