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Journal of Renewable Materials 2023年第12期11卷 4175-4195页

作者： Huifeng Yang Mingwang Wu Rixin Gu Hang Cao Kai Xiao Benkai Shi College of Civil Engineering Nanjing Tech UniversityNanjing211816China

This article presents experimental results of steel-timber-steel(STS)joints loaded parallel to grain.Eight groups of specimens were designed,and tensile tests were performed.The fastener types and fastener numbers were considered to evaluate the tensile strengths and ductility performances of the STS joints.The screws with 6 mm diameter and the innovative steel-tubes with 18 mm diameter were adopted as connecting fasteners.The experimental results were discussed in terms of yielding and ultimate strengths,slip stiffness,and ductility factors.The ductility classification and failure mechanisms of each group of specimens were analyzed.It was demonstrated that the STS joint with large diameter steel-tubes showed acceptable ductility,which was close to the ductility of the STS joint with small diameter screws,thanks to the hollow structure of the steel-tube.The theoretical strengths of various failure modes for the joints with small diameter screws or large diameter steel-tubes were calculated and compared with the experimental results.The ductile performance of the STS joint was discussed by comparing the theoretical strengths of various failure modes.The effective number of the STS joint with multifasteners was also analyzed by considering the failure mechanisms in aspects of tensile strength and slip stiffness.

关键词： Steel-timber-steel joint screw steel-tube ductility experimental investigation timber structure

screw placement is everything: Risk factors for loss of reduction with volar locking distal radius plates

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World Journal of Orthopedics 2018年第10期9卷 203-209页

作者： Herwig Drobetz Alyce Black Jonathan Davies Petra Buttner Clare Heal James Cook University School of Medicine and Dentistry Mackay Institute of Research and Innovation Mackay Hospital Mackay Base Hospital Orthopaedic Department Mackay Hospital Tropical Health Solutions PTY Ltd Centre for Chronic Disease Prevention James Cook University Anton Breinl Research Centre for Health Systems Strengthening

AIM To determine factors correlated with postoperative radial shortening in patients with distal radius fractures treated with volar locking distal radius plates.METHODS A total of 250 patients with a distal radius fracture stabilised with volar locking plates between January 2010 and December 2014 were included in a multicentre retrospective cohort study. We measured the distance of the distal locking screws to the joint line immediately postoperatively and then measured radial shortening after six to eight weeks using the change in ulnar variance.RESULTS Multivariate linear regression analysis showed that there was a significant linear association between the distance of the screws from the joint line and radial shortening. No other patient, injury, or treatment-related characteristic significantly influenced radial shortening in multivariate analysis.CONCLUSION Distal locking screws should be placed as close as possible to the subchondral joint line to prevent postoperative loss of reduction.

关键词： Loss of reduction Volar locking distal radius plate Distal radius fracture screw placement Cohort study

Effect of surgical factors on the augmentation of cementinjectable cannulated pedicle screw fixation by a novel calcium phosphate-based nanocomposite

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Frontiers of Medicine 2019年第5期13卷 590-601页

作者： Haolin Sun Chun Liu Shunlun Chen Yanjie Bai Huilin Yang Chunde Li Lei Yang Department of Orthopedics Peking University First Hospital Beijing 100034China Orthopedic Institute Department of OrthopedicsFirst Affiliated HospitalSoochow UniversitySuzhou 215006China School of Public Health Medical CollegeSoochow UniversitySuzhou 215100China International Research Center for Translational Orthopedics Suzhou 215006China School of Materials Science and Engineering Hebei University of TechnologyTianjin 300130China

Bone cement-augmented pedicle screw system demonstrates great efficacy in spinal disease treatments. However, the intrinsic drawbacks associated with clinically used polymethylmethacrylate (PMMA) cement demands for new bone cement formulations. On the basis of our previous studies, a novel injectable and biodegradable calcium phosphate-based nanocomposite (CPN) for the augmentation of pedicle screw fixation was systematically evaluated for its surgical feasibility and biomechanical performance by simulated and animal osteoporotic bone models, and the results were compared with those of clinical PMMA cement. ASTM-standard solid foam and open-cell foam models and decalcified sheep vertebra models were employed to evaluate the augmentation effects of CPN on bone tissue and on the cement-injected cannulated pedicle screws (CICPs) placed in osteoporotic bone. Surgical factors in CICPs application, such as injection force, tapping technique, screw diameter, and pedicle screw loosening scenarios, were studied in comparison with those in PMMA. When directly injected to the solid foam model, CPN revealed an identical augmentation effect to that of PMMA, as shown by the similar compressive strengths (0.73 ± 0.04 MPa for CPN group vs. 0.79 ± 0.02 MPa for PMMA group). The average injection force of CPN at approximately 40-50 N was higher than that of PMMA at approximately 20 N. Although both values are acceptable to surgeons, CPN revealed a more consistent injection force pattern than did PMMA. The dispersing and anti-pullout ability of CPN were not affected by the surgical factors of tapping technique and screw diameter. The axial pullout strength of CPN evaluated by the decalcified sheep vertebra model revealed a similar augmentation level as that of PMMA (1351.6 ± 324.2 N for CPN vs. 1459.7 ± 304.4 N for PMMA). The promising results of CPN clearly suggest its potential for replacing PMMA in CICPs augmentation application and the benefits of further study and development for clinical uses.

关键词： bone cement pedicle screw degenerative spinal diseases calcium phosphate injectable

Computer navigation-assisted minimally invasive percutaneous screw placement for pelvic fractures

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World Journal of Clinical Cases 2020年第12期8卷 2464-2472页

作者： Tong Yu Xue-Liang Cheng Yang Qu Rong-Peng Dong Ming-Yang Kang Jian-Wu Zhao Department of Orthopedics the Second Hospital of Jilin UniversityChangchun 130014Jilin ProvinceChina

Pelvic fractures are often caused by high-energy injuries and accompanied by hemodynamic instability.Traditional open surgery has a large amount of bleeding,which is not suitable for patients with acute pelvic fracture.Navigationguided,percutaneous puncture-screw implantation has gradually become a preferred procedure due to its advantages,which include less trauma,faster recovery times,and less bleeding.However,due to the complexity of pelvic anatomy,doctors often encounter some problems when using navigation to treat pelvic fractures.This article reviews the indications,contraindications,surgical procedures,and related complications of this procedure for the treatment of sacral fractures,sacroiliac joint injuries,pelvic ring injuries,and acetabular fractures.We also analyze the causes of inaccurate screw placement.Percutaneous screw placement under navigational guidance has the advantages of high accuracy,low incidence of complications and small soft-tissue damage,minimal blood loss,short hospital stays,and quick recovery.There is no difference in the incidence of complications between surgeries performed by new doctors and experienced ones.However,computer navigation technology requires extensive training,and attention should be given to avoid complications such as screw misplacement,intestinal injury,and serious blood vessel and nerve injuries caused by navigational drift.

关键词： Computer navigation Percutaneous puncture screw Pelvic fracture Sacral fracture Acetabular fracture Iliac fracture Pubic fracture

Geometric error analysis of an over-constrained parallel tracking mechanism using the screw theory

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Chinese Journal of Aeronautics 2019年第6期32卷 1541-1554页

作者： Jiateng ZHANG Binbin LIAN Yimin SONG Key Laboratory of Mechanism Theory and Equipment Design of Ministry of Education Tianjin UniversityTianjin 300072China Department of Machine Design KTH Royal Institute of TechnologyStockholm SE-10044Sweden

This paper deals with geometric error modeling and sensitivity analysis of an overconstrained parallel tracking mechanism. The main contribution is the consideration of overconstrained features that are usually ignored in previous research. The reciprocal property between a motion and a force is applied to tackle this problem in the framework of the screw theory. First of all, a nominal kinematic model of the parallel tracking mechanism is formulated. On this basis, the actual twist of the moving platform is computed through the superposition of the joint twist and geometric errors. The actuation and constrained wrenches of each limb are applied to exclude the joint displacement. After eliminating repeated errors brought by the multiplication of wrenches, a geometric error model of the parallel tracking mechanism is built. Furthermore,two sensitivity indices are defined to select essential geometric errors for future kinematic calibration. Finally, the geometric error model with minimum geometric errors is verified by simulation with SolidWorks software. Two typical poses of the parallel tracking mechanism are selected, and the differences between simulation and calculation results are very small. The results confirm the correctness and accuracy of the geometric error modeling method for over-constrained parallel mechanisms.

关键词： Error model simulation Geometric error modeling Over-constrained parallel mechanism screw theory Sensitivity analysis

Numerical simulation of particle flow behavior in a screw conveyor using the discrete element method

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Particuology 2019年第2期17卷 137-148页

作者： Shuyan Wang Haolong Li Ruichao Tian Ruichen Wang Xu Wang Qiji Sun jiawei Fan School of Petroleum Engineering Northeast Petroleum University Daqing 163318 China

Particle motion in a screw conveyor was simulated w让h the discrete element method. The particle flow behavior and transport processes at different screw rotating speeds and filling levels were investigated in this study. The spatial distributions of particle velocity were predicted. The predicted mass flow rate increased w让h increasing screw rotating speed and filling level. The contact forces and granular temperatures of particles were also calculated. The simulation results showed that the translational granular particle temperatures were higher than the rotational granular particle temperatures. In add让ion, the configurational temperatures of particles were calculated from simulated instantaneous particle overlaps, and results indicated that deformation of elastic particles contributed to the rate of energy dissipation. Good agreement between the numerical simulation and experimental results was achieved in this study.

关键词： screw conveyor Discrete element method Granular temperature Simulation

Accuracy of pedicle screw placement in the thoracic and lumbosacral spines using O-arm-based navigation versus conventional freehand technique

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Chinese Neurosurgical Journal 2019年第3期5卷 137-143页

作者： Linkai Jing Zhenze Wang Zhenxing Sun Huifang Zhang James Wang Guihuai Wang School of Clinical Medicine Tsinghua UniversityBeijing 100084China Department of Neurosurgery Beijing Tsinghua Changgung HospitalSchool of Clinical MedicineTsinghua UniversityBeijing 102218China

The accuracy and safety of pedicle screw insertion was markedly improved with the introduction of intraoperative three-dimensional navigation system during the last decade. This study aimed to evaluate the accuracy of pedicle screw placement using O-arm-based navigation system versus conventional freehand technique. Methods: We reviewed the accuracy of 341 thoracic (n = 173) and lumbosacral (n = 168) pedicle screws placed in 60 consecutive patients using either O-arm-based navigation or freehand technique in the Department of Neurosurgery of Beijing Tsinghua Changgung Hospital between January 2015 and June 2018. Patient-specific characteristics, treatment-related characteristics, and screw-specific accuracy were analyzed. The accuracy of pedicle screw placement was measured by Gertzbein-Robbins scale and screw grades A and B were clinically acceptable. Results: One hundred ninety-one screws were inserted in the O-arm-based navigation group and 150 in the freehand group. One hundred eighty-three (95.81%) clinically acceptable screws were placed in the navigation group and 135 (90.00%) in the freehand group (p = 0.034). Twenty-three (6.74%) screw revisions were performed in the two groups (8 screws in the navigation group and 15 screws in the freehand group) and significant difference was observed in thoracic spine (p = 0.018), while no statistical significance was presented in lumbosacral spine (p >0.05). Twenty-four (12.57%) screws in the navigation group and 24 (16.00%) in the freehand group violated the cortex (p > 0.05). Medial screw deviation was the most common problem in the two groups. Conclusion: The O-arm-based navigation exhibits higher accuracy for pedicle screw insertion than the freehand insertion technique.

关键词： Accuracy Freehand Navigation O-arm Pedicle screw

Influence of velocity on the transmission precision of the ball screw mechanism

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High Technology Letters 2020年第2期26卷 217-223页

作者：孔德顺 Institute of Standard Metrology China Academy of Railway Sciences Corporation LimtedBeijing 100081P.R.China Beijing Huaheng Technology Co.Ltd. Beijing 100081P.R.China

Ball screw mechanism(BSM)is an important force-motion transfer device which is used in high-precision machine tools such as the computer numerical control.Performance parameters such as contact angle,helix angle,and the pitch radius of the screw can greatly affect the transmission precision,and the transmission precision of the BSM are not yet well resolved.In this study,ball contact point motion model is derived to assess the influence of contact angle,helix angle,and the pitch radius of the screw on transmission precision under uniform motion of the BSM.For the purpose of verifying the kinematic characteristics of the contact points between the balls and raceways under a state of uniform motion,a kinematic model is developed and values are computed for a set of boundary conditions.Comparing the simulated data to measured data,the laws of motion for the ball contact points developed in this study are confirmed.Moreover,the effect of the screw velocity on contact angle,helix angle and the pitch radius of the screw directly affects the velocity of the nut.Under the accelerated and uniform motion state of the screw,larger angular velocity of the screw results in an increase in the displacement deviation of the nut,and these parameters of the nut are considered to improve the transmission precision of the BSM.The verification of the research results provides a new research method for the study of the precision retention of ball screw mechanism.

关键词： ball screw mechanism(BSM) uniform motion structural parameters transmission precision

Laminar screw fixation in the subaxial cervical spine: A report on three cases

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World Journal of Orthopedics 2016年第10期7卷 695-699页

作者： Hironori Tanabe Yoichi Aota Tomoyuki Saito Department of Orthopedic Surgery Yokohama City University Department of Orthopedic Surgery Yokohama Stroke and Brain Center

Although laminar screw fixation is often used at the C2 and C7 levels, only few previous case reports have presented the use of laminar screws at the C3-C6 levels. Here, we report a novel fixation method involving the use of practical laminar screws in the subaxial spine. We used laminar screws in the subaxial cervical spine in two cases to prevent vertebral artery injury and in one case to minimize exposure of the lamina. This laminar screw technique was successful in all three cases with adequate spinal rigidity, which was achieved without complications. The use of laminar screws in the subaxial cervical spine is a useful option for posterior fusion of the cervical spine.

关键词： Laminar screw Instrumentation Subaxial cervical spine

Modern posterior screw techniques in the pediatric cervical spine

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World Journal of Orthopedics 2014年第2期5卷 94-99页

作者： Daniel J Hedequist Department of Orthopedic Surgery Children’s Hospital Boston/Harvard Medical School Boston MA 02115 United States

Treatment of children with cervical spine disorders requiring fusion is a challenging endeavor for a variety of reasons. The size of the patients, the corresponding abnormal bony anatomy, the inherent ligamentous laxity of children, and the relative rarity of the disorders all play a part in difficulty of treatment. The benefits of modern posterior cervical instrumentation in children, defined as rigid screw–rod systems, have been shown to be many including: improved arthrodesis rates, diminished times in halo-vest immobilization, and improved reduction of deformities. The anatomy of children and the corresponding pathology seen frequently is at the upper cervical spine and craniocervical junction given the relatively large head size of children and the horizontal facets at these regions predisposing them to instability or deformity. Posterior screw fixation, while challenging, allows for a rigid base to allow for fusion in these upper cervical areas which are predisposed to pseudarthrosis with non-rigid fixation. A thorough understanding of the anatomy of the cervical spine, the morphology of the cervical spine, and the available screw options is paramount for placing posterior cervical screws in children. The purpose of this review is to discuss both the anatomical and clinical descriptions re-lated to posterior screw placement in the cervical spine in children.

关键词： Pediatric cervical spine Cervical screw fixation Posterior cervical techniques