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基于改进Double-Head RCNN的无人机航拍图像小目标检测算法 被引量:1
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作者 王殿伟 胡里晨 +1 位作者 房杰 许志杰 《北京航空航天大学学报》 EI CAS CSCD 北大核心 2024年第7期2141-2149,共9页
为解决无人机航拍图像中小目标特征信息少且容易被噪声干扰导致现有算法漏检率和误检率高的问题,提出一种改进Double-Head Region-卷积神经网络(RCNN)的无人机航拍图像小目标检测算法。在骨干网络ResNet-50上引入Transformer和可变形卷... 为解决无人机航拍图像中小目标特征信息少且容易被噪声干扰导致现有算法漏检率和误检率高的问题,提出一种改进Double-Head Region-卷积神经网络(RCNN)的无人机航拍图像小目标检测算法。在骨干网络ResNet-50上引入Transformer和可变形卷积(DCN)模块,更有效提取小目标特征信息和语义信息;提出一种基于内容感知特征重组(CARAFE)的特征金字塔网络(FPN)结构模块,解决特征融合过程中小目标被背景噪声干扰而丢失特征信息的问题;在区域建议网络中针对小目标尺度分布特点重新设置Anchor生成尺度,进一步提升小目标检测性能。在VisDrone-DET2021数据集上的实验结果表明:所提算法能提取更具有表征能力的小目标特征信息和语义信息,对比Double-Head RCNN算法,所提算法的参数量增加了9.73×10^(6),FPS损失了0.6,但是AP、AP50和AP75分别提升了2.6%、6.2%和2.1%,APs提升了3.1%。 展开更多
关键词 小目标检测 无人机航拍图像 double-head RCNN TRANSFORMER 内容感知特征重组
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Additive manufactured osseointegrated screws with hierarchical design
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作者 Wenbo Yang Hao Chen +6 位作者 Haotian Bai Yifu Sun Aobo Zhang Yang Liu Yuchao Song Qing Han Jincheng Wang 《Bio-Design and Manufacturing》 SCIE EI CAS CSCD 2024年第2期206-235,共30页
Bone screws are devices used to fix implants or bones to bones.However,conventional screws are mechanically fixed with thread and often face long-term failure due to poor osseointegration.To improve osseointegration,s... Bone screws are devices used to fix implants or bones to bones.However,conventional screws are mechanically fixed with thread and often face long-term failure due to poor osseointegration.To improve osseointegration,screws are evolving from solid and smooth to porous and rough.Additive manufacturing(AM)offers a high degree of manufacturing freedom,enabling the preparation of predesigned screws that are porous and rough.This paper provides an overview of the problems currently faced by bone screws:long-term loosening and screw breakage.Next,advances in osseointegrated screws are summarized hierarchically(sub-micro,micro,and macro).At the sub-microscale level,we describe surface-modification techniques for enhancing osseointegration.At the micro level,we summarize the micro-design parameters that affect the mechanical and biological properties of porous osseointegrated screws,including porosity,pore size,and pore shape.In addition,we highlight three promising pore shapes:triply periodic minimal surface,auxetic structure with negative Poisson ratio,and the Voronoi structure.At the macro level,we outline the strategies of graded design,gradient design,and topology optimization design to improve the mechanical strength of porous osseointegrated screws.Simultaneously,this paper outlines advances in AM technology for enhancing the mechanical properties of porous osseointegrated screws.AM osseointegrated screws with hierarchical design are expected to provide excellent long-term fixation and the required mechanical strength. 展开更多
关键词 Bone screws Additive manufacturing Architecture design Surface modification
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Biomechanical effects of posterior lumbar interbody fusion with vertical placement of pedicle screws compared to traditional placement
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作者 Ji-Hong Jiang Chang-Ming Zhao +2 位作者 Jun Zhang Rong-Ming Xu Lei Chen 《World Journal of Clinical Cases》 SCIE 2024年第20期4108-4120,共13页
BACKGROUND The pedicle screw technique is widely employed for vertebral body fixation in the treatment of spinal disorders.However,traditional screw placement methods require the dissection of paraspinal muscles and t... BACKGROUND The pedicle screw technique is widely employed for vertebral body fixation in the treatment of spinal disorders.However,traditional screw placement methods require the dissection of paraspinal muscles and the insertion of pedicle screws at specific transverse section angles(TSA).Larger TSA angles require more force to pull the muscle tissue,which can increase the risk of surgical trauma and ischemic injury to the lumbar muscles.AIM To study the feasibility of zero-degree TSA vertical pedicle screw technique in the lumbosacral segment.METHODS Finite element models of vertebral bodies and pedicle screw-rod systems were established for the L4-S1 spinal segments.A standard axial load of 500 N and a rotational torque of 10 N/m were applied.Simulated screw pull-out experiment was conducted to observe pedicle screw resistance to pull-out,maximum stress,load-displacement ratio,maximum stress in vertebral bodies,load-displacement ratio in vertebral bodies,and the stress distribution in pedicle screws and vertebral bodies.Differences between the 0-degree and 17-degree TSA were compared.RESULTS At 0-degree TSA,the screw pull-out force decreased by 11.35%compared to that at 17-degree TSA(P<0.05).At 0-degree and 17-degree TSA,the stress range in the screw-rod system was 335.1-657.5 MPa and 242.8-648.5 MPa,separately,which were below the fracture threshold for the screw-rod system(924 MPa).At 0-degree and 17-degree TSA,the stress range in the vertebral bodies was 68.45-78.91 MPa and 39.08-72.73 MPa,separately,which were below the typical bone yield stress range for vertebral bodies(110-125 MPa).At 0-degree TSA,the load-displacement ratio for the vertebral bodies and pedicle screws was slightly lower compared to that at 17-degree TSA,indicating slightly lower stability(P<0.05).CONCLUSION The safety and stability of 0-degree TSA are slightly lower,but the risks of screw-rod system fracture,vertebral body fracture,and rupture are within acceptable limits. 展开更多
关键词 Vertical pedicle screw Pedicle screw technique Transverse section angle Lumbosacral segment Finite element analysis
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Revised in-depth meta-analysis on the efficacy of robot-assisted versus traditional free-hand pedicle screw insertion
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作者 Sorayouth Chumnanvej Branesh M.Pillai +1 位作者 Jackrit Suthakorn Siriluk Chumnanvej 《Laparoscopic, Endoscopic and Robotic Surgery》 2024年第4期155-165,共11页
Objective:Robot-assisted pedicle screw insertion has recently emerged as an alternative to the traditional free-hand technique.However,discrepancies in the accuracy of screw placement between the 2 methods have been h... Objective:Robot-assisted pedicle screw insertion has recently emerged as an alternative to the traditional free-hand technique.However,discrepancies in the accuracy of screw placement between the 2 methods have been highlighted by some comparative studies.This meta-analysis was conducted to synthesize evidence comparing these techniques.Methods:Searches were conducted in 5 electronic databases adhering to specific eligibility criteria for randomized and observational studies.The data were analyzed using RevMan software and the results are presented as odds ratios(ORs),mean differences,or standard mean differences(SMDs)with 95%confidence intervals(CIs).Our analysis included 12 studies(7 randomized trials and 5 observational studies,involving 883 patients and 4903 screws).Results:The results demonstrated a higher rate of Grade A Gertzbein and Robbins pedicle placement score(OR:1.77;95%CI:1.10e2.87),a lower rate of revision surgeries(OR:0.21;95%CI:0.09e0.52),and a shorter radiation exposure duration(SMD?1.38,95%CI:2.32 to0.44)in the robot-assisted group compared with the free-hand group.Nonetheless,the length of hospital stay,volume of intraoperative blood loss,postoperative visual analogue scale scores for back pain,and rate of wound infection were similar between the 2 groups.Significant heterogeneity was observed in some outcomes.Conclusion:Compared with the free-hand method,the robot-assisted technique provides greater accuracy and reduced radiation exposure.The efficacy of the robot-assisted technique is expected to improve further as experience with its use in surgery grows. 展开更多
关键词 Robotic surgery Pedicle screw placement FREE-HAND FLUOROSCOPY META-ANALYSIS
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Comparative efficacy of proximal femoral nail vs dynamic condylar screw in treating unstable intertrochanteric fractures
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作者 Ahmed Mohamed Yousif Mohamed Monzir Salih +2 位作者 Mohanad Abdulgadir Ayman E Abbas Duha Lutfi Turjuman 《World Journal of Orthopedics》 2024年第8期796-806,共11页
BACKGROUND Among the most frequent hip fractures are trochanteric fractures,which usually occur from low-energy trauma like minor falls,especially in older people with osteoporotic bones.AIM To evaluate the treatment ... BACKGROUND Among the most frequent hip fractures are trochanteric fractures,which usually occur from low-energy trauma like minor falls,especially in older people with osteoporotic bones.AIM To evaluate the treatment efficacy of dynamic condylar screws(DCS)and proximal femoral nails(PFN)for unstable intertrochanteric fractures.METHODS To find pertinent randomized controlled trials and retrospective observational studies comparing PFN with DCS for the management of unstable femoral intertrochanteric fractures,a thorough search was carried out.For research studies published between January 1996 and April 2024,PubMed,EMBASE,Scopus,Web of Science,Cochrane Library,and Google Scholar were all searched.The complete texts of the papers were retrieved,vetted,and independently examined by two investigators.Disputes were settled by consensus,and any disagreements that persisted were arbitrated by a third author.RESULTS This study included six articles,comprising a total of 173 patients.Compared to the DCS,the PFN had a shorter operation time[mean difference(MD):-41.7 min,95%confidence interval(95%CI):-63.04 to-20.35,P=0.0001],higher success rates with closed reduction techniques[risk ratio(RR):34.05,95%CI:11.12-104.31,P<0.00001],and required less intraoperative blood transfusion(MD:-1.4 units,95%CI:-1.80 to-1.00,P<0.00001).Additionally,the PFN showed shorter fracture union time(MD:-6.92 wk,95%CI:-10.27 to-3.57,P<0.0001)and a lower incidence of reoperation(RR:0.37,95%CI:0.17-0.82,P=0.01).However,there was no discernible variation regarding hospital stay,implant-related complications,and infections.CONCLUSION Compared to DCS,PFN offers shorter operative times,reduces the blood transfusions requirements,achieves higher closed reduction success,enables faster fracture healing,and lowers reoperation incidence. 展开更多
关键词 Intertrochanteric fracture UNSTABLE Dynamic condylar screw Proximal femoral nail META-ANALYSIS Comparative study
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Roller Screw and Threaded Chain Speed Reducer: An Experimental Evaluation
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作者 Filiberto Gutiérrez 《Modern Mechanical Engineering》 2024年第1期1-11,共11页
We are developing a speed reducer that can be considered a transformation of a worm gear reducer: the worm is replaced by an inverted roller screw, and the gear is replaced by a threaded chain drive. This configuratio... We are developing a speed reducer that can be considered a transformation of a worm gear reducer: the worm is replaced by an inverted roller screw, and the gear is replaced by a threaded chain drive. This configuration lessens wear, increases load capacity, and improves efficiency. The threaded chain consists of nut-shaped links. This paper presents the results of tests carried out on a prototype with a reduction ratio of 46. 展开更多
关键词 Speed Reducer Inverted Roller screw Chain Drive Threaded Chain Drive
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Clinical Effectiveness of the Plate Screw Internal Fixation Technique in the Treatment of Patients with Traumatic Fractures of Long Bones in the Lower Extremities
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作者 Yong Cai 《Proceedings of Anticancer Research》 2024年第3期115-120,共6页
Objective: To investigate the effectiveness of the plate screw internal fixation technique on the clinical outcomes of patients with traumatic fractures of long bones in the lower extremities. Methods: From January 20... Objective: To investigate the effectiveness of the plate screw internal fixation technique on the clinical outcomes of patients with traumatic fractures of long bones in the lower extremities. Methods: From January 2022 to December 2023, 70 patients with traumatic fractures of long bones in the lower extremities were admitted to the hospital and randomly divided into two groups: the control group and the observation group, each consisting of 35 cases. The control group underwent traditional closed interlocking intramedullary nailing, while the observation group received internal fixation with steel plates and screws. Relevant surgical indicators, treatment effectiveness, and postoperative complication rates were compared between the two groups. Results: The observation group exhibited significantly short surgical duration (80.65 ± 5.01 vs. 88.36 ± 5.26 minutes), fracture healing time (13.27 ± 0.32 vs. 15.52 ± 0.48 weeks), and hospitalization days (10.49 ± 1.13 vs. 16.57 ± 1.15 days) compared to the control group (P = 0.000). The effective treatment rate was significantly higher in the observation group (29/82.86%) than in the control group (21/60.00%), with a significant difference observed (χ2 = 4.480, P = 0.034). Additionally, the complication rate in the observation group (2/5.71%) was significantly lower than that in the control group (8/22.86%), with a correlated difference (χ2 = 4.200, P = 0.040). Conclusion: The plate screw internal fixation technique demonstrates significant clinical efficacy in treating traumatic fractures of long bones in the lower extremities. It improves the healing rate, reduces complications, and represents a safe and effective treatment strategy worthy of widespread use and application. 展开更多
关键词 Plate screw internal fixation technique Traumatic fractures Long bones in the lower extremities EFFECTIVENESS
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Distal clavicle fractures treated by anteroinferior plating with a single screw: Two case reports 被引量:1
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作者 Xin-Lei Zhao Yan-Qing Liu +4 位作者 Jian-Guo Wang You-Cai Liu Jia-Xuan Zhou Bei-Yu Wang Yi-Jun Zhang 《World Journal of Clinical Cases》 SCIE 2023年第30期7502-7507,共6页
BACKGROUND For the treatment of distal clavicle fractures,each treatment method has its own advantages and disadvantages,and there is no optimal surgical solution.CASE SUMMARY Based on this,we report 2 cases of distal... BACKGROUND For the treatment of distal clavicle fractures,each treatment method has its own advantages and disadvantages,and there is no optimal surgical solution.CASE SUMMARY Based on this,we report 2 cases of distal clavicle fractures treated utilizing an anterior inferior plate with a single screw placed in the distal,in anticipation of providing a better surgical approach to distal clavicle fracture treatment.Two patients were admitted to the hospital after trauma with a diagnosis of distal clavicle fracture,and were admitted to the hospital for internal fixation of clavicle fracture by incision and reduction,with good postoperative functional recovery.CONCLUSION With solid postoperative fixation and satisfactory prognostic functional recovery,this technique has been shown to be simple,easy to perform and effective. 展开更多
关键词 Distal clavicle fractures Anteroinferior PLATING Single screw Case report
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Multitrack and multianchor point screw technique combined with the Wiltse approach for lesion debridement for lumbar tuberculosis
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作者 Yu-Fei Yuan Zhi-Xin Ren +5 位作者 Cun Zhang Guan-Jun Li Bing-Zhi Liu Xiao-Dong Li Jie Miao Jian-Fei Li 《World Journal of Clinical Cases》 SCIE 2023年第14期3167-3175,共9页
BACKGROUND The incidence of lumbar tuberculosis is high worldwide,and effective treatment is a continuing problem.AIM To study the safety and efficacy of the multitrack and multianchor point screw technique combined w... BACKGROUND The incidence of lumbar tuberculosis is high worldwide,and effective treatment is a continuing problem.AIM To study the safety and efficacy of the multitrack and multianchor point screw technique combined with the contralateral Wiltse approach for lesion debridement to treat lumbar tuberculosis.METHODS The C-reactive protein(CRP)level,erythrocyte sedimentation rate(ESR),visual analogue scale(VAS)score,oswestry disability index(ODI)and American Spinal Injury Association(ASIA)grade were recorded and analysed pre-and postoperatively.RESULTS The CRP level and ESR returned to normal,and the VAS score and ODI were decreased at 3 mo postoperatively,with significant differences compared with the preoperative values(P<0.01).Neurological dysfunction was relieved,and the ASIA grade increased,with no adverse events.CONCLUSION The multitrack,multianchor point screw fixation technique combined with the contralateral Wiltse approach for debridement is an effective and safe method for the treatment of lumbar tuberculosis. 展开更多
关键词 Lumbar spine TUBERCULOSIS DEBRIDEMENT Pedicle screw Cortical bone trajectory screw Wiltse approach
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Gravity-Based Kinetostatic Modeling of Parallel Manipulators Using Screw Theory
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作者 Chao Yang Fengli Huang +1 位作者 Wei Ye Qiaohong Chen 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2023年第6期73-86,共14页
The pose accuracy of parallel manipulators(PMs)is a key index to measure their performance.Establishing the grav-ity-based kinetostatic model of a parallel robot provides an important basis for its error composition a... The pose accuracy of parallel manipulators(PMs)is a key index to measure their performance.Establishing the grav-ity-based kinetostatic model of a parallel robot provides an important basis for its error composition and accuracy improvement.In this paper,a kinetostatic modeling approach that takes real gravity distribution into consideration is proposed to analyze the influence of gravity on the infinitesimal twist and actuator forces of PMs.First,the duality of the twist screw and constraint wrenches are used to derive the gravity-attached constraint wrenches independent of the external load and the limb stiffness matrix corresponding to the kinematics-based constraint wrenches.Sec-ond,the gravity model of the mechanism is established based on the screw theory and the principle of virtual work.Finally,the analytical formulas of the infinitesimal twist and the actuator force of PMs are obtained,and the influences of the external load,platform gravity,and rod gravity on the stiffness of the mechanism are decoupled.The non-overconstrained 3RPS and overconstrained 2PRU-UPR PMs are taken as examples to verify the proposed method.This research proposes a methodology to analyze the infinitesimal deformation of the mechanism under the influence of gravity. 展开更多
关键词 Parallel manipulator Kinetostatic model GRAVITY screw theory
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Management of Isolated Coronal Fractures of Distal Humeral Epiphysis by Herbert Screw
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作者 Yassine Ben Bouzid Rida-Allah Bassir +4 位作者 Monsef Boufettal Jalal Mekkaoui Mohamed Kharmaz Moulay Omar Lamrani Mohamed Saleh Berrada 《Open Journal of Orthopedics》 2023年第2期50-54,共5页
Isolated fractures of the distal humerus are rare. Their diagnosis is often late, and treatment has progressed but serious complications may occur. We conducted a retrospective study of a series of 10 cases at the Dep... Isolated fractures of the distal humerus are rare. Their diagnosis is often late, and treatment has progressed but serious complications may occur. We conducted a retrospective study of a series of 10 cases at the Department of Orthopedic and Traumatologic Surgery of the Ibn Sina University Hospital in Rabat over a 4-year period, from January 2018 to January 2022. All our cases were treated surgically with Herbert screws. The functional, clinical and radiological outcome was satisfactory with a return to pre-fracture activity in all patients. 展开更多
关键词 ELBOW CAPITELLUM Herbert screw
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Experimental Investigation on the Strength and Ductility Performance of Steel-Timber-Steel Joints with Screw and Steel-Tube Fasteners
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作者 Huifeng Yang Mingwang Wu +3 位作者 Rixin Gu Hang Cao Kai Xiao Benkai Shi 《Journal of Renewable Materials》 EI 2023年第12期4175-4195,共21页
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 wer... 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. 展开更多
关键词 Steel-timber-steel joint screw steel-tube DUCTILITY experimental investigation timber structure
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Nail Holding Performance of Self-Tapping Screws on Masson Pine and Chinese Fir Dimension Lumbers
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作者 De Li Bengang Zhang +7 位作者 Yuan Tu Guoming Xiao Meifen Tian Xiaoxue Xu Xiao Zhong Qiaoyan Zhang Zhigang Wu Jiankun Liang 《Journal of Renewable Materials》 EI 2023年第10期3725-3738,共14页
Screw connection is a type most commonly applied to timber structures.As important commercial tree species in China,Masson pine and Chinese fir have the potential to prepare wood structures.In this study,the effects o... Screw connection is a type most commonly applied to timber structures.As important commercial tree species in China,Masson pine and Chinese fir have the potential to prepare wood structures.In this study,the effects of the diameter of the self-tapping screw and the guiding bores on the nail holding performance on different sections of Masson pine and Chinese fir dimension lumbers were mainly explored.The results showed that:(1)The nail holding strength of the tangential section was the maximum,followed by that of the radial section,and that of the cross section was the minimum.(2)The nail holding strength of Masson pine was higher than that of Chinese fir.(3)The nail holding strength grew with the increase in the diameter of self-tapping screws,but a large diameter would lead to plastic cracking of the timber,thus further affecting the nail holding strength.Masson pine and Chinese fir reached the maximum nail holding strength when the diameter of self-tapping screws was 3.5 mm.(4)Under a large diameter of screws,prefabricated guiding bores could mitigate timber cracking and improve its nail holding strength.(5)Prefabricated guiding bores were more necessary for the screw connection of Masson pine.The results obtained could provide a scientific basis for the screw connection design of Masson pine and Chinese fir timber structures. 展开更多
关键词 Masson pine Chinese fir self-tapping screws nail holding performance
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Crossed Intralaminar Screws for Fusion of the Cervicothoracic Junction and the Thoracic Spine: The Experience in an Iberic Service with Case Series and Review of the Current Literature with Technique Description
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作者 Marcel Sincari Margarida Conceição 《Surgical Science》 2023年第3期203-220,共18页
The treatment of pathologies in the thoracic spine is a challenge. The periodic failure of pedicle screw insertion and anatomical variations make the search for an alternative to pedicle screws in thoracic spine surge... The treatment of pathologies in the thoracic spine is a challenge. The periodic failure of pedicle screw insertion and anatomical variations make the search for an alternative to pedicle screws in thoracic spine surgery necessary. The interlaminar crossed screws is a well-known and secure method for fusion in cervical spine, and in thoracic spine there used to be insufficient clinical data to support this technique, until now. We demonstrate in an initial series of 10 cases treated with interlaminar fusion in association of other fusion techniques in the thoracic spine with good results. Objective: Intralaminar screws have been shown to be a biomechanical salvage technique in the thoracic spine, especially in long cervicothoracic, thoracic and thoracolumbar fixation. The goals of this article are to demonstrate our initial experience and the range of indications for thoracic crossed intralaminar screws. Methods: In this article we describe our initial series performed at S&#227o Teot&#243nio Hospital in Viseu, Portugal, and our results, and also provide a comprehensive review of the recent literature in the use of intralaminar crossed fixation. 展开更多
关键词 Crossed Intralaminar Spinolaminar Angle THORACIC Imaging Lamina screws Spinal Fusion/Instrumentation/Methods Thoracic Vertebrae
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Accuracy of screw placement in the apical region of Lenke 1 adolescent idiopathic scoliosis surgery using a calibration technique for the intraoperative navigation error
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作者 CHEN Huan-xiong HE Xian-bo +6 位作者 LI Guo-jun TANG Song-jie ZHONG Zhen-hao HUANG Tao LIN You-cai LIN Su-yu MENG Zhi-bin 《Journal of Hainan Medical University》 CAS 2023年第6期43-50,共8页
Objective:To study the position and the grade of screw perforation in the apical region of adolescent idiopathic scoliosis(AIS)surgery using a calibration technique for the intraoperative navigation error,and to analy... Objective:To study the position and the grade of screw perforation in the apical region of adolescent idiopathic scoliosis(AIS)surgery using a calibration technique for the intraoperative navigation error,and to analyze the related factors of navigation deviation and the clinical significance of the calibration technique.Methods:From 2017 to 2020,a total of 60 Lenke 1 AIS surgical cases were enrolled in this research.The 30 cases received surgery using the intraoperative navigation system(Navigation group)and another 30 cases were assisted with intraoperative navigation system with calibration technique(Calibration group)for the intraoperative navigation error.The basic information and radiological data of the both groups were all recorded.According to the Fu Chang-feng’s pedicle channel classification system,the pedicle on the apical region of the two groups was classified.And then the accuracy of screw placement of the two groups was evaluated according to the Rao’s classification.Results:A total of 600 screws were placed in the two groups.The 297 and 303 pedicle screws were implanted in the navigation group and the calibration group,respectively.In the apical region of the calibration group,the rates of the grade 0 screw placement in type A,B and C pedicle were 95.7%,86.7%and 68.9%respectively.It was a statistically significant difference from the 73.9%,66.9%and 30.0%in the navigation group respectively(P<0.05).In the calibration group,the rates of the medial cortical perforation in the type A,B,C and D pedicle were 0%,1.6%,1.6%and 0%,respectively.The corresponding rates were 16.3%,16.9%,30.0%and 47.6%in the navigation group,respectively.Moreover,in the concave side of the apical region of the calibration group,the rates of the medial cortical perforation in the type A,B,C and D pedicle were 0%,3.6%,2.6%and 0%,respectively.Compared with the calibration group,the corresponding rates were higher in the navigation group(34.4%,25.9%,37.2%and 60.0%,respectively).No serious complications such as spinal cord or neurovascular injury occurred for the two groups.Conclusion:Compared with the intraoperative navigation system,the calibration technique for the intraoperative navigation error could provide the higher accuracy of pedicle screw placement in the apical region of the major curve,the lower medial cortical perforation rate,the less screws misplacement rate on the concave side and the less complication rate of the severe Lenke 1 AIS patients. 展开更多
关键词 Adolescent idiopathic scoliosis Apical region Pedicle channel classification Pedicle screw Navigation error
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Research and experimental analysis of precision degradation method based on the ball screw mechanism
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作者 孔德顺 GAO Xiangsheng JIANG Huizeng 《High Technology Letters》 EI CAS 2023年第3期247-256,共10页
As a key transmission component in computer numerical control(CNC) machine tools,the ball screw mechanism(BSM) is usually investigated under working load conditions. Its accuracy degradation process is relatively long... As a key transmission component in computer numerical control(CNC) machine tools,the ball screw mechanism(BSM) is usually investigated under working load conditions. Its accuracy degradation process is relatively long,which is not conducive to the design and development of new products. In this paper,the normal wear depth of the BSM nut raceway is calculated under the variable speed operation condition using the fractal wear analysis method and the BSM’s accelerated degradation proportional wear model. Parameters of the acceleration degradation model of the double-nut preloaded ball screw pair are calculated based on the physical simulation results. The accelerated degradation test platform of the BSM is designed and manufactured to calculate the raceway wear model when the lubrication condition is broken under the variable-speed inertial load and the boundary lubrication condition under the uniform speed state. Three load forces and two samples are selected for the accelerated degradation test of the BSM. The measured friction torque of the BSM is employed as the evaluation index of the accuracy degradation test. In addition,the life cycle of the accuracy retention is accurately calculated by employing the parameters of the physical simulation model of the BSM. The calculations mentioned above can be used to estimate BSM’s accuracy performance degradation law under normal operating conditions. The application of the proposed model provides a new research method for researching the precision retention of the BSM. 展开更多
关键词 ball screw mechanism(BSM) fractal theory wear model accelerated degradation method friction torque precision retention
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不同推进比下螺旋桩在砂土中安装力的离散元研究 被引量:1
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作者 王乐 李钰 +3 位作者 徐志军 刘波 张春会 田英辉 《岩土工程学报》 EI CAS CSCD 北大核心 2024年第6期1166-1176,共11页
螺旋桩作为一种颇具潜力的海上风电基础形式,其安装问题是螺旋桩能否成功应用在海上风电工程中的关键。基于离散元方法,采用PFC^(3D)模拟分析了螺旋桩在不同推进比下安装时的桩身受力情况以及对周围土体的影响。宏观上,研究了螺旋桩在... 螺旋桩作为一种颇具潜力的海上风电基础形式,其安装问题是螺旋桩能否成功应用在海上风电工程中的关键。基于离散元方法,采用PFC^(3D)模拟分析了螺旋桩在不同推进比下安装时的桩身受力情况以及对周围土体的影响。宏观上,研究了螺旋桩在不同推进比下安装时螺旋桩连杆侧壁、连杆端部、螺旋叶片上下表面的受力变化规律;微观上,分析了螺旋桩安装过程中桩周土体孔隙率、配位数及应力变化规律。研究表明:随着推进比的减小,螺旋桩安装时受到的竖向力与扭矩也随之降低,对桩周土体的扰动也更小;螺旋桩在推进比为1时安装与在推进比小于1时安装存在两种不同的安装机制。研究结果对进一步确定螺旋桩在不同推进比下的安装条件具有一定意义。 展开更多
关键词 螺旋桩 推进比 砂土 离散元法
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Fixation of Calcaneal Tuberosity Beavis II Fracture in Elderly Patients Using Locking Plate Combined with Tension Screw
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作者 De-Jian Li Jia-Wen He +2 位作者 Jian-Hua Zhou Cheng-Qing Yi Qi-Kai Huang 《Biomedical Engineering Communications》 2023年第1期24-28,共5页
Background:Calcaneus is the largest bone of foot and the main load-bearing structure of heel.The incidence of simple calcaneal tubercle avulsion fracture is low,accounting for about 1%to 3%of all calcaneal fractures.B... Background:Calcaneus is the largest bone of foot and the main load-bearing structure of heel.The incidence of simple calcaneal tubercle avulsion fracture is low,accounting for about 1%to 3%of all calcaneal fractures.Beavis II fracture has large bone fracture,obvious displacement,obvious soft tissue irritation,and often leads to skin necrosis.It needs surgical treatment,reduction and fixation as soon as possible.Although open reduction and tension screw internal fixation is used for Beavis II calcaneal tubercle fracture,but the failure rate is more common.Methods:This study retrospectively analyzed the surgical treatment of calcaneal tubercle Beavis II fracture over 55 years old in our hospital from January 2013 to January 2019.The patients were treated with tension screw combined with locking plate,and followed up and analyzed.Results:12 patients in this group were followed up for 12 to 36 months(mean 20 months).After operation,the fracture healed smoothly in all patients,the healing time was 8 to 12 weeks(mean 10.7 weeks),and there were no complications such as poor incision healing,fracture displacement,internal fixation loosening,fracture and so on.When the patients were followed up 18 weeks after operation,the AOFAS score was 47 to 100,with an average of 91.1,of which 8 cases were excellent,3 good and 1 poor,with an excellent and good rate of 91.7%.Conclusion:Our hospital has been treated with tension screw combined with locking plate,fixed firmly,can early functional exercise,achieved good results. 展开更多
关键词 calcaneal tubercle Beavis II fracture locking plate tension screw elderly patients
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股骨颈骨折空心钉内固定后股骨近端骨质疏松的有限元分析 被引量:3
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作者 薛晓峰 魏永康 +7 位作者 乔晓红 杜玉勇 牛建军 任立新 杨慧峰 张治民 郭媛 陈维毅 《中国组织工程研究》 CAS 北大核心 2024年第6期862-867,共6页
背景:股骨颈骨折空心钉内固定术后由于患肢短期内常常不能负重,且高刚度的内植物对骨折断端存在应力遮挡效应,易导致患肢出现骨质疏松,股骨近端生物力学分布发生变化,术后股骨头坏死发病率较高,目前关于股骨颈骨折术后股骨近端骨质疏松... 背景:股骨颈骨折空心钉内固定术后由于患肢短期内常常不能负重,且高刚度的内植物对骨折断端存在应力遮挡效应,易导致患肢出现骨质疏松,股骨近端生物力学分布发生变化,术后股骨头坏死发病率较高,目前关于股骨颈骨折术后股骨近端骨质疏松对股骨近端及空心钉生物力学影响的研究较少。目的:通过有限元分析探讨股骨颈骨折术后发生骨质疏松对空心钉内固定治疗的生物力学影响,探究生物力学因素在股骨头坏死进程中的作用。方法:获取1例股骨颈骨折患者股骨CT扫描数据,利用Mimics 19.0、3-Matic、UG 11.0、Hypermesh 14.0、Abaqus软件建立空心钉治疗股骨颈骨折的股骨近端模型,利用Abaqus软件分析1种术后股骨近端无骨质疏松、3种术后股骨近端骨质疏松的有限元模型,测量分析4种模型不同部件的应力、接触压力、位移峰值及云图,对比分析股骨头内部应力变化及分布情况。结果与结论:股骨头及下前空心钉的应力、接触压力随骨质疏松程度变化较大,4种模型的位移峰值随着骨质疏松程度加重而缓慢增长。通过单因素方差分析,结果显示骨质疏松程度对不同部件的应力、接触压力、位移峰值无显著性影响,股骨头内部应力分布随骨质疏松发生相应变化,股骨近端的生物力学环境变化对股骨头坏死有着重要影响。 展开更多
关键词 股骨 股骨颈骨折 空心钉 内固定术 骨质疏松 股骨头坏死 生物力学 有限元
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骨科机器人联合Starr骨盆复位架治疗Tile C型骨盆环骨折 被引量:1
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作者 姜刚强 焦福德 +3 位作者 应霁翀 虞天明 刘建磊 庄云强 《中国骨伤》 CAS CSCD 2024年第5期445-450,共6页
目的:探讨骨科机器人联合Starr骨盆复位架治疗Tile C型骨盆环骨折的临床疗效。方法:2019年10月至2021年5月采用机器人联合Starr骨盆复位架治疗14例Tile C型骨盆环骨折患者,男9例,女5例;年龄33~69岁。14例患者均为新鲜闭合骨折且不合并... 目的:探讨骨科机器人联合Starr骨盆复位架治疗Tile C型骨盆环骨折的临床疗效。方法:2019年10月至2021年5月采用机器人联合Starr骨盆复位架治疗14例Tile C型骨盆环骨折患者,男9例,女5例;年龄33~69岁。14例患者均为新鲜闭合骨折且不合并股骨、胫腓骨骨折等损伤。入院后4~7 d完成手术,术中在可透视碳素床,通过Starr骨盆复位架牵引复位骨盆环,联合骨科机器人治疗C型骨盆环骨折。观察手术时间、出血量、单枚螺钉置入透视次数、骨折复位质量、患肢功能及并发症等。采用Matta评分标准进行放射学复位评价,末次随访采用Majeed骨盆功能评分系统进行临床疗效评价。结果:14例患者均顺利完成手术,手术时间84~141 min,手术出血量20~50 ml,单枚螺钉置入透视次数4~9次。14例患者均获得随访,随访时间12~24个月。术后所有骨折获得骨性愈合,愈合时间3~7个月,未发现内固定断裂、螺钉松动、感染、神经损伤等并发症。依据Matta影像学复位评估标准:优9例,良4例,可1例。末次随访采用Majeed骨盆功能评分系统:优10例,良4例。结论:机器人联合Starr骨盆复位架治疗C型骨盆环新鲜骨折操作简单、缩短了手术和麻醉时间、并发症少,降低了手术风险,实现了骨盆骨折的微创治疗。但对于陈旧性骨折,因骨折复位困难,该技术并不适用。对于螺钉进钉点区域粉碎的骨折,通道螺钉置入困难,建议采用其他方式固定。对于伴有骨盆外伤史或骨盆发育异常者,术前需仔细评估有无经皮螺钉通道,避免损伤神经、血管。 展开更多
关键词 骨科机器人 Starr骨盆复位架 骨盆骨折 螺钉 内固定
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