Additive manufactured osseointegrated screws with hierarchical design

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.

Roller Screw and Threaded Chain Speed Reducer: An Experimental Evaluation

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.

Distal clavicle fractures treated by anteroinferior plating with a single screw: Two case reports

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.

Multitrack and multianchor point screw technique combined with the Wiltse approach for lesion debridement for lumbar tuberculosis

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.

Gravity-Based Kinetostatic Modeling of Parallel Manipulators Using Screw Theory

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.

Experimental Investigation on the Strength and Ductility Performance of Steel-Timber-Steel Joints with Screw and Steel-Tube Fasteners

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.

Management of Isolated Coronal Fractures of Distal Humeral Epiphysis by Herbert Screw

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.

Nail Holding Performance of Self-Tapping Screws on Masson Pine and Chinese Fir Dimension Lumbers

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.

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

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.

Accuracy of screw placement in the apical region of Lenke 1 adolescent idiopathic scoliosis surgery using a calibration technique for the intraoperative navigation error

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.

Research and experimental analysis of precision degradation method based on the ball screw mechanism

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.

Fixation of Calcaneal Tuberosity Beavis II Fracture in Elderly Patients Using Locking Plate Combined with Tension Screw

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.

两种内固定治疗股骨颈骨折的疗效比较

目的比较空心加压螺钉(CCS)和股骨颈动力交叉钉系统(FNS)固定治疗股骨颈骨折的疗效。方法将42例股骨颈骨折患者按照内固定方式不同分为FNS组(采用FNS固定治疗,15例)和CCS组(采用CCS固定治疗,27例)。比较两组切口长度、术中出血量、术中透视次数、手术时间、术后住院时间、并发症发生情况、下地时间、骨折愈合时间、步态情况。结果患者均获得随访,时间12~14个月。切口长度CCS组短于FNS组(P<0.05);术中透视次数、手术时间FNS组少(短)于CCS组(P<0.05);术中出血量、术后住院时间两组比较差异均无统计学意义(P>0.05)。两组均无切口感染、骨折不愈合等并发症发生;术后约3个月CCS组2例出现CCS松动及退钉现象,经减少活动后未影响骨折愈合。下地部分负重时间、骨折愈合时间FNS组均短于CCS组(P<0.05)。末次随访时两组患者均可部分负重行走。结论与CCS固定相比,FNS固定治疗股骨颈骨折术中透视次数少、手术时间短,且固定稳定、牢靠,在“早活动、晚负重”原则下利于患肢功能锻炼,更有助于促进骨折愈合。

Development of Technology and Equipment for Non-destructive Testing of Defects in Sewing Mandrels of a Three-roll Screw Mill 30-80

The conditions of heating and cooling of piercing mandrels made of 4X5MFS steel of a three-roll screw mill 30-80 in the production of a closed cavity of steel vessels of small volume are determined.It is established that multiple cycles of heating up to 600℃ and cooling with water up to 80℃ for about 7 seconds/1 cycle lead to the formation of ridges,shells and cracks on the surface and in the volume of the tool.The loss of structural strength of the material leads to the breakdown of the mandrel during the stitching process.The technique and equipment of magnetic powder control have been developed to establish the dynamics of the growth of internal and external defects of mandrels.An equation is obtained that allows determining the increase in the number of defects in the sewing tool of a screw rolling mill.The technology of non-destructive testing made it possible to develop a rational plan for replacing the sewing mandrels,which allows for predicting the appearance of defects leading to a complex breakdown of the deforming tool at the NPO Pribor machine-building enterprise.

后牙区种植修复基台及其螺丝折断原因的回顾性研究

目的分析影响后牙区种植修复基台及其螺丝折断发生的因素并探讨预防措施。方法回顾2010年1月至2015年12月在郑州大学第一附属医院口腔种植科完成后牙区种植修复且已行使功能>5 a的患者病历资料,统计分析患者种植修复基台及其螺丝折断的发生情况及其影响因素,并探讨相应的预防措施。结果本研究共纳入1055名患者(男500名,女555名),共植入1954颗种植体,其中12名患者(男8名,女4名)的12颗种植体发生种植修复基台及其螺丝折断,发生时年龄为(48.17±8.04)岁,种植修复体平均行使功能时间(6.50±1.45)a。12名患者中11例出现种植修复基台折断,1例种植修复基台与螺丝同时折断,种植修复基台及其螺丝折断的发生率为0.61%。结论种植修复基台及其螺丝折断的原因包括咬合力过大、不良咬合习惯(夜磨牙、紧咬牙和偏侧咀嚼)、种植牙对颌是天然牙、内连接种植体角度基台使用出现基台应力集中。

基于无线随钻测量式超短半径水平井钻井技术

为了解决油田开发后期老井产量低、含水高的难题,通过采用小尺寸高弯曲度MWD随钻仪器配合高造斜率螺杆的方法,实现了在老井上部井段侧钻出超短半径水平井,攻关研究大曲率造斜和水平钻进的技术,通过设计研发小尺寸高弯曲度MWD随钻仪器、高造斜率螺杆等专用工具,并结合现场施工要求,创新基于无线随钻测量方式的超短半径水平井钻井技术。结果表明:该技术具有施工效率高、实时监测井下参数、轨迹控制精度高等优点,可以实现老井剩余油储层定向挖潜改造,扩大泄油面积,改善油井生产条件,提高采收率。

Clinical Outcomes and Prehabilitation Strategies of Patients Treated with Cement-Screw Technique for Tibial Defects in Total Knee Arthroplasty

Objective: To investigate the clinical efficacy of the cement-screw technique in repairing tibial plateau bone defects in total knee arthroplasty (TKA) recipients and summarize the preoperative prehabilitation strategies for such surgeries. Methods: A total of 33 TKA recipients (45 knees) in our department underwent repair of unilateral or bilateral tibial defects using the cement-screw technique. The subjects were divided into two groups based on the differences in preoperative interventions. The control group received routine preoperative health education according to the consensus, while the observation group received instructive and standardized prehabilitation exercises for four weeks in addition to the routine education. Scale scores, intraoperative parameters, and postoperative recovery indicators were recorded at different time pointsand subjected to statistical analysis for intra-group and inter-group differences. All subjects underwent long-term follow-up for at least 24 months. Results: Within each group at different time points, there were statistically significant differences in VAS, ROM, and HSS scores (p Conclusions: Cement-screw technique for repairing tibial plateau bone defects in TKA recipients can significantly relieve pain, and improve joint function. Prehabilitation can improve preoperative rehabilitation reserves in these patients, accelerate postoperative recovery, and contribute to better short-term clinical outcomes.

V区温度及螺杆转速对挤压膨化牛肉制品理化性质的影响

利用挤压膨化技术加工高粱-山药-牛肉混合物料,以水溶性、吸水性、色差值、粒度、质构、膨化度、糊化度及红外光谱各基团峰值为指标,分析V区温度和螺杆转速对挤压膨化产品理化性质的影响。结果表明,提高V区温度能够提高产品的红度值、黄度值、硬度、脆度和咀嚼度,吸水性、水溶性、粒度、膨化度、糊化度及红外光谱各基团峰值呈先上升后下降的趋势,亮度值显著下降(P<0.05);同时,随着螺杆转速的提升,产品的红度值、黄度值和糊化度显著下降(P<0.05),吸水性、水溶性、粒度和膨化度呈先上升后下降的趋势,硬度、脆度、咀嚼度及红外光谱各基团峰值先下降后上升,亮度值显著下降(P<0.05)。综合理化指标确定V区温度最佳值为150℃,螺杆转速最佳值为160 r/min。

3D打印导向器与导航下引导骶髂螺钉置入的对比研究

目的 比较3D打印螺钉导向器与导航下引导骶髂螺钉置入在骶髂关节损伤治疗中的临床疗效。方法 分析2018年6月至2021年6月收治的骶髂关节损伤32例患者资料,按照螺钉引导方式不同分为3D打印螺钉导向器组(17例)和导航组(15例),其中导向器组男13例,女4例;年龄23~56岁,平均(37.81±9.73)岁;Tile分型,B型10例,C型7例。导航组男12例,女3例;年龄23~58岁,平均(36.23±9.35)岁;Tile分型,B型9例,C型6例。比较两组术中透视次数、置钉时间、术中出血量、术后并发症等,采用Majeed评分在术后1年对骨盆功能进行评价,采用Matta评分对骨折复位质量进行评价。结果 两组患者术后均无伤口感染和神经损伤并发症出现。患者均获随访,随访时间12~32个月,平均(19.82±0.25)个月。两组患者透视次数方面比较差异无统计学意义(P>0.05)。导向器组出血量稍多,与导航组比较差异有统计学意义(P<0.05)。导向器组置钉时间要少于导航组,两组比较差异有统计学意义(P<0.05)。按照Matta评分标准:导向器组优12例,良4例,可1例;导航组优11例,良3例,可1例(P>0.05)。术后1年随防时,按照Majeed评分标准:导向器组评分67~93分,平均(85.76±6.86)分;导航组评分68~92分,平均(86.47±7.37)分(P>0.05)。结论 采用3D打印螺钉导向器引导置入骶髂螺钉治疗骶髂关节损伤,具有术中置钉时间少、置钉准确等优点,且不需要导航等高科技设备,在基层临床工作中可以推广应用。

隔震装置阻尼机构的参数设计与振动台试验

为了改善浮放物体隔震装置中阻尼力的施加方式,研制出一款阻尼机构。对其构造和工作机理进行阐述,推导出了它的力学特征表达式,并验证了分析模型的准确性。结合某文物隔震装置的目标性能,利用数值方法对阻尼机构的参数进行设计,并对比振动台试验。结果表明:该阻尼机构结构简单,性能稳定;经阻尼参数优化后的隔震装置在满足位移限值的情况下达到了设定的隔震目标;试验与数值分析结果相吻合,证明了阻尼机构参数设计的正确性,同时也检验了隔震装置的安装和运行质量。其中,试验与数值分析结果的吻合程度,尤其是位移时程曲线的吻合程度,可为浮放物体隔震装置的方案对比和质量评估提供思路。