Bone Density and Mechanical Properties in Femoral Bone of Swim Loaded Aged Mice

Effects of swirnming on bone density and mechanical properties of femur were investigated in aged male and female mice. R/1 strain of senescence accelerated mouse (SAM) at eleven months old was used. Two groups of males and two groups of females each consisting of 7 mice were used. One male and one female groups were loaded with a swim regiment of 40 min a day, 5 days a week for 6 consecutive weeks. The remaining groups were used as the controls. All mice were fed with the standard diet and water ad libitum during the experiments.The results of this study indicated that (i) the hady weight was significantly (P<0.05) lower in the swimming groups than in the control groups in boh sexes. (ii) The bone density was significantly higher (P <0.05) in the swimming groups than in the control groups in boh sexes. However, there was no sighficant difference in cortical thickness index. (iii) In the mechanical properties of bone, there were no significant differences in the level of the maximum breaking force, the ultimate stress and the deformation between the swimndng and the contro groups in beth sexes. However, the elasticity of the bone of the female hoce in the swimming group was significantly higher (P<0.05) than that of the control group.These results suggest that regimented swimming for the aged mice might suppress age-associated bone loss, and the effect of exercise in the females is greater that in the males.

A multiscale 3D finite element analysis of fluid/solute transport in mechanically loaded bone

The transport of fluid, nutrients, and signaling molecules in the bone lacunar-canalicular system （LCS） is critical for osteocyte survival and function. We have applied the fluorescence recovery after photobleaching （FRAP） approach to quantify load-induced fluid and solute transport in the LCS in situ, but the measurements were limited to cortical regions 30-50 μm underneath the periosteum due to the constrains of laser penetration. With this work, we aimed to expand our understanding of load-induced fluid and solute transport in both trabecular and cortical bone using a multiscaled image-based finite element analysis （FEA） approach. An intact murine tibia was first re-constructed from microCT images into a three-dimensional （3D） linear elastic FEA model, and the matrix deformations at various locations were calculated under axial loading. A segment of the above 3D model was then imported to the biphasic poroelasticity analysis platform （FEBio） to predict load-induced fluid pressure fields, and interstitial solute/fluid flows through LCS in both cortical and trabecular regions. Further, secondary flow effects such as the shear stress and/or drag force acting on osteocytes, the presumed mechano-sensors in bone, were derived using the previously developed ultrastructural model of Brinkman flow in the canaliculi. The material properties assumed in the FEA models were validated against previously obtained strain and FRAP transport data measured on the cortical cortex. Our results demonstrated the feasibility of this computational approach in estimating the fluid flux in the LCS and the cellular stimulation forces （shear and drag forces） for osteocytes in any cortical and trabecular bone locations, allowing further studies of how the activation of osteocytes correlates with in vivo functional bone formation. The study provides a promising platform to reveal potential cellular mechanisms underlying the anabolic power of exercises and physical activities in treating patients with skeletal deficiencies.

The Behavior of New Hydrophilic Composite Bone Cements for Immediate Loading of Dental Implant

We introduced the hydrophilic groups to acrylic bone cement to improve compliance and achieve more interdigitation between the bone and the acrylic bone cement in order to create better substrates for immediate loading. FTIR-ATR, contact angle, and maximum breach torque were employed for measurement. The results reveal that the introduction of hydrophilic functional groups has increased PMMA＇s surface hydrophilicity after contact angle test. FTIR-ATR results suggest the hydrophilic groups participate in the polymerization reactions, and maximum breach torque of the hydrophilic acrylic bone cements is near 110 Ncm torque. Those effects make it possible for conventional acrylic bone cement application in immediate loading of dental implant.

Development of an Artificial Finger-Like Knee Loading Device to Promote Bone Health

This study presents the development of an innovative artificial finger-like device that provides position specific mechanical loads at the end of the long bone and induces mechanotransduction in bone. Bone cells such as osteoblasts are the mechanosensitive cells that regulate bone remodelling. When they receive gentle, periodic mechanical loads, new bone formation is promoted. The proposed device is an under-actuated multi-fingered artificial hand with 4 fingers, each having two phalanges. These fingers are connected by mechanical linkages and operated by a worm gearing mechanism. With the help of 3D printing technology, a prototype device was built mostly using plastic materials. The experimental validation results show that the device is capable of generating necessary forces at the desired frequencies, which are suitable for the stimulation of bone cells and the promotion of bone formation. It is recommended that the device be tested in a clinical study for confirming its safety and efficacy with patients.

Simultaneous Upper and Lower Jaw Extractions, Autogenous Bone Augmentation and Temporary Implant Placement with Immediate Loading

Aims: We expanded the known technique for simultaneously augmenting an atrophic maxilla and placement of immediate provisional implants (IPI), followed by immediate loading by performing surgery in both jaws simultaneously. Feasibility of this new technique, implant survival and success were evaluated as well as prosthetic success. Materials and Methods: All patients undergoing simultaneous bone grafting and IPI placement with immediate loading at our institute between the 1st of June 2016 and the 30th of May 2018 were included and followed up for at least one year postoperatively. Results: 3 patients were followed for a mean period of 25.67 months (20 - 29 months). 33 IPIs were placed. All were immobile at second stage surgery without signs of infection. No provisional bridges were lost and no infections were noted. After second stage surgery, none of these 36 final dental implants were lost. There was some bone loss at one implant. In all patients, good functional and aesthetic results were obtained without any unforeseen complications. This renders the implant survival at 100% and the success rate at 97%. Conclusion: The technique is complex due to the intricate step-by-step process that is required and depends on a dedicated team to ensure a proper workflow. When performed correctly, the protocol shows good and predictable results.

Dynamic Fluid Flow Mechanical Stimulation Modulates Bone Marrow Mesenchymal Stem Cells

Osteoblasts are derived from mesenchymal stem cells （MSCs）, which initiate and regulate bone formation. New strategies for osteoporosis treatments have aimed to control the fate of MSCs. While functional disuse decreases MSC growth and osteogenic potentials, mechanical signals enhance MSC quantity and bias their differentiation toward osteoblastogenesis. Through a non-invasive dynamic hydraulic stimulation （DHS）, we have found that DHS can mitigate trabecular bone loss in a functional disuse model via rat hindlimb suspension （HLS）. To further elucidate the downstream cellular effect of DHS and its potential mechanism underlying the bone quality enhancement, a longitudinal in vivo study was designed to evaluate the MSC populations in response to DHS over 3, 7, 14, and 21 days. Five-month old female Sprague Dawley rats were divided into three groups for each time point： age-matched control, HLS, and HLS＋DHS. DHS was delivered to the right mid-tibiae with a daily ＂10 min on-5 min off-10 min on＂ loading regime for five days/week. At each sacrifice time point, bone marrow MSCs of the stimulated and control tibiae were isolated through specific cell surface markers and quantified by flow cytometry analysis. A strong time-dependent manner of bone marrow MSC induction was observed in response to DHS, which peaked on day 14. After 21 days, this effect of DHS was diminished. This study indicates that the MSC pool is positively influenced by the mechanical signals driven by DHS. Coinciding with our previous findings of mitigation of disuse bone loss, DHS induced changes in MSC number may bias the differentiation of the MSC population towards osteoblastogenesis, thereby promoting bone formation under disuse conditions. This study provides insights into the mechanism of time-sensitive MSC induction in response to mechanical loading, and for the optimal design of osteovorosis treatments.

Theoretical Solutions of Dynamic Responses of Cancellous Bone

Human bone may be damaged by impact in the cases of traffic accidents and ship impact. The impact responses of cancellous bone were analyzed based on the two-phase media theory. A direct analytical method is introduced for solving this type of problems. First, flow function and potential function were introduced to decouple the controlling equations. Then direction solving method was used to obtain the solution. The solution is determined by the parameters of a (related with wave speed) and b (related with damping), as well as the boundary conditions. These two parameters a and b determine the propagation speed of the responses along the bone and the attenuation rate. It is shown that the responses: deformation, stress and pressure of the corpus medullae caused by loading, propagate toward the other end when the impact is acted on one end of the bone. The responses are discontinuous during propagate. The discontinuous surface moves with a constant speed. The responses at the cross section increase gradually from the bottom to the top because of the distribution of the loading at the boundary. The solutions can be used as the basis for certification of numerical simulation as well as the design of impact prevention of bone.

载抗生素骨水泥治疗糖尿病足坏死性筋膜炎致小腿筋膜室综合征

背景:目前坏死性筋膜炎的治疗方法大多是充分彻底清创后使用负压封闭吸引,该方法需要反复多次清创才能彻底清除坏死感染组织,给患者造成严重的身体负担和经济负担。目的:介绍一种临床少见的病例——糖尿病足坏死性筋膜炎导致的小腿筋膜室综合征,总结使用载抗生素骨水泥进行治疗与综合管理的临床经验。方法:选择2017年8月至2020年8月苏州大学附属无锡九院收治的糖尿病性坏死性筋膜炎导致的小腿筋膜室综合征患者6例,男5例,女1例,平均年龄54岁,围术期整体把控患者全身情况并进行全身营养支撑治疗,所有患者均一期行彻底清创+载抗生素骨水泥填塞+负压封闭引流以控制感染、二期取出骨水泥并行创面修复治疗。出院后随访时观察患者创面愈合情况及有无红肿渗液发生。结果与结论:①4例患者经过2次载抗生素骨水泥填塞后创面新鲜,诱导膜形成良好,1例经过3次抗生素骨水泥填塞后诱导膜形成良好,这5例患者二期经过植皮手术后创面均愈合良好;1例患者急诊手术时因术中血压难以维持且小腿4个间室均出现感染,急诊行膝上截肢,同时残端创面放置载抗生素骨水泥,二期骨水泥取出后创面直接闭合,创面一期愈合;②6例患者出院后随访6-24个月,末次随访时,6例患者创面均愈合良好、无红肿渗液等症状,患者生活质量明显改善,均对疗效表示满意;③对于临床高度怀疑糖尿病足坏死性筋膜炎时应警惕小腿筋膜室综合征的发生,早期诊断、及时切开减压至关重要,应用载抗生素骨水泥治疗糖尿病性坏死性筋膜炎导致的小腿筋膜室综合征短期疗效较好。

Analysis of Force Transmission by a Knee Loading Device from Skin and Soft Tissue to Knee Joint Elements

Dynamic loading to a knee joint is considered to be an effective modality for enhancing the healing of long bones and cartilage that are subject to ailments like fractures, osteoarthritis, etc. We developed a knee loading device and tested it for force application. The device applies forces on the skin, whereas force transmitted to the knee joint elements is directly responsible for promoting the healing of bone and cartilage. However, it is not well understood how loads on the skin are transmitted to the cartilage, ligaments, and bone. Based on a CAD model of a human knee joint, we conducted a finite element analysis (FEA) for force transmission from the skin and soft tissue to a knee joint. In this study, 3D models of human knee joint elements were assembled in an FEA software package (SIMSOLID). A wide range of forces was applied to the skin with different thickness in order to obtain approximate force values transmitted from the skin to the joint elements. The maximum Von Mises stress and displacement distributions were estimated for different components of the knee joint. The results demonstrate that the high load bearing areas were located on the posterior portion of the cartilage. This prediction can be used to improve the design of the knee loading device.

Integrating Test Data and ATBM Simulations into Dose Propagation Uncertainty Formulation for Bone Fracture Risk Assessment

We consider the problem of assessing bone fracture risk for a subject hit by a blunt impact projectile. We aim at constructing a framework for integrating test data and Advanced Total Body Model (ATBM) simulations into the risk assessment. The ATBM is a finite element model managed by the Joint Non-Lethal Weapons Directorate for the purpose of assessing the risk of injury caused by blunt impacts from non-lethal weapons. In ATBM simulations, the quantity that determines arm bone fracture is the calculated maximum strain in the bone. The main obstacle to accurate prediction is that the calculated strain is incompatible with the measured strain. The fracture strain measured in bending tests of real bones is affected by random inhomogeneity in bones and uncertainty in measurement gauge attachment location/orientation. In contrast, the strain calculated in ATBM simulations is based on the assumption that all bones are perfectly elastic with homogeneous material properties and no measurement uncertainty. To connect test data and ATBM simulations in a proper and meaningful setting, we introduce the concept of elasticity-homogenized strain. We interpret test data in terms of the homogenized strain, and build an empirical dose-injury model with the homogenized strain as the input dose for predicting injury. The maximum strain calculated by ATBM has randomness due to uncertainty in specifications of ATBM setup parameters. The dose propagation uncertainty formulation accommodates this uncertainty efficiently by simply updating the shape parameters in the dose-injury model, avoiding the high computational cost of sampling this uncertainty via multiple ATBM runs.

运动训练促进骨健康的研究进展

机械负荷导致适应性骨形成。这种现象涉及骨靶向重塑和适应性骨形成。骨重建对于修复机械负荷过程中产生的疲劳损伤是必要的,而适应性骨形成是提高骨刚度和强度的有效机制。因此,可以调节机械负荷的变化,从而最大程度上促进适应性骨形成。不习惯、动态、高冲击、多向、间歇性的运动,包括延长休息时间以恢复骨骼机械敏感性,是最容易促进适应性骨形成的因素。适应性骨形成可能有助于帮助运动人群预防应力性骨折。另外,充足的睡眠、补充维生素D和钙、高能量供应,可以最优化适应性骨形成。

miR-16-5p调控Wnt/β-catenin通路活性在力学载荷促进骨形成中作用的小鼠在体研究

目的 探究LRP6是否为miR-16-5p靶基因及miR-16-5p调控Wnt/β-catenin通路活性在力学载荷促进小鼠骨形成中的作用。方法 利用microRNA信息库预测miR-16-5p的靶基因,行荧光素酶报告实验来验证LRP6是否为miR-16-5p的靶基因。构建跑台组和对照组小鼠验证不同力学环境下骨组织中miR-16-5p及LRP6是否差异表达。制造miR-16-5p差异表达及力学加载动物模型:正常+miRNA Agomir control组(A组)、正常+miR-16-5p Agomir组(B组)、跑台+miRNA Agomir Control组(C组)及跑台+miR-16-5p Agomir组(D组)。干预完成后处死小鼠获取骨组织,检测各组LRP6、β-catenin及Runx2 mRNA及蛋白表达变化,行股骨远端Micro-CT扫描及股骨干生物力学测试检测骨量及力学性能变化。结果 microRNA信息库显示LRP6为miR-16-5p的可能靶基因,荧光素酶报告实验验证LRP6是miR-16-5p的靶基因。与对照组相比,跑台组小鼠骨组织中miR-16-5p表达明显降低,LRP6 mRNA表达明显升高。与A组相比,B组骨组织中LRP6、β-catenin及Runx2表达减低,骨体积分数、骨小梁厚度及生物力学性能减低。与A组相比,C组显著提高了骨组织中LRP6、β-catenin及Runx2的表达,骨体积分数、骨小梁厚度及生物力学性能均提高。与C组相比,D组结果显示LRP6、β-catenin及Runx2表达水平、骨量及生物力学性能均降低。结论 miR-16-5p能够通过靶向下调Wnt/β-catenin通路共受体中LRP6蛋白的表达而降低Wnt/β-catenin通路活性,降低小鼠骨量及骨生物力学性能,而力学载荷能够降低小鼠骨组织中miR-16-5p水平而提高LRP6蛋白表达及成骨活性和骨量。

动态四点跪位训练对脊髓损伤患者髋关节骨密度及下肢运动功能的影响

目的:探讨脊髓损伤患者进行动态四点跪位训练对髋关节骨密度及下肢运动功能的影响。方法:采用前瞻性随机对照研究方法,选取2019年1月至2022年1月收治的80例脊髓损伤患者,采用随机数字表法分为对照组与观察组各40例,对照组采用常规康复训练+直立床训练,观察组采用常规康复训练+动态四点跪位训练,两组均连续干预12周。干预前及干预4周、8周、12周时,分别记录髋关节骨密度、下肢臀大肌及腘绳肌肌电信号、感觉评分、下肢运动功能评分(LEMS),股四头肌、臀大肌及腘绳肌的肌张力(改良Ashworth分级)和肌力,并统计两组不良事件(体位性低血压、膝关节疼痛、摩擦伤、跌倒)发生情况。结果:干预4周、8周、12周时,两组髋关节骨密度T-值均低于干预前,观察组高于对照组(P<0.05);干预4周、8周、12周时,两组表面肌电信号积分肌电值及LEMS均高于干预前,且观察组高于对照组(P<0.05);干预前及干预4周、8周、12周时,两组感觉评分差异无统计学意义(P>0.05);干预4周、8周、12周时,观察组肌张力低于对照组(P<0.05),肌力高于对照组(P<0.05);两组不良事件发生率比较差异无统计学意义(P>0.05)。结论:动态四点跪位训练可以在部分负重下通过动态训练刺激髋关节周围肌肉收缩以延缓脊髓损伤患者髋关节骨量流失,改善损伤平面以下下肢运动功能,且安全性较好。

可吸收载抗菌药物硫酸钙与生物骨水泥链珠膜诱导在儿童足跟组织缺损合并创伤性跟骨骨髓炎中的效果比较

目的:探讨可吸收载抗菌药物硫酸钙与生物骨水泥链珠膜诱导在儿童足跟组织缺损合并创伤性跟骨骨髓炎中的效果。方法:选取2018年1月~2022年12月期间某院收治的96例儿童足跟组织缺损合并创伤性跟骨骨髓炎患儿作为研究对象,根据手术方式不同分为对照组(n=54)和观察组(n=42)。对照组患儿采用合理皮瓣修复后联合生物骨水泥链珠膜诱导治疗,观察组患儿采用合理皮瓣修复后联合可吸收载抗菌药物硫酸钙治疗。比较两组患儿创面分泌物细菌培养、感染性指标[肿瘤坏死因子-α(TNF-α)、白介素-6(IL-6)、白介素-8(IL-8)、白细胞计数(WBC)、红细胞沉降率(ESR)]、视觉模拟评分法(VAS)评分、住院时间、愈合时间、并发症、感染复发率及对照组患儿再次手术情况。结果:两组患儿创面分泌物细菌培养结果提示,均以金黄色葡萄球菌为主。术后7天、14天,两组患儿WBC、ESR、IL-6、IL-8、TNF-α均降低(P<0.05),且观察组低于对照组(P<0.05)。术后1、3个和6个月,两组患儿VAS评分均降低(P<0.05),观察组患儿术后1、3个月VAS评分低于对照组(P<0.05),两组患儿术后6个月VAS评分比较无统计学差异(P>0.05)。观察组患儿住院、愈合时间均短于对照组(P<0.05)。两组患儿并发症总发生率、术后6个月感染复发率比较均无统计学差异(P>0.05)。对照组患儿均需要再次手术取出骨水泥链珠,其中9例患儿再次接受骨水泥植入。结论:合理皮瓣修复后联合可吸收载抗菌药物硫酸钙治疗可更有效减轻患儿疼痛,抑制炎症反应,促进术后康复和骨愈合。

抗生素骨水泥增强胫骨横向骨搬运治疗感染创面的能力

背景:糖尿病足伴创面感染的患者群体庞大,目前尚无满意的治疗方案。目的:探讨改良胫骨横向骨搬运技术联合抗生素骨水泥治疗顽固性糖尿病足溃疡的临床疗效。方法:选择2020年1月至2023年1月首都医科大学附属北京朝阳医院和北京朝阳中西医结合急诊抢救医院收治的46例糖尿病足溃疡患者,男27例,女19例,平均年龄64.37岁,均接受改良胫骨横向骨搬运手术联合抗生素骨水泥治疗。记录胫骨横向骨搬运术前及术后3个月患者的踝肱指数、伤口/缺血/足部感染分级(WIFi分级)、目测类比评分与溃疡面积。结果与结论:①46例患者溃疡平均愈合时间为(58.07±24.82)d,46例患者胫骨横向骨搬运术后3个月的踝肱指数、目测类比评分、溃疡面积、WIFi分级均较术前明显改善(P<0.05)。随访期间,2例患者出现钉道感染,未出现溃疡或感染复发。②结果显示,改良胫骨横向骨搬运术联合抗生素骨水泥可有效缓解糖尿病足溃疡患者的疼痛、改善下肢血运、控制感染并促进溃疡的愈合。

基于传力路径的接骨板结构拓扑优化设计

目的 提出一种相对于传统拓扑优化方法能有效降低应力集中,并进一步提高断骨愈合效果的接骨板拓扑优化设计方法。方法 依据接骨板在断骨-接骨板系统中的载荷约束条件,采用改进的基于传力路径的拓扑优化方法对接骨板结构进行优化设计。随后采用基于偏应变的骨再生模拟模型,对胫骨骨干横向骨折情况进行骨再生模拟,依据骨再生过程数据对优化接骨板的受力状态、固定稳定性及愈合性能进行评估。结果 使用基于传力路径优化方法的优化接骨板在体积分数f=0.55、0.65时,接骨板最大应力分别为55.68、42.23 MPa,相较于传统拓扑优化方法优化接骨板分别降低32.96%、29.95%;骨愈合过程后骨痂平均弹性模量分别为1 439.47、1 355.71 MPa,相较于传统接骨板分别提升145.86%、131.06%。结论 提出的改进基于传力路径的拓扑优化方法,可以用于接骨板结构优化设计,优化后接骨板相比传统拓扑优化方法优化接骨板受力更加均匀,使用安全性更高,骨愈合性能相较传统接骨板有明显提升。研究结果为骨折内固定植入物的优化设计提供了一种新思路和方法。

墨鱼骨结构的力学行为及其应变率效应

墨鱼骨是一种墨鱼内部产生的生物矿化壳,通过调节壳内的气液比从而实现墨鱼的深浅浮动,同时满足轻质和高刚度的力学特性,使墨鱼能够很好地适应深海环境,所以墨鱼骨是一种典型的高比刚度的多孔材料。为探究墨鱼骨结构的力学性能,通过Instron材料试验机和分离式Hopkinson压杆实验装置,对墨鱼骨在不同加载应变率下的力学行为进行研究。研究结果表明,墨鱼骨在准静态加载下,其应力-应变曲线呈现典型的三阶段变化模式,即弹性段、平台段和压实段,具有很好地吸能缓冲作用;随着加载应变率的提高,墨鱼骨的初始压溃应力和平台应力也随之增加,表明墨鱼骨材料对加载应变率存在很强的敏感性。进一步分析不同生长方向的墨鱼骨在准静态压缩下的力学行为,结果表明随着生长方向的增加,墨鱼骨结构的刚度和吸能性能都得到了弱化,从而揭示了墨鱼骨材料压缩行为的各项异性。

前交叉韧带重建后静负载状态下骨隧道形变分析及术后效果

目的:探讨前交叉韧带重建后骨隧道扩大的现状,比较股骨偏转隧道与传统隧道的术后疗效并分析其原因。方法:选择40例前交叉韧带损伤病人,均行前十字韧带重建,其中20例病人采用偏转隧道钻取股骨隧道(偏转隧道组),余下20例病人使用传统的经前内侧入路法钻取股骨隧道(普通隧道组),术后行常规康复训练。观察病人静负载状态下骨隧道形变及雨刮效应的统计,获取骨隧道形变的力学基础和规律;比较2组IKDC评分、Lyshlom评分评估膝关节的稳定性。结果:所有病人切口均愈合良好,关节活动均恢复正常。术前,普通隧道组与偏转隧道组的IKDC评分、Lysholm评分差异均无统计学意义(P>0.05)。术后Lysholm评分、IKDC评分,2组均高于术前,且偏转隧道组均高于普通隧道组,差异均有统计学意义(P<0.05~P<0.01)。结论:股骨的偏转隧道重建可有效促进前十字韧带损伤病人的膝关节镜手术后功能恢复,预后良好。

载抗生素硫酸钙人工骨治疗股骨髓内钉感染

目的探讨载抗生素硫酸钙人工骨治疗股骨髓内钉感染的疗效。方法采用病灶清除+髓内钉取出+载抗生素硫酸钙人工骨填充+外固定架治疗37例股骨髓内钉感染患者。记录红细胞沉降率(ESR)、C-反应蛋白(CRP)、白细胞计数(WBC)以及骨折愈合时间、去除外固定架时间、膝关节AKS评分,采用Tohner-Wrnch标准评价治疗效果。结果患者均获得随访,时间10~15(13.91±0.98)个月。8例清创后骨缺损较大,术后2个月行自体髂骨植骨治疗,均愈合良好。ESR、CRP、WBC术后14 d均较术前改善,差异均有统计学意义(P<0.01)。骨折愈合时间3~7(4.93±0.98)个月,去除外固定架时间6~9(7.35±0.93)个月。末次随访时,膝关节AKS评分由术前70~85(78.53±4.02)分提高至140~153(147.03±4.03)分,差异有统计学意义(P<0.05);采用Tohner-Wrnch标准评价疗效:优25例,良8例,可4例,优良率89.19%。结论载抗生素硫酸钙人工骨治疗股骨髓内钉感染,能有效控制髓内感染,具有良好的生物相容性且能诱导成骨,治疗效果满意。

非对称加强与狗骨式削弱型钢框架节点抗震性能数值模拟

为有效防止梁柱节点处发生脆性破坏并提高节点抗震性能,提出一种非对称加强与狗骨式削弱型钢框架节点。以边柱节点为例,利用ABAQUS有限元软件对非对称加强与狗骨式削弱型节点、非对称加强型节点、狗骨式削弱型节点和普通型节点共4个节点模型进行抗震性能对比分析,研究了节点的破坏形态、滞回曲线、骨架曲线、延性、耗能能力和刚度退化等方面的区别。研究表明:非对称加强与狗骨式削弱型节点能够有效实现塑性铰外移,防止节点发生脆性破坏,同时不仅能够提高节点的耗能能力和延性,还可以保持较好的承载能力。