Residual stress effects on fracture energies of cement-bone and cement-implant interfaces

The effects of residual stresses, which are caused by the temperature difference arising after polymerisation of bone cement, on the fracture energies of cement bone and cement-implant interfaces have been examined by using both experimental and numerical works. Only fracture loads of the test specimen having interfacial cracks have been measured in the experimental stage. The values of fracture loads and temperature difference after polymerisation have been applied to finite element models of the test specimens to calculate critical J-integral values of these both interfaces in the numerical stage. In addition, fracture energies of bone and cement, have been obtained by experimentally, using three-point bending test method The results have shown that residual stresses can produce changes in the fracture energies of these bimaterial systems, especially in cement implant interface and J(Ic) values of interfaces are considerably smaller than the experimentally determined J(Ic) values of cement and bone.     

骨质疏松影响股骨近端防旋髓内钉治疗股骨转子间骨折的有限元仿真

文题释义：骨质疏松：是骨量减少导致骨微结构破坏、进而易发生骨折的全身性疾病,它不仅是导致髋部骨折的重要原因之一,也是导致股骨近端防旋髓内钉内固定失效的重要原因之一。 股骨转子间骨折：在老年人中较为常见,现主要是手术治疗,股骨近端防旋髓内钉被广泛应用于临床。股骨转子间骨折内固定术后失效时有发生,其原因可能与骨质疏松、骨折类型、尖顶距值、复位质量等密切相关。 背景：股骨近端防旋髓内钉治疗股骨转子间骨折在临床应用广泛,但仍有部分术后内固定失效病例,股骨近端骨质疏松被认为是一个重要原因。Singh指数是评价股骨近端骨质疏松严重程度的一个重要指标,基于Singh指数探讨不同骨质疏松程度对股骨近端防旋髓内钉治疗转子间骨折疗效的影响,对减少内固定失效概率,增加手术成功率具有重要意义。 目的：探讨不同骨质疏松程度对股骨近端防旋髓内钉治疗转子间骨折疗效的影响,为临床治疗转子间骨折提供新思路和实验基础。 方法：选取1例左侧股骨转子间骨折患者的CT资料,导入Mimics 19.0和Geomagic studio 2017软件中进行提取、优化得到右侧股骨三维模型。运用Solidworks 2017软件画出内固定模型并与股骨模型按照标准手术技术装配,以STEP格式导入Hypermesh 14.0软件中截骨得到AO 2.1型股骨转子间骨折模型,参照Singh指数1-6划分应力骨小梁得到A-F模型,设置材料属性参数、边界条件、施加载荷,分别储存为K文件导入LS-DYNA软件求解。 结果与结论：①当股骨头受力时,Singh 6-Singh 1股骨头颈骨块中螺旋刀片产生切割,普通骨小梁消失,包裹螺旋刀片的应力骨小梁不但没有消失,且承载和分散了部分应力,使得螺旋刀片仍具有较大的接触面积和把持力,维持着骨折的复位,减少了股骨头颈骨块的内翻和旋转;②从Singh 6-Singh 1,随着应力骨小梁的消失,骨质疏松越严重,股骨近端防旋髓内钉治疗股骨转子间骨折就越容易失效;③股骨近端海绵状的丰厚骨小梁,特别是应力骨小梁,通过抵抗、缓冲弯曲应变而在维持股骨的弹性稳定起着重要作用,是股骨近端弹性稳定的重要结构。 ORCID: 0000-0002-4097-2790(黄培镇) 中国组织工程研究杂志出版内容重点：人工关节;骨植入物;脊柱;骨折;内固定;数字化骨科;组织工程     

手掌骨折内外固定器之刚度比较

为了比较微型内固定器和微型外固定器的机械强度，本实验以材质均匀的枫木空管模拟手部小骨，植入（１）Ａｅｓｃｕｌａｐ微型外固定器（２）微型Ａ－Ｏ接骨板（３）交叉钢针及（４）自制骨水泥外固定器。并设计（１）横截断面（２）断面留２ｍｍ间隙及（３）４５°斜切来模拟稳定性骨折、不稳定性骨折及螺旋型骨折。在ＩＮＳＴＲＯＮ材料试验机分别做张力、扭力及弯曲负荷测试。实验资料经统计之变异数分析（ＡＮＯＶＡ）及成对资料分析（Ｔｕｋｅｙｐａｉｒｗｉｓｅｃｏｍｐａｒｉｓｏｎ），发现在不同的骨折断面中，张力刚度均以微型接骨板最好（Ｐ＜０．００１）。侧弯刚度以置放在背面的微型接骨板最好。在稳定和不稳定骨折时，扭力刚度以Ａｅｓｃｕｌａｐ的微型外固定器最好（Ｐ＜０．０１），但在４５°斜切断面时，扭力刚度以微型接骨板最好（Ｐ＜０．００１）。在稳定性骨折时，微型接骨板（背面或侧面）与微型外固定器的前弯刚度较好，但没有明显差异。在不稳定性骨折和４５°斜切时，前弯刚度以侧面骨板和微型外固定器较好。除了扭力刚度以外，Ａｅｓｃｕｌａｐ微型外固定器和自制骨水泥外固定器并无明显差异。而如预期的，交叉钢针的机械强度是最弱的（Ｐ＜０．０１...更多）。     

3D Finite Element Analysis of a Man Hip Joint Femur under Impact Loads

Objective： The biomechanical characters of the bone fracture of the man femoral hip joint under impact loads are explored. Methods ：A biosystem model of the man femoral hip joint by using the GE （ General Electric） lightspeed multi-lay spiral CT is conducted. A 3D finite element model is established by employing the finite element software ANSYS. The FE analysis mainly concentrates on the effects of the impact directions arising from intense movements and the parenchyma on the femoral hip joint on the stress distributions of the proximal femur. Results：The parenchyma on the hip joint has relatively large relaxation effect on the impact loads. Conclusion：Effects of the angle δ of the impact load to the anterior direction and the angle γ of the impact load to the femur shaft on the bone fracture are given;δ has larger effect on the stress and strain distributions than the angle γ,which mainly represents the fracture of the upper femur including the femoral neck fracture when the posterolateral femur is impacted, consistent with the clinical resuits.     

Bone Loss Among Women Living With HIV

Clinical data accumulated over the past two decades attests to a significant decline in bone mineral density (BMD) in patients infected by HIV, which does not remit but may actually intensify with anti-retroviral therapy (ART). Long generally perceived as an aberration without clinical consequences in relatively young HIV-infected cohorts, recent studies have documented marked increases in fracture incidence in HIV-infected men and women over a wide age continuum. Fractures are associated with chronic pain, crippling morbidity, and increased mortality, undermining the gains in quality of life achieved though ART. As bone loss and resulting increases in fracture incidence are a natural consequence of aging, there is now concern regarding the long-term consequences of HIV/ART-associated premature bone loss, given the transition of the HIV/AIDS population into an older age demographic. The development of guidelines for diagnosis and treatment of bone disease within the context of HIV and ART has been an important recent step in raising awareness of the problem and the implications of bone fracture for patient health. Significant progress has also been made in recent years in dissecting the complex and multifactorial mechanisms driving bone loss in HIV/ART and the role of underlying immunological disruption in skeletal dysmorphogenesis. This review examines recent progress in the field and studies by Women’s Interagency HIV Study (WIHS)-associated investigators, inside and outside of the WIHS cohort, aimed at identifying skeletal abnormalities, quantifying facture incidence, management, and understanding underlying mechanisms in people living with HIV in the context of chronic ART.     

Interface shear strength and fracture behaviour of porous glass-fibre-reinforced composite implant and bone model material

Glass-fibre-reinforced composites (FRCs) are under current investigation to serve as durable bone substitute materials in load-bearing orthopaedic implants and bone implants in the head and neck area. The present form of biocompatible FRCs consist of non-woven E-glass-fibre tissues impregnated with varying amounts of a non-resorbable photopolymerisable bifunctional polymer resin with equal portions of both bis-phenyl-A-glycidyl dimethacrylate (BisGMA) and triethyleneglycol dimethacrylate (TEGDMA). FRCs with a total porosity of 10-70 vol% were prepared, more than 90 vol% of which being functional (open pores), and the rest closed. The pore sizes were greater than 100?μm. In the present study, the push-out test was chosen to analyse the shear strength of the interface between mechanically interlocked gypsum and a porous FRC implant structure. Gypsum was used as a substitute material for natural bone. The simulative in vitro experiments revealed a significant rise of push-out forces to the twofold level of 1147 ±?271?N for an increase in total FRC porosity of 43%. Pins, intended to model the initial mechanical implant fixation, did not affect the measured shear strength of the gypsum-FRC interface, but led to slightly more cohesive fracture modes. Fractures always occurred inside the gypsum, it having lower compressive strength than the porous FRC structures. Therefore, the largest loads were restricted by the brittleness of the gypsum. Increases of the FRC implant porosity tended to lead to more cohesive fracture modes and higher interfacial fracture toughness. Statistical differences were confirmed using the Kruskal-Wallis test. The differences between the modelled configuration showing gypsum penetration into all open pores and the real clinical situation with gradual bone ingrowth has to be considered.     

Conceptual finite element study for comparison among superior,anterior, and spiral clavicle plate fixations for midshaft clavicle fracture

Open reduction internal fixation technique has been generally accepted for treatment of midshaft clavicle fractures. Both superior and anterior clavicle plates have been reported in clinical or biomechanical researches, while presently the spiral clavicle plate design has been introduced improved biomechanical behavior over conventional designs. In order to objectively realize the multi-directional biomechanical performances among the three geometries for clavicle plate designs, a current conceptual finite element study has been conducted with identical cross-sectional features for clavicle plates. The conceptual superior, anterior, and spiral clavicle plate models were constructed for virtual reduction and fixation to an OTA 15-B1.3 midshaft transverse fracture of clavicle. Mechanical load cases including cantilever bending, axial compression, inferior bending, and axial torsion have been applied for confirming the multi-directional structural stability and implant safety in biomechanical perspective. Results revealed that the anterior clavicle plate model represented lowest plate stress under all loading cases. The superior clavicle plate model showed greater axial compressive stiffness, while the anterior clavicle plate model performed greater rigidity under cantilever bending load. Three model represented similar structural stiffness under axial torsion. Played as a transition structure between superior and anterior clavicle plate, the spiral clavicle plate model revealed comparable results with acceptable multi-directional biomechanical behavior. The concept of spiral clavicle plate design is worth considering in practical application in clinics. Implant safety should be further investigated by evidences in future mechanical tests and clinical observations.     

镍钛合金冠脉支架纵向柔顺性数值分析

目的利用有限元方法分析自主设计镍钛合金冠脉支架的结构特征与纵向柔顺性的关系。方法通过Soildworks设计一种新型支架的几何模型,运用Hypermesh、MATLAB及ABAQUS软件构建出支架的有限元模型,在ABAQUS中对支架一个结构周期内的9个弯曲方向上分别施加转角位移,使支架保持纯弯曲状态。结果支架柔顺性在自接触前差异性不明显;当自接触发生后,支架的柔顺性表现出明显的各向异性,同时支架在平面内的纯弯曲载荷作用下发生弯曲变形,并伴随着平面外的偏转及围绕自身轴线的扭转变形。结论支架的结构特征决定了其弯曲行为,连接体的螺旋和自接触使支架的柔顺性始终表现出各向异性,为支架在临床上的应用提供科学指导。     

Mechanical Evaluation of Large-Size Fourth-Generation Composite Femur and Tibia Models

Composite analogue bone models provide consistent geometric and structural properties that represent a valuable asset in a range of biomechanical analyses and testing procedures. The objective of this study was to evaluate the diaphyseal structural properties of the large-size Fourth-Generation composite analogue femur and tibia models concentrated on mechanical behaviors under axial compression, bending and torsion. Thirty of each large-size composite analogue models (femora and tibiae) were tested under medial-lateral four-point bending, anterior-posterior four-point bending, axial compression and external rotational torque to evaluate flexural rigidity, axial stiffness, torsional rigidity and ultimate failure strength. The composite femur was tested under torsion at both the femoral neck and the mid-diaphyseal areas. Large-size Fourth-Generation composite replicate bones exhibited intra-specimen variations under 10% for all cases and was also found to perform within the biological range of healthy adult bones (age: <80 years old) range with respect to flexural rigidity (<8%) and torsional rigidity (<12%). The failure modes of these composite models were close to published findings for human bones (four-point bending: butterfly fragment fracture; torsional: spiral fracture; and compression: transverse fracture). The large-size composite analogue femur and tibia are close to ideal replicas for standardization in biomechanical analyses. One advantage of these analogue models is that their variability is significantly lower than that of cadaveric specimens for all loading regimens. Published results vary widely in cadaveric studies, which is likely due to the high anatomic variability among cadaveric specimens. This study evaluated and advanced our overall understanding of the capacity of composite analogue bone models mimic the structural properties of average healthy adult human bones.     

基于不同应变判定准则模拟皮质骨断裂的准确性

文题释义：基于等效应变断裂模拟：即在大鼠股骨皮质骨断裂模拟过程中，应用皮质骨有限元模型在外部载荷作用下所产生的等效应变数值，与皮质骨组织的失效应变进行对比，当等效应变数值大于皮质骨组织失效应变时，有限元模型内的单元便发生失效，直至失效单元达到一定数量，模型便发生整体失效，此过程为基于等效应变的断裂模拟。 基于主应变断裂模拟：即在大鼠股骨皮质骨断裂模拟过程中，应用皮质骨有限元模型在外部载荷作用下所产生的主应变数值，与皮质骨组织的失效应变进行对比，当主应变数值大于皮质骨组织失效应变时，有限元模型内的单元便发生失效，直至失效单元达到一定数量，模型便发生整体失效，此过程为基于主应变的断裂模拟。 背景：由于意外碰撞等外力因素所产生的皮质骨裂纹是引起骨折的重要原因之一，要防止此类骨折发生，首先需弄清不同载荷作用下皮质骨裂纹的产生与扩展机制。由于实验分析对样本具有破坏性，难以同时了解骨结构在断裂前后的内部力学状态，找到一种能够准确模拟皮质骨从裂纹产生、扩展，直至断裂过程的有限元方法就显得尤为重要。当前模拟方法主要应用主应变或等效应变判定模型单元力学状态，继而进行断裂模拟，却鲜有关于这2种应变进行模拟准确性的探究。 目的：验证应用主应变与等效应变进行皮质骨断裂模拟的准确程度。 方法：结合实验与仿真分析，应用主应变与等效应变进行皮质骨断裂模拟，将仿真与实验结果进行对比，确定应用哪种应变进行模拟更加准确。 结果与结论：①应用主应变模拟的皮质骨断裂时间要明显晚于应用等效应变；②通过与实验对比发现，相比主应变，应用等效应变进行仿真所得结果与实验值更为接近；③因此，应用等效应变进行皮质骨断裂模拟相对更加准确。 ORCID: 0000-0003-0313-1359(王伟军) 中国组织工程研究杂志出版内容重点：人工关节；骨植入物；脊柱；骨折；内固定；数字化骨科；组织工程     

Analysis of miniature single- and double-notch bending specimens for estimating the fracture toughness of cortical bone

Studies of the fracture behavior of cortical bone have determined multiple toughening mechanisms that are active during propagation of a crack. Common methods for measuring bone fracture toughness use single-notched specimens often in four-point (SN4PB) or three-point bending (SN3PB). A double-notch four-point bending (DN4PB) specimen is useful to study prefailure damage at the crack tip. Total failure occurs at one notch and only partial failure at the other allowing study of prefailure damage in the unbroken notch. There is no widely known method for calculating the fracture toughness of bone using a DN4PB specimen. A method for calculating the fracture toughness of cortical bone using a DN4PB is developed here and compared with results for a common SN3PB specimen. The new double-notch method permits using a single specimen to measure apparent fracture toughness and to study both pre- and postfailure microdamage in the bone matrix. When and how to use the new and the established test specimens for understanding bone mechanics is discussed.     

骨折内固定接骨板破坏原因分析与实验研究

临床用接骨板内固定骨折,在骨折愈合过程中钢板发生破坏现象时有发生,我们应用静强度理论模拟人体单肢站立承受太弯组合变形,在人体新鲜尸体下肢人为造成骨折,用接骨板固定。对接骨板进行应变测量,还对接骨板进行疲劳实验、四点弯曲实验。用静强度理论和低周疲劳劳强度理论分析接骨板的破坏原因,旨在为设计应用接骨板提供理论依据。     

保留前纵韧带的椎体间植骨术的稳定性实验研究

目的：为评价保留前纵韧带的椎体间支撑植骨治疗脊柱爆裂骨折提供的生物力学稳定能力。方法：用传感器及电测技术，采用新鲜人体胸腰段脊柱标本。结果：除旋转外，轴压、前屈、后伸、侧弯四种运动方式皆能提供满意的稳定性。结论：实验提示，该方法能明显增加损伤脊柱的力学稳定性，有利于提高脊柱的融合率，是一种治疗脊柱骨折较为理想的植骨方法     

糖皮质激素对大鼠股骨及腰椎的生物力学影响

目的：从生物力学角度研究ＧＣ对大鼠皮质和松质骨的影响。方法：采用３月龄♂ＳＤ大鼠１９只,随机分为基础对照组、年龄对照组和激素模型组后者灌喂醋酸泼尼松４．５ｍｇ／ｋｇ,２次／周。３个月后取股骨和第３～５腰椎行股骨干的扭转、三点弯曲和腰椎的压缩试验。结果：激素模型组与年龄对照组比较,股骨干在三点弯曲试验时所随的载荷减少了１７．１％（Ｐ〈０．０５）,无椎弓的椎体压缩试验时所随的载荷减少了２９．９％（Ｐ〉     

回收扩髓产物自体移植促进下肢长骨干骨折愈合*

背景：扩髓产物中具有多种促进骨折愈合成分,有助于骨折早期组织愈合及骨再生。 目的：观察扩髓产物促进下肢长骨干骨折愈合的临床治疗效果。 方法：回顾合肥市第二人民医院2008-01/2010-11应用扩髓带锁髓内钉治疗下肢长骨干骨折病例78例,其中采取开放复位利用扩髓产物回植者38例,而采取闭合复位者40例。 结果与结论：两组患者下肢长骨干骨折处均出现愈合。应用扩髓产物回植的患者出现骨痂、骨折线模糊及消失的时间均早于闭合复位的患者(P < 0.05)。提示应用带锁髓内钉的同时采用扩髓产物自体移植能促进下肢长骨干骨折愈合。     

骨的疲劳损伤和修复

骨是人体承担力学功能的器官，习惯性生理运动范围内中等应力／应变水平就能引起骨的疲劳损伤，激烈运动甚至引起骨折。骨疲劳损伤的实质是骨基质上产生比典型裂纹更小的裂纹，此种裂纹也可能出现在胶原和羟基磷灰石晶体水平，但骨能对基质损伤进行修复，即对损伤区的骨质吸收，然后替换新骨质，骨细胞通过损伤的细胞突和调整性细胞死亡发出骨损伤基质吸收的信号骨细胞在骨基质损伤修复过程中起重要的作用。骨的疲劳和修复是骨的一种生理现象，研究者们把此过程用数学，力学模型定量化描述，以达到对骨生理过程更深的认识及临床实践更好的应用。     

骨折不愈合的诊断及治疗建议

骨折的愈合是一个复杂的过程,能否成功愈合取决于多种内源和外源因子,愈合过程中的一些因素改变往往导致骨折的延迟愈合甚至骨不连。骨不连的发生率在5%～10%之间,随着严重损伤患者数量增多,骨不连发生率亦在随之增加。骨不连有很高的社会经济负担,主要是由间接成本造成的,如由于治疗时间长而造成的生产力损失。近年来,对于骨不连发病的影响因素、诊断及治疗方式的研究加深了外科医师对骨不连的认识。随着对骨不连认识的不断深入,外科医师对骨折的早期处理也进行了改善,从而降低了骨不连发生的风险,另外对骨不连本身的处理方式也得以进一步改良。本文的目的即在于回顾目前已发表的文献,以期增加临床医师对骨不连这一骨折并发症的认识以及为临床上选择恰当合理的治疗方法提供参考。     

16层螺旋CT后处理技术在鼻区外伤中的应用

目的：探讨16层螺旋CT对鼻区外伤诊断的临床应用价值。方法：选取2003-2008年在我科检查的150例患者,分为正常（其他原因行头颅扫描）和鼻区外伤患者,行16层螺旋CT检查,进行各种重建,并结合源图像分析。结果：正常鼻骨形态可分两型（Ⅰ型、Ⅱ型）,鼻尖部游离缘可见两型（A型、B型）;复合骨折最多见,占63例,单纯鼻骨骨折占37例;讨论：16层螺旋CT重建可以细致的显示鼻区解剖结构。对鼻区复合骨折的部位、程度及伴发改变全面观察。结论：多层螺旋CT及后处理技术在鼻区的运用,影像解剖清晰、立体、直观,诊断明确,更为客观科学,是目前对鼻区骨折诊断的先进的影像诊断方法。对于临床诊断、治疗有指导意义,有助于疑难病例的确诊、防止漏诊及误诊,而且有助于整复手术方案的设计更为合理可取,并且解决了法医学鉴定的相关问题,具有一定的社会意义     

闭合AO空心螺钉治疗Jones骨折

目的总结闭合AO空心螺钉固定治疗第五跖骨基底部Jones骨折15例的临床疗效。方法回顾分析2008年6月~2010年9月采用闭合AO空心螺钉治疗Jones骨折15例的临床资料。结果 15例获得3~8个月随访,骨折均愈合,平均愈合时间2~3.5个月,功能恢复良好,按Maryland足部评分系统评分,优8例,良5例,可2例,优良率达86.7%。结论闭合AO空心螺钉固定治疗Jones骨折具有创伤小,固定牢靠,对软组织破坏少,有利于踝关节功能恢复等优点,是治疗Jones骨折的有效方法。     

Effects of geometry on fracture initiation and propagation in all-ceramic crowns

The complex and patient-unique geometry of posterior all-ceramic dental crowns represents a particularly interesting set of challenges to understanding stress concentration and fracture evolution in response to loading. A series of numerical and physical experiments, with both single cycle and fatigue loading, show that geometry profoundly influences the stress concentration and fracture initiation and propagation. In stylized crowns with uniform axial wall height, stresses concentrate beneath the indenter. As the height of the axial wall increases, loads to cause failure increase linearly. In crowns with variation in axial wall height around the periphery, stresses concentrate both beneath the indenter and at the margin of the core ceramic. The magnitude of the stress concentration at the margin is directly related to the amount of variation in axial wall height around the periphery of the crown. Anatomically correct veneered zirconia core crowns subjected to single-cycle loads, fracture in areas of greatest stress concentration identified by finite element models. Fractures and stress concentrations that occur in response to single-cycle loading are important indicators of initiation sites for fatigue failure. (c) 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2009.