新型人工椎间盘

美国AcroMed公司开发的这种新型人工椎间盘已由美国Lutheran医学中心首次植入人体,继后美国FDA批准第二代椎间盘假体在多个中心进行临床试验。 这种人工装置由用商业纯钛多孔涂层的     

人工腰椎间盘置换研究应用进展

椎间盘病变是脊柱外科的常见疾病,是成年人疼痛和致残的常见原因,常常给人带来沉重的肉体和经济负担。经过长时间的发展与脊柱外科手术的进步,常规手术治疗在临床上虽然取得了一定的疗效,但是没有保留脊柱的生理运动功能,对临近阶段的椎间盘的退变起到促进作用,并且腰椎运动节段的融合加快了邻近节段椎间盘和小关节的退变。腰椎独特的解剖学特点和生物力学的研究及不同材质和特点的人工椎间盘材料的发展使人工椎间盘手术成为可能。与常规手术方式相比,人工椎间盘假体设计与人生理的解剖结构更加吻合。术后可以保持瞬时和长期的稳定性,从而对邻近的椎间盘的退变起到抑制作用。取得了较好的疗效。人工椎间盘置换术作为治疗腰椎间盘除腰椎融合之外的另一合理选择,目的是使退变导致的疼痛可以稳定长期缓解,并重建椎间隙高度以保护神经,从而避免晚期关节突关节及邻近节段的病变,恢复脊柱的运动学和载荷特性。目前人工腰椎间盘有了长远的发展,适应症不断扩大,但仍有较多限制。期待在将来能够找出更加符合人体生物力学特点的材料和设计,使之成为一种更为有效的治疗腰椎疾病的治疗方式。现就人工椎间盘的类型、疗效、适应证、禁忌证以及术后并发症等方面予以综述。     

哈萨克族成人腰稚间盘高度的放射学测量及其临床意义

目的：为人工椎间盘的设计提供形态学依据。方法：对56例哈萨克族成人腰椎（L）间盘高度进行放射学测量。结果：56例哈萨克族L1-2椎间盘高度男女性之间差异无统计学意义（P〉0．05）,L3-5椎间盘高度男、女性之间差异有统计学意L（P〈0．005-0．001）;哈萨克族与汉族腰椎间盘高度之间差异均有统计学意义（P〈0．005）。结论：哈萨克族腰椎间盘高度均大于汉族,临床上可通过对腰椎间盘间高度的测量,为人工椎间盘假体设计提供参数．     

人体椎间盘蠕变力学模型和理论分析

本文提出了人体椎间盘的压缩蠕变力学模型。并且应用二相多孔弹性理论，对蠕变力学模型进行了理论分析。其椎间盘压缩蠕变位移公式应为Wf=a.h.p用此式计算与文献上的实验结果相接近，此外还证明了，椎间盘退化较正常椎间盘的蠕变速率为大。     

人工肘关节的生物力学分析

本文对人体肘关节进行了生物力学分析,对人工肘关节进行了具体的力学计算与分析试验,为人工肘关节设计和临床治疗提供了依据。     

Bryan人工椎间盘置换术治疗颈椎病的研究进展

Bryan人工椎间盘置换术是治疗颈椎椎间盘退行性变的有效手段,与传统的颈前路植骨融合内固定术比较,颈椎人工椎间盘置换的最大优势在于在有效减压的同时重建节段的运动功能,使整个颈椎运动学特征最大程度地接近于置换前的生理状态,减少传统融合术后由于融合节段运动功能丧失所造成的相邻节段过度运动和应力集中,从而避免相邻节段退变的发生和发展.但没有统一的适应症标准、缺乏远期的临床观察、昂贵的费用等问题阻碍了其在临床上的广泛应用,该文着重进行颈椎人工椎间盘的生物力学特点、适应症与禁忌症、临床疗效以及并发症的文献综述.     

人工髋关节光弹实验研究

为了满足治疗关节炎和关节外伤的需要,七十年代世界各国已有几百种全髋假体设计作为定型产品应用于临床。然而人工关节研究面临着两大问题尚待解决。一为人工假体的生物匹配。所谓“生物匹配性”即是考虑植入人体之假体对人体的适应性,也就是假体材料应对人体无毒性,不引起变态反应和异常的新陈代谢,没有致癌性,对组织没有刺激性等等。二为人工假体的力学匹配,这要求假体有足够的抗拉强度和抗压强度以及适当的韧性,还要求疲劳强度和耐磨性,以及泡浸在血液、间质液、淋巴液、关节润滑液中的耐腐蚀性。人工关节的研究已成为医师和工程师共同关心和相互协作的间题。     

几何形人工膝治疗类风湿性关节炎初探

对于类风湿性关节炎引起的膝关节破坏和强直,开始我们采用铰链型人工膝关节,大约70%的病人获得满意的结果。然而,在实践中发现这种关节存在某些缺点:1)金属与金属之间的耐磨性能差;2)不能模拟正常膝在最后伸直时伴有的旋转运动,可造成假体松动;3)晚期感染率较高。因此,从1982年2月起,我们开始采用几何形人工膝。假体设计的改进假体采用上海手术器械六厂生产的钴铬钼——聚乙烯几何形人工膝(见图1)。设计时     

区域生态安全格局研究进展

如何构建一个安全的区域生态格局,对土地可持续利用和区域生态安全有重要意义。区域生态安全格局的构建需要多学科的综合、多角度的分析和多种实现手段的结合,一般从景观格局优化、土地资源优化配置和景观恢复等途径入手,构建结构合理、功能高效、关系协调的区域生态安全模式。在分析国内外相关研究进展的基础上,对区域生态安全格局构建在数量优化、空间优化和综合优化等方法进行了总结,在此基础上提出了构建区域生态安全格局的思路：区域生态现状评价、情景预案与目标设定、区域生态安全格局设计、方案实施及其效果评价、方案调整与管理。未来区域生态安全格局研究的趋势表现为：空间优化模型的进一步改进;区域生态安全标准量化的探索;注重公众参与机制和不同组织水平利益相关者的协调。     

法研制人工椎间盘

法国医务人员和国家原子能委员会新近共同研制成功一种由聚合物和钛制成的人造椎间盘。目前,研究人员正在测试其寿命,并计划在两年内正式投入临床使用。 该项目负责人菲利普·拉贝表示,研制人造椎间盘的目的是用它取代椎间盘突出症患者受损的纤维软骨,彻底解除这些患者的病痛。他介绍说,这种人造椎间盘的中心部分是由聚     

Characterization and Optimization of Orodispersible Mosapride Film Formulations

Orodispersible film (ODF) technology offers new possibilities for drug delivery by providing the advantages of oral delivery coupled with the enhanced onset of action and convenience to special patient categories such as pediatrics and geriatrics. In this study, mosapride (MOS) was formulated in an ODF preparation that can be used for treatment of patients who suffer from gastrointestinal disorders, especially difficulty in swallowing due to gastroesophageal reflux disease. Poloxamer 188 was used to solubilize MOS to allow its incorporation into the film matrix. The films were prepared by solvent-casting method using different polymer ratios of maltodextrin and hydroxypropyl methylcellulose and plasticizer levels of glycerol and propylene glycol. A D-optimal design was utilized to study the effect of polymer ratio, plasticizer type, and level on film mechanical properties, disintegration time, and dissolution rate. Statistical analysis of the experimental design showed that the increase of maltodextrin fraction and plasticizer level conferred optimum attributes to the prepared films in terms of film elasticity, film disintegration time, and MOS release rate. The ODF formulations were further tested for moisture sorption capacity, with formulations containing a higher ratio of maltodextrin and percent plasticizer showing more moisture uptake. The optimum film composition was also tested in vivo for film palatability and disintegration time. An optimized mosapride orodispersible film formulation was achieved that could be of benefit to patients suffering from gastrointestinal disorders.     

Numerical investigations of the mechanical properties of a braided non-vascular stent design using finite element method

This paper discusses various issues relating to the mechanical properties of a braided non-vascular stent made of a Ni–Ti alloy. The design of the stent is a major factor which determines its reliability after implantation into a stenosed non-vascular cavity. This paper presents the effect of the main structural parameters on the mechanical properties of braided stents. A parametric analysis of a commercial stent model is developed using the commercial finite element code ANSYS. As a consequence of the analytical results that the pitch of wire has a greater effect than other structural parameters, a new design of a variable pitch stent is presented to improve mechanical properties of these braided stents. The effect of structural parameters on mechanical properties is compared for both stent models: constant and variable pitches. When the pitches of the left and right quarters of the stent are 50% larger and 100% larger than that of the central portion, respectively, the radial stiffness in the central portion increases by 10% and 38.8%, while the radial stiffness at the end portions decreases by 128% and 164.7%, the axial elongation by 25.6% and 56.6% and the bending deflection by 3.96% and 10.15%. It has been demonstrated by finite element analysis that the variable pitch stent can better meet the clinical requirements.     

Experimental study and constitutive modeling of the viscoelastic mechanical properties of the human prolapsed vaginal tissue

In this paper, the viscoelastic mechanical properties of vaginal tissue are investigated. Using previous results of the authors on the mechanical properties of biological soft tissues and newly experimental data from uniaxial tension tests, a new model for the viscoelastic mechanical properties of the human vaginal tissue is proposed. The structural model seems to be sufficiently accurate to guarantee its application to prediction of reliable stress distributions, and is suitable for finite element computations. The obtained results may be helpful in the design of surgical procedures with autologous tissue or prostheses.     

Mechanical properties of single hyaluronan molecules

Hyaluronan (HA) is a major component of the extracellular matrix. It plays an important role in the mechanical functions of the extracellular matrix and stabilization of cells. Currently, its mechanical properties have been investigated only at the gross level. In this study, the mechanical properties of single HA molecules were directly measured with an optical tweezer technique, yielding a persistence length of 4.5 +/- 1.2 nm. This information may help us to understand the mechanical roles in the extracellular matrix infrastructure, cell attachment, and to design tissue engineering and drug delivery systems where the mechanical functions of HA are essential.     

Versatile and inexpensive Hall-Effect force sensor for mechanical characterization of soft biological materials

Mismatch of hierarchical structure and mechanical properties between tissue-engineered implants and native tissue may result in signal cues that negatively impact repair and remodeling. With bottom-up tissue engineering approaches, designing tissue components with proper microscale mechanical properties is crucial to achieve necessary macroscale properties in the final implant. However, characterizing microscale mechanical properties is challenging, and current methods do not provide the versatility and sensitivity required to measure these fragile, soft biological materials. Here, we developed a novel, highly sensitive Hall-Effect based force sensor that is capable of measuring mechanical properties of biological materials over wide force ranges (μN to N), allowing its use at all steps in layer-by-layer fabrication of engineered tissues. The force sensor design can be easily customized to measure specific force ranges, while remaining easy to fabricate using inexpensive, commercial materials. Although we used the force sensor to characterize mechanics of single-layer cell sheets and silk fibers, the design can be easily adapted for different applications spanning larger force ranges (>N). This platform is thus a novel, versatile, and practical tool for mechanically characterizing biological and biomimetic materials.     

Microstructure and mechanical properties of rostrum in Cyrtotrachelus longimanus (Coleoptera: Curculionidae)

The microstructure, composition and mechanical properties of the rostrum in Cyrtotrachelus longimanus (JHC Fabre) were studied utilizing light, fluorescent, scanning electron microscopy (SEM) and energy-dispersive spectroscopy. SEM images show the morphological characteristics of rostrum’s cross section; it is a typical lightweight multilayer structure – one rigid exocuticle layer and dense endocuticle layers, which construct unevenly overlapping fiber structures. The composition analysis of the rostrum shows that it is mainly composed of C, H, N, O, as well as some metal elements and microelements, such as Mg, Si, Zn, Ca and Na, which contribute to its mechanical performance. The mechanical properties of the rostrum were tested by the electronic universal testing machine, which shows it has high-specific strength and is almost the same as that of the stainless steel. The results may provide a biological template to inspire biomimetic lightweight structure design.     

Cuttlebone: Characterisation, Application and Development of Biomimetic Materials

Cuttlebone signifies a special class of ultra-lightweight cellular natural material possessing unique chemical,mechanical and structural properties,which have drawn considerable attention in the literature.The aim of this paper is to better understand the mechanical and biological roles of cuttlebone.First,the existing literature concerning the characterisation and potential applications inspired by this remarkable biomaterial is critiqued.Second,the finite element-based homogenisation method is used to verify that morphological variations within individual cuttlebone samples have minimal impact on the effective mechanical properties.This finding agrees with existing literature,which suggests that cuttlebone strength is dictated by the cuttlefish habitation depth.Subsequently,this homogenisation approach is further developed to characterise the effective mechanical bulk modulus and biofluidic permeability that cuttlebone provides,thereby quantifying its mechanical and transporting functionalities to inspire bionic design of structures and materials for more extensive applications.Finally,a brief rationale for the need to design a biomimetic material inspired by the cuttlebone microstructure is provided,based on the preceding investigation.     

Modeling of mechanical properties and structural design of spider web

With a unique combination of strength and toughness among materials, spider silk is the model for engineering materials. This paper presents the stress-strain behavior of Nephila clavipes spider silk under tension, transverse compression, and torsional deformation obtained by a battery of micro testing equipment. The experimental results showed significantly higher toughness than the state-of-the-art fibers in tension and in transverse compression. Higher shear modulus was also observed for the spider silk comparing to other liquid crystalline fibers such as aramid fibers. On the basis of the experimental results finite element analysis is used to simulate static and dynamic properties of spider web and to explore the role of both material properties and architectural design in its structural integrity and mechanical performance.     

The mechanical behaviour of cancellous bone

Cancellous bone has a cellular structure: it is made up of a connected network of rods and plates. Because of this, its mechanical behaviour is similar to that of other cellular materials such as polymeric foams. A recent study on the mechanisms of deformation in such materials has led to an understanding of how their mechanical properties depend on their relative density, cell wall properties and cell geometry. In this paper, the results of this previous study are applied to cancellous bone in an attempt to further understand its mechanical behaviour. The results of the analysis agree reasonably well with experimental data available in the literature.     

Numerical design of a microfluidic chip for probing mechanical properties of cells

Microfluidic chips have been widely used to probe the mechanical properties of cells, which are recognized as a promising label-free biomarker for some diseases. In our previous work (Ye et al., 2018), we have studied the relationships between the transit time and the mechanical properties of a cell flowing through a microchannel with a single constriction, which potentially forms a basis for a microfluidic chip to measure cell’s mechanical properties. Here, we investigate this microfluidic chip design and examine its potential in performances. We first develop the simultaneous dependence of the transit time on both the shear and bending moduli of a cell, and then examine the chip sensitivity with respect to the cell mechanical properties while serializing a single constriction along the flow direction. After that, we study the effect of the flow velocity on the transit time, and also test the chip’s ability to identify heterogeneous cells with different mechanical properties. The results show that the microfluidic chip designed is capable of identifying heterogeneous cells, even when only one unhealthy cell is included. The serialization of chip can greatly increase the chip sensitivity with respect to the mechanical properties of cells. The flow with a higher velocity helps in not only promoting the chip throughput, but also in providing more accurate transit time measurements, because the cell prefers a symmetric deformation under a high velocity.