非融合棘突间固定器不同棘突间撑开高度对植入节段椎间盘压力分布的影响

背景：腰椎退变性疾病目前的非融合内固定特别是棘突间固定理论上可以保留有益活动,在缓解疼痛的同时预防邻近节段退变。 目的：测量棘突间不同的撑开程度情况下节段椎间盘负荷分担及应力分布情况。 方法：新鲜成人腰椎标本L_2~5,采用电子万能实验机模拟腰椎前屈、中立、后伸运动负荷。实验分为7组：正常脊柱组,形状记忆合金棘突间固定器支撑高度10,12,14,16,18,20 mm组。 结果与结论：支撑高度为10 mm的形状记忆合金棘突间固定器对植入节段椎间盘的压力分布无显著性影响;支撑高度为12 mm的形状记忆合金棘突间固定器在过伸时可分担46%的椎间盘后纤维环负荷(P < 0.05);支撑高度为14 mm的形状记忆合金棘突间固定器可维持植入节段的轻度前屈,在过伸时可分担约47%的后环负荷(P < 0.05),但后伸时会增大前环的负荷,当支撑高度远大于植入节段中立位时的棘突间高度时,屈伸活动时,后环的负荷显著降低的同时,前环负荷可增大达400%。提示支撑高度等于或略大于中立位棘突间高度的非融合棘突间固定器可分担椎间盘负荷并使椎间盘应力更均匀分布;但支撑高度过大会明显增大前环的负荷,如果用于神经源性间歇性跛行患者的椎间孔撑开,可能会加快椎间盘的退变。     

国产新型腰椎棘突间撑开器体外生物力学测试及有限元分析

文题释义： 三维有限元分析：运用计算机三维模型,从结构、形态、弹性模量上模拟人体腰椎屈伸、侧弯、轴向旋转活动,通过应力云图直观显示在不同位置棘突间撑开器、椎体植入节段及临近节段的应力分布及腰椎活动度等情况。有限元分析只是一种模拟实验,因此其对该装置的评价需要结合动物实验和临床观察,才能更接近实际。 体外生物力学：是应用力学原理和方法对生物体中力学问题定量研究的生物物理学分支。随着生物力学在医学领域的不断发展,运用生物力学来检测新设计的脊柱内固定器械的生物特性已成为一项必经程序。体外生物力学实验试件通常选择的是内固定器械与实验标本共同组成的标本单元。采用此形式对测试物体进行脊柱屈伸、侧弯和侧旋等生理载荷模式下的力学测试,可更加精确、方便和准确地获得内固定器械特性参数,与三维有限元分析相辅相成。 背景：腰椎棘突间撑开器非融合系统为腰椎退行性疾病提供了一种新的治疗选择。但目前国内临床对于腰椎棘突间撑开系统的应用及研究严重不足,对于适用于国人的国产化腰椎棘突间撑开器更是鲜有报道。 目的：通过人体腰椎三维有限元分析技术和山羊腰椎体外生物力学实验分析国产新型棘突间撑开器生物力学特点,验证新型腰椎棘突间撑开器的科学性和有效性。 方法：①国产新型腰椎棘突间撑开器有限元分析：通过正常成人腰椎CT资料建立L₂-L₅椎体三维模型,随后依次建立国产新型腰椎棘突间撑开器模型、国产新型腰椎棘突间撑开器腰椎非融合系统模型,赋予腰椎生理情况下的力学条件,对新型撑开器植入前后进行生物力学分析;②国产新型腰椎棘突间撑开器体外生物力学分析：获取24只成年雄性山羊腰椎(L₁-L₅),在L_3-4棘突间植入国产新型腰椎棘突间撑开器,撑开器植入前后检测腰椎标本前屈、后伸、侧弯、旋转状态下的腰椎活动度与椎间盘压力。 结果与结论：①在撑开器植入后,责任节段后伸时活动范围及椎间盘压力减小,相邻节段活动度和椎间盘压力几乎不受影响,从理论上验证了腰椎棘突间撑开器可以为腰椎退行性疾病的治疗提供了生物力学依据,为预防临椎病贡献了理论参考。②在后伸状态下,L_3-4椎体植入撑开器后的椎体活动度明显小于植入前(P < 0.05),L_2-3、L_4-5椎体植入撑开器后的椎体活动度与植入前比较差异无显著性意义(P > 0.05);在前屈、侧弯、旋转状态下,L_2-3、L_3-4、L_4-5椎体植入撑开器后的椎体活动度与植入前比较差异均无显著性意义(P > 0.05)。在后伸状态下,L_3-4椎体植入撑开器后的椎间盘压力明显小于植入前(P < 0.05),L_2-3、L_4-5椎体植入撑开器后的椎间盘压力与植入前比较差异无显著性意义(P > 0.05);在前屈、侧弯、旋转状态下,L_2-3、L_3-4、L_4-5椎体植入撑开器后的椎间盘压力与植入前比较差异均无显著性意义(P > 0.05)。③结果表明,国产新型腰椎棘突间撑开器的科学性和有效性均从三维有限元分析和体外动物腰椎标本实验得到了有力验证,为国产新型棘突间撑开器的活体动物实验、临床实验、临床应用以及临床生产提供了有力的依据。 ORCID: 0000-0001-6432-9794(王宝东) 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     

新型棘突间撑开融合装置BacFuse修复腰椎退行性病的生物力学特征

背景：近年来,棘突间撑开融合装置BacFuse应用于腰椎退行性疾病的治疗并取得了良好的临床疗效,但目前其相关的生物力学特征暂无相关报道。目的：探索棘突间撑开融合装置BacFuse在腰椎退行性疾病中应用的生物力学特征。方法：构建山羊离体脊柱模型(L₁-L₆),模拟手术分为4组,分别为对照组、BacFuse固定组(L_3/4)、钉棒固定组(L_3/4)及Topping-off组(L_3/4钉棒固定+L_2/3 BacFuse固定)。搭建山羊腰椎手术模型力学测试系统,采用生物力学机器进行力学加载,模拟腰椎在前屈、后伸、侧屈及旋转时的运动模式(4 Nm的力矩),采用视觉追踪系统进行定位捕捉,并完成力学及光学校准,通过计算得出L_2/3、L_3/4、L_4/5节段的活动度。结果与结论：(1)相对于对照组,BacFuse组L_3/4固定节段在前屈、后伸、侧屈与旋转方向上活动度分别减少27.27%,...     

腰椎关节突结构差异影响腰椎退变机制的生物力学研究现状

<正>腰椎退行性病变导致的腰腿痛是当今社会造成劳动力丧失和残疾的常见原因之一,严重影响患者的生活质量,产生了巨大的医疗费用支出。腰椎关节突关节作为腰椎应力传导和运动控制的重要部分,其复杂的解剖结构和生物力学特点决定其在腰椎退变过程中起到了重要作用。关节突结构差异可能通过对关节突退变和椎间盘退变的影响进而加速腰椎整体退变的进程。通过影像学观察发现,这种差异与部分腰椎退行性病变的发生存在相关性[1-6],提示关节突结构差异通过特殊的     

经椎间孔腰椎椎间融合结合不同椎弓根螺钉固定在单节段腰椎及邻近节段的生物力学特征

文题释义： 生物力学：是应用力学原理和方法对生物体中的力学问题定量研究的生物物理学分支,分为体外和体内生物力学。体外生物力学实验通常将测试的内固定器械与动物标本共同组成的标本单位,采用此形式对离体标本进行脊柱屈伸、侧弯和旋转等生理载荷模式下的力学测试,可更加精确、方便和准确地获得内固定器械稳定性的指标参数。 经椎间孔椎间融合内固定术：通过切除部分关节突关节扩大椎间孔,行椎体间减压植骨,再给予椎弓根钉棒系统来增加椎体间稳定性,促进骨性融合。该入路不需要过度牵拉硬膜和走形神经根,减少硬膜和神经根的副损伤,同时保留了脊柱后方韧带复合体增加稳定性。 背景：对于腰椎退行性病变,早期给予有效固定达到椎间融合可重建脊柱稳定性,所以减压-固定-融合是脊柱外科手术的关键。 目的：比较经椎间孔腰椎椎间融合术下双侧椎弓根螺钉固定、单侧椎弓根螺钉固定、单侧椎弓根螺钉固定联合经对侧椎板小关节固定融合节段与邻近节段的生物力学稳定性。 方法：选用18具新鲜小牛L_3-5标本,在经椎间孔腰椎椎间融合术下进行不同的固定形式,分成A组(完整标本)、B组(双侧椎弓根螺钉固定)、C组(单侧椎弓根螺钉固定)、D组(单侧椎弓根螺钉固定联合经对侧椎板小关节固定),分别测试邻近节段L_3-4、融合节段L_4-5在后伸、前屈、左侧弯、右侧弯、左旋转、右旋转6个方向上的活动范围值及融合节段L_4-5的刚度值。 结果与结论：①对于融合节段L4-5的活动范围,B组6个方向的稳定性最高;D组次之,并在旋转方面与B组有相似结果(P > 0.05);C组右侧弯和左旋转的稳定性不足,关节活动度与A组比较差异无显著性意义(P > 0.05);A组6个运动方向的活动度最大,稳定性最差;②对于融合节段L4-5的刚度值,B组6个方向的刚度值最大,与其他组比较差异均有显著性意义(P < 0.05);C组和D组左、右旋转下的刚度值比较差异有显著性意义(P < 0.05),A组6个运动方向的刚度值最低;③对于临近节段L3-4的活动范围,B组6个方向的活动范围最大,邻近节段承受负荷最大,同其他3组比较差异有显著性意义(P < 0.05);D组除左、右旋转外其余方向的活动范围同C组、A组比较差异无显著性意义(P > 0.05);C组和A组6个方向活动范围比较差异均无显著性意义(P > 0.05);④结果表明,单侧椎弓根螺钉固定早期在右侧弯和左旋转方向的活动度大,接近于完整标本组,存在稳定性不足的缺点,临床中需要慎用并严格把握适应证。单侧椎弓根螺钉联合对侧经椎板关节突螺钉固定技术改进了单侧椎弓根螺钉不对称固定的弊端,增加了旋转和侧弯的稳定性,又可以避免双侧椎弓根螺钉固定对邻近节段的影响,可以成为临床的一种有效手术治疗方式。 ORCID: 0000-0002-2810-2047(侯继春) 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     

腰椎棘突间非融合植入物的特点及生物力学特性

背景：非融合技术可以避免椎间盘髓核摘除和脊柱融合固定治疗椎退行性病变导致的椎间盘丧失原有的生物力学功能或加剧蜕变。 目的：总结各种腰椎棘突间非融合植入物特点、疗效及置入后生物力学的变化。 方法：作者检索1990/2012 PubMed数据库及中国知网数据库检索与腰椎棘突间非融合植入物治疗脊柱退行性病变的相关研究。 结果与结论：共纳入31条文献。棘突间非融合植入物能撑开病变节段棘突间隙,防止过度后伸,从而增加相应水平椎管横截面积和椎间孔高度,降低椎间盘负荷和小关节负荷,控制异常活动,保持运动功能来预防邻近节段退变,使失稳的腰椎达到正常状态的活动特性,实现动态重建腰椎序列。腰椎棘突间植入物可根据其特性及作用特点分为静态和动态两类,分别以X-STOP和Coflex为代表。由于不同的腰椎棘突间非融合植入物具有不同的特点,因而适应症状有所不同,应通过鉴别患者的不同发病原因,选择最合适的棘突间非融合器械进行个体化治疗,使其植入后更加符合生理情况应力分布。关键词：腰椎棘突间非融合植入物;腰椎退行性病变;生物力学;医学植入物;组织工程 doi:10.3969/j.issn.1673-8225.2012.17.036     

腰椎关节突关节融合：从植骨融合到螺钉和融合器的应用

背景：腰椎关节突关节是脊柱后柱的重要结构,其固定与融合在腰椎后路手术被广泛应用。 目的：阐述了各种腰椎关节突关节融合技术的优缺点和疗效。 方法：应用计算机检索PubMed数据库、CNKI数据库中有关腰椎关节突关节融合方法的文献。 结果与结论：传统的关节突关节融合方法为关节突关节V形开槽,然后植入松质骨,不需要作大范围的剥离,创伤小,所需植骨量较少,融合率高,缺点是即刻的稳定性较差。经关节突关节螺钉固定联合横突间融合可以提高植骨融合率,但存在融合失败、术后症状缓解不明显、螺钉松动和断裂、硬膜撕裂、螺钉穿刺到椎管引起神经损伤等并发症。圆柱体嵌入椭圆体的融合器有利于融合器与关节面充分的接触,同时提高了融合器的稳定性和抗移位能力。目前对腰椎关节突关节融合的研究远没有对后外侧融合的研究那么充分,系统的生物力学研究和中远期临床疗效及并发症的研究有待深入研究。     

下腰椎L4/5棘突间撑开器的生物力学研究

应用有限元分析方法研究在L4/5植入X STOP类型产品时该节段的稳定性,以及对相邻节段的生物力学影响。依据一名正常志愿者中立位下螺旋CT扫描资料,利用Mimics14、Geomagic Studio2012、Hypermesh12和Abaqus612 1等软件,构建L2～L5健康腰椎有限元模型和植入撑开器X STOP的动态固定模型,并模拟前屈、后伸、侧弯和轴向旋转,验证健康腰椎有限元模型的有效性和动态固定对照模型的生物力学特性。根据两组模型在椎间活动度、椎间盘应力等生物力学指标,证明X STOP可减少该节段7483%的后伸活动度,而相邻节段活动度基本不受影响。植入物和腰椎的最大应力出现在后伸时两者的接触面上,最大应力分别为333和1356 MPa。X STOP可以显著降低椎间盘压力和后伸活动度,对相邻阶段无明显影响。植入物和腰椎的最大von Mises应力出现在接触面上。对X STOP的改进提供理论支持,为下腰椎L4/5棘突间撑开器X STOP临床手术提供生物力学依据。     

后路椎间融合器对不同节段腰椎稳定性的影响

目的:探讨后路椎间融合器对L4~5、L5~S1节段稳定性的影响。方法:采用6具无脊柱疾患的尸体脊柱标本(L1～S5),利用最大载荷为10Nm的力偶对其中L4~5、L5~S1节段的完整状态、腰椎不稳状态、双侧小关节切除1/3、1/2或全切除 Cage固定等5种状态进行前屈、后伸,左、右侧弯和左、右轴向旋转运动试验,而后进行统计学处理。结果:对于L4~5节段,双侧小关节切除1/3、1/2或全切除后,加后路椎间融合器前屈、左右侧弯运动范围较完整均显著降低,分别为4.50±2.43、2.61±0.82、3.21±1.41,4.70±1.47、3.43±0.75、4.13±0.81,5.98±2.67、3.89±0.70、4.53±1.33(P<0.01);对于L5~S1节段,在双侧小关节内侧分别切除1/3时,后路椎间融合器能降低其前屈、右侧弯运动范围,分别为4.70±2.50、2.32±0.99(P<0.01);切除1/2小关节时,其前屈运动范围降低,为6.02±2.15(P<0.05);但切除全部小关节时,前屈、后伸、左侧弯、右侧弯和左轴向旋转运动范围降低,分别为2.59±0.27、2.69±1.10、1.08±0.76、1.02±0.69(P<0.01)和1.15±0.30(P<0.05)。结论:后路螺纹椎间融合器对L4~5、L5~S1节段均有一定的稳定作用,但其对前者的稳定作用更为明显;在L5-S1节段应用后路螺纹椎间融合器时,小关节切除不能超过1/3,否则,必须附加后路器械固定。     

X-STOP棘突间撑开器治疗腰椎退行性疾病的中期临床疗效

目的:探讨X-STOP棘突间撑开器治疗腰椎退行性疾病的中期临床疗效.方法:2008年1月～2011年3月,我院采用X-STOP棘突间撑开器治疗腰椎退行性疾病患者30例,其中男12例,女18例;记录并比较术前、术后及末次随访患者的腰腿痛情况、腰椎间活动度、椎间盘高度.结果:平均随访(2.9±1.23) a.术后患者腰腿痛明显缓解;JOA评分、ODI评分与椎间高度术后及末次随访数据与术前比较,差异有统计学意义(P﹤0.05);终板夹角术后及末次随访数据与术前比较,差异均无统计学意义(P＞0.05).结论:正确选择合适的病例,X-STOP棘突间撑开器治疗腰椎退行性疾病的中期临床疗效满意.     

The effects of a new shape-memory alloy interspinous process device on the distribution of intervertebral disc pressures in vitro

This study was designed to measure the pressure distribution of the intervertebral disc under different degrees of distraction of the interspinous process, because of a suspicion that the degree of distraction of the spinous process may have a close relationship with the disc load share. Six human cadaver lumbar spine L2-L5 segments were loaded in flexion, neutral position, and extension. The L3-L4 disc load was measured at each position using pressure measuring films. Shape-memory interspinous process implants (SMID) with different spacer heights, ranging in size from 10 to 20 mm at 2 mm increments, were used. It was found that a SMID with a spacer height equal to the distance of the interspinous process in the neutral position can share the biomechanical disc load without a significant change of load in the anterior annulus. An interspinous process stabilizing device (IPD) would not be appropriate to use in those cases with serious spinal stenosis because the over-distraction of the interspinous process by the SMID would lead to overloading the anterior annulus which is a recognized cause of disc degeneration.     

Biomechanical analysis of a new lumbar interspinous device with optimized topology

Interspinous spacers used stand-alone preserve joint movement but provide little protection for diseased segments of the spine. Used as adjuncts with fusion, interspinous spacers offer rigid stability but may accelerate degeneration on adjacent levels. Our new device is intended to balance the stability and preserves motion provided by the implant. A new interspinous spacer was devised according to the results of topology optimization studies. Four finite element (FE) spine models were created that consisted of an intact spine without an implant, implantation of the novel, the device for intervertebral assisted motion (DIAM system), and the Dynesys system. All models were loaded with moments, and their range of motions (ROMs), peak disc stresses, and facet contact forces were analyzed. The limited motion segment ROMs, shielded disc stresses, and unloaded facet contact forces of the new devices were greater than those of the DIAM and Dynesys system at L3-L4 in almost all directions of movements. The ROMs, disc stresses, and facet contact forces of the new devices at L2-L3 were slightly greater than those in the DIAM system, but much lower than those in the Dynesys system in most directions. This study demonstrated that the new device provided more stability at the instrumented level than the DIAM system did, especially in lateral rotation and the bending direction. The device caused fewer adjacent ROMs, lower disc stresses, and lower facet contact forces than the Dynesys system did. Additionally, this study conducted topology optimization to design the new device and created a smaller implant for minimal invasive surgery.     

In vitro interaction of human fibroblasts and platelets with a shape-memory polyurethane

Physicochemical and mechanical properties, in vitro cytotoxicity, cytocompatibility, and platelet adhesion were investigated on a shape-memory polyether-based polyurethane (MM-5520 SMPu) using the polyether-based Pellethane 2363-80AE (Pell-2363 SPU) as reference. MM-5520 SMPu and Pell-2363 SPU showed similar average molecular weights and different surface properties, with a higher hydrophilicity and roughness for the SMPu. By tensile tests and dynamic mechanical analysis, the peculiar characteristics of the MM-5520 SMPu were evidenced: strong temperature-dependent behavior for SMPu compared with SPU, and a high shape recovery. MM-5520 SMPu did not show any cytotoxic effect on the adhesion and proliferation of human skin fibroblasts and gingival fibroblasts, and a good cytocompatibility was observed with both cell types, as demonstrated by cell counting and scanning electron microscopy observations. SMPu compared with SPU showed higher adsorption of extracellular matrix proteins such as fibronectin, fibrinogen, and collagens. Proteins adsorbed onto SMPu significantly enhanced the adhesion and proliferation of human fibroblasts. The interaction of SMPu with platelets was studied with platelet rich plasma. Fewer platelets adhered to the SMPu, with minor morphological variations than onto the SPU. The cytocompatibility and hemocompatibility of MM-5520 SMPu combined with its unique properties such as change in shape or in stiffness, depending on practical requirements, make this shape-memory material potentially advantageous for biomedical applications.     

An annulus fibrosus closure device based on a biodegradable shape-memory polymer network

Injuries to the intervertebral disc caused by degeneration or trauma often lead to tearing of the annulus fibrosus (AF) and extrusion of the nucleus pulposus (NP). This can compress nerves and cause lower back pain. In this study, the characteristics of poly(d,l-lactide-co-trimethylene carbonate) networks with shape-memory properties have been evaluated in order to prepare biodegradable AF closure devices that can be implanted minimally invasively. Four different macromers with (d,l-lactide) to trimethylene carbonate (DLLA:TMC) molar ratios of 80:20, 70:30, 60:40 and 40:60 with terminal methacrylate groups and molecular weights of approximately 30 kg mol⁻¹ were used to prepare the networks by photo-crosslinking. The mechanical properties of the samples and their shape-memory properties were determined at temperatures of 0 °C and 40 °C by tensile tests- and cyclic, thermo-mechanical measurements. At 40 °C all networks showed rubber-like behavior and were flexible with elastic modulus values of 1.7–2.5 MPa, which is in the range of the modulus values of human annulus fibrosus tissue. The shape-memory characteristics of the networks were excellent with values of the shape-fixity and the shape-recovery ratio higher than 98 and 95%, respectively. The switching temperatures were between 10 and 39 °C. In vitro culture and qualitative immunocytochemistry of human annulus fibrosus cells on shape-memory films with DLLA:TMC molar ratios of 60:40 showed very good ability of the networks to support the adhesion and growth of human AF cells. When the polymer network films were coated by adsorption of fibronectin, cell attachment, cell spreading, and extracellular matrix production was further improved. Annulus fibrosus closure devices were prepared from these AF cell-compatible materials by photo-polymerizing the reactive precursors in a mold. Insertion of the multifunctional implant in the disc of a cadaveric canine spine showed that these shape-memory devices could be implanted through a small slit and to some extent deploy self-sufficiently within the disc cavity.     

Coflex棘突间固定装置在治疗腰椎管狭窄症中的价值

目的　评价Coflex棘突间固定装置治疗腰椎管狭窄症的应用价值。 方法　回顾性分析临床随访期＞5年的手术治疗腰椎管狭窄症患者115例,其中Coflex组54例,融合组61例。比较两组围手术期指标及术前和末次随访时JOA、ODI、VAS、 SF-36评分;比较两组术前及末次随访时邻近节段椎间活动度增加量、椎间隙高度丢失量及Pfirrmann 分级评定。 结果 两组间临床观察指标无统计学差异（P>0.05）。两组椎间活动度增加量对比无统计学差异（P>0.05）;融合组椎间隙高度丢失量较Coflex组明显（P<0.01）;融合组相邻节段椎间盘Pfirrmann分级进展较Coflex组明显（P<0.05）。 结论　Coflex植入术和融合术临床疗效相当,并能延缓影像学上的邻近节段病变。     

In vitro and in vivo studies on a Mg-Sr binary alloy system developed as a new kind of biodegradable metal

Magnesium alloys have shown potential as biodegradable metallic materials for orthopedic applications due to their degradability, resemblance to cortical bone and biocompatible degradation/corrosion products. However, the fast corrosion rate and the potential toxicity of their alloying element limit the clinical application of Mg alloys. From the viewpoint of both metallurgy and biocompatibility, strontium (Sr) was selected to prepare hot rolled Mg-Sr binary alloys (with a Sr content ranging from 1 to 4 wt.%) in the present study. The optimal Sr content was screened with respect to the mechanical and corrosion properties of Mg-Sr binary alloys and the feasibility of the use of Mg-Sr alloys as orthopedic biodegradable metals was investigated by in vitro cell experiments and intramedullary implantation tests. The mechanical properties and corrosion rates of Mg-Sr alloys were dose dependent with respect to the added Sr content. The as-rolled Mg-2Sr alloy exhibited the highest strength and slowest corrosion rate, suggesting that the optimal Sr content was 2 wt.%. The as-rolled Mg-2Sr alloy showed Grade I cytotoxicity and induced higher alkaline phosphatase activity than the other alloys. During the 4 weeks implantation period we saw gradual degradation of the as-rolled Mg-2Sr alloy within a bone tunnel. Micro-computer tomography and histological analysis showed an enhanced mineral density and thicker cortical bone around the experimental implants. Higher levels of Sr were observed in newly formed peri-implant bone compared with the control. In summary, this study shows that the optimal content of added Sr is 2 wt.% for binary Mg-Sr alloys in the rolled state and that the as-rolled Mg-2Sr alloy in vivo produces an acceptable host response.     

In vitro model for studying the effects of hemodynamics on device induced thromboembolism in human blood

Biomateria related thromboembolism is a complex phenomenon, affected by such variables as biomaterial surface chemistry, hemodynamics, and individual donor variations. Thus, isolation of the individual variables would greatly facilitate the understanding and inhibition of this phenomenon. A low volume in vitro model with this potential has been developed, with the initial focus on studying the influence of hemodynamics on thromboembolism (TE) in human blood. Patterned after a larger in vitro model for bovine blood used successfully in our laboratory, the smaller model directed fresh human blood in a single pass through 1/32 inch ID PVC tubing and a flow cell at 3 ml/min. The flow cell consisted of alternating abrupt expansions and contractions of cylindrical tubing that could be modified to study the effects of hemodynamic parameters on TE. Thrombus growth in the flow cell was monitored visually by transillumination microscopy. Emboli from the flow cell were detected continuously by a light-scattering microemboli detector (LSMD), and their strength was assessed by using the constant-pressure filtration (CPF) method. Preliminary studies confirmed the potential of this model. Thrombi were observed visually in the flow cell at sites of high vorticity and at flow separation and reattachment points and were also observed to embolize. Emboli were detected by the LSMD downstream of the flow cell in significantly greater numbers than upstream and were coincident with the embolization of thrombi observed visually. Emboli collected downstream of the flow cell occluded the CPF filters at 50 mm Hg, suggesting that they possessed sufficient strength to occlude microvessels. This model may be used to aid in developing a computer model of thromboembolism, which could subsequently be refined with clinical data.     

磁悬浮离心式心室辅助装置的体外溶血测试**

背景：心室辅助装置已广泛应用于心力衰竭患者的治疗。虽然有不同的血泵在国外应用于临床,却很少在国内应用,主要原因是其价格太高。因此在国内研制相对价格较低的能应用于临床的自主血泵迫在眉睫。 目的：测试置入式磁悬浮离心心室辅助装置主体血泵的溶血性能。 方法：通过计算流体力学方法,对磁悬浮离心式心室辅助装置主体血泵内部流场做初步分析。血泵在后负荷100 mm Hg     (1 mm Hg=0.133 kPa)、流量5 L/min 情况下,通过体外模拟血循环系统驱动羊血测试血泵体外溶血性能,计算血泵实际标准溶血指数NIH。 结果与结论：在设计工况下计算流体力学结果显示血泵内部流线平稳,整个流道内部壁面剪切力均在68.5 Pa以下,内部静压力分布均匀,过渡平稳,没有不良区域出现。体外溶血实验测得标准溶血指数NIH值为(0.075±0.017) mg/L。提示血泵驱动叶片及内部流道设计合理,同第3代血泵相比有较好溶血性能。血泵实验期间无不良状况发生,可以进行下一步长期的动物体内实验,进而评估血泵体内血流动力学性能和血泵置入对实验动物脏器的影响。