我们想感谢的材料和结构测试核心设施和工程在梅奥诊所司的技术支持。此外，我们想感谢劳伦斯 J.殷勤，詹姆斯 · 布朗，布兰特纽曼，Jorn op den Buijs，博士学位，他们在研究期间的帮助。这项研究提供了由格兰杰基金会从固安捷创新基金资助。

1.大型夹具附件 <ol><li>从机器中删除标准夹具。</li>
	<li>移动十字头分开以适应内部夹具。</li>
	<li>将铝块 （在 图 1A 部分号 1） 放在机器上和牢固地扣上使用两个螺栓机; 在中心孔可容纳机负载细胞。</li>
	<li>在铝块上放置主要夹具结构 （在 图 1B 第第 2 部分） 和安全地将它附加到块中使用 4 根螺栓。</li>
	<li>放置四吨杰克下不休息在铝块支持夹具 ( 图 1) 的夹具的一部分。</li>
	<li>在主要夹具上装载 6 信道负载细胞夹具 （ 图 1 中的部分号 3） 和安全使用 6 螺钉。</li>
</ol> 2。十字头夹具附件 <ol><li>将机十字头设置为使用十字头电梯控制的绝对零。</li>
	<li>第一基板 ( 图 2B 中的部件号 4) 重视十字头 7 螺钉用其面对的试验机前面的曲边。</li>
	<li>附加第二基板 （在 图 2 中的部件号 5） 使用一个旋转螺杆。螺丝在测试过程中容纳了左、 右的骨头。第二基板 (部件号 5) 可以自由旋转枢轴螺钉相对于第一基板 (部件号 4) 有关。第二底板的方向确定安装是否为右侧或左侧股骨。</li>
	<li>连接两个幻灯片轴承 （ 图 2D 中的部分 6 号） 第二基板 (部件号 5) 使用 4 个螺钉 （从第一基板的一侧，就可以访问两个螺钉） 的大会。旋转方式可以从第一滑床板的顶部螺丝第二套第二基板。 
	注意: 若要更改幻灯片的方向从左骨对骨，在第一基板上的四颗螺丝都松开，并对幻灯片进行旋转枢轴螺钉和再紧固在所需方向。</li>
	<li>通过将机十字头设置为 65 ° 的相对位置手动旋转幻灯片正交 6 信道负载细胞。</li>
</ol> 3。检测夹具、 高速摄像机和灯光设置实验 <ol><li>套仪器的底部夹具标准伺服液压试验机。此夹具将举行股骨和容纳左和右股骨在秋天对髋关节的配置 ( 图 1)。</li>
	<li>设置高速相机和照明设备 ( 图 3A-3D)。
	<ol><li>与机器两侧各一个三脚架上定位高强度灯光和确保它们 ( 图 3A)。</li>
		<li>为高速相机两侧的测试机和每个摄像机连接到数据采集单元 （ 图 3B -3 C） 设置三脚架。</li>
		<li>与照相机上并连接到采集单元，配置相机设置; 设置帧速率为 6000 帧 / 秒 (fps) 和分辨率为 1,024 x 512 像素; 可以降低分辨率来容纳相机内部内存 (图 3D)。</li>
		<li>集快门到 1 帧/秒 (1/6,000 fps)。此外设置相机选项，这样录音开始之前作动器移动 (100 ms 快速测试和慢测试 200 毫秒)。</li>
		<li>将两者之间的同步电缆连接相机; 在相机的软件设置中选择触发模式。</li>
	</ol></li></ol> 4。检查/标定加载细胞为适当的数据采集系统 (DAQ) <ol><li>数据采集单元设置 <ol><li>连接到测试数据采集机、 高速摄像机、 测压元件和布线中所示的线性电位器原理 图 4 中。</li>
		<li>检查正确的连接的股骨粗隆部负载细胞，磁头加载单元，线性电位器，6 信道负载细胞，并触发信号到 DAQ 设备通过观察数据信号痕迹在视图面板中的数据采集软件，通过手动推负载细胞。</li>
		<li>验证数据采集、 信号调理和脉冲发生器是所有动力。</li>
		<li>配置从负载细胞和线性电位器的所有信号的数据采集软件。在数据采集软件，选择 &#34; 一步安装 &#62; &#62; 配置 &#34; 选项卡，然后为每个与每个负载单元格关联的信号输入设置采集频率 （赫兹）。对 &#34; 触发 &#34; 选项卡上，选择适当的触发选项。视频设备也应触发期间试运行，以确保视频/数据采集系统同步性。</li>
	</ol></li> <li>额定负载 （例如至少 200 磅，最大限度地 1600 磅） 适用于股骨头和使用标准伺服液压机器验证合理负载的转子负荷细胞细胞测量和比较对制造商校准数据单 ( 图 5A)。</li>
	<li>同样，不适用于静荷载作用下 6 信道负载细胞通过使用一片死寂，如 图 5B 所示。检查功能和验证 6 信道负载电池的性能 ( 图 5A -5B) 通过计算实测和理论的力和力矩值之间的百分比差异。误差应小于 5%。 
	注: 所有负载细胞必须被都校准由其制造商提前。这一步只检查负载细胞运作、 进行所有的连接和信号是合理的。</li>
	<li>校准线性电位器 <ol><li>安全到十字头线性电位器夹具和线性电位器置于夹具 （ 图 5）。拧紧螺钉锁电位器身体和连接器插入数据采集单元</li>
		<li>手动移动 （25 毫米） 致动器上负荷帧，使电位器位置从最大压缩转换最大扩展和记录位移和相对应的电压 （至少三个数据点）。情节与电压位移和拟合数据的线性函数 (R 2 &#62; 0.95)。输入的线性方程 (m m/V) 边坡作为校正因子成 &#34; 缩放参数 &#34; 框中的数据采集软件。</li>
	</ol></li> <li>验证总体测试机安装测试代理玻璃纤维骨骨折以确保所有的数据采集功能和合理。这包括转子负荷细胞、 股骨头部测压元件、 线性电位器、 六信道负载细胞，触发信号 ( 图 6)。</li>
</ol> 5。准备测试的骨头 <ol><li>解冻在室温下 24 h 的骨头和去除水分，多余的脂肪和任何剩余的软组织使用 pa每毛巾。</li>
	<li>骨置于扫描夹具，丙烯酸和制备牙科水泥。计量 60 克 PMMA 粉和混合液体树脂在通风橱下 30 克直到粉溶解为止。混合物应浇注。为这一进程使用一次性纸杯。这一步是为灌封股骨大转子在铝杯 ( 图 7A)。</li>
	<li>对齐低于转子铝杯。然后在此基础上，倒到高度的杯中，一半的 PMMA 水泥，提高夹具平台以适合骨进杯子里。允许为聚合的 10-15 分钟。</li>
	<li>包骨头在生理盐水中的浸泡过的毛巾在骨水泥聚合期间避免组织干燥。</li>
	<li>移动到中铝杯附加到转子 ( 图 7B) 试验机测试夹具的骨</li>
	<li>中心铝杯上板附加到股骨粗隆部负载单元格，并调整幻灯片轴承，铝杯略有触动的负载单元格。从夹具旋转夹具的允许删除 pin</li> <li>中心和低与股骨头接触十字头。</li>
	<li>审查安装、 骨位置、 负载细胞信号和杯位置。此外审查 DAQ 设备;确保所有设备和负荷的细胞连接正确，并验证所有已通电。检查软件设置为适当的信号响应从每个负载细胞。</li>
	<li>股骨拍照放在从 2 面夹具。</li>
	<li>设置光圈使足够的光线到相机传感器和控制领域的深度。通过专注于股骨颈检查图像质量。这一过程应防止任何眩光和光泽骨区域图像中会影响捕获骨折事件。</li>
</ol> 6。测试到骨折 <ol><li>验证伺服机械负荷框架编程为 25 毫米的断裂试验伺服机械负荷框架中加载和卸载的适当位移控制。 
	注意: 这些是制造商特定的设置应输入和验证在控制面板的测试设备根据制造商规格。</li>
	<li>验证照明，以尽量减少反射在视频摄像机和数据采集系统，最后一次。</li>
	<li>单击开始图标从控制面板启动测试序列断裂试验股骨 ( 图 7)。</li>
	<li>从 2 边治疗股骨骨折拍照。</li>
	<li>手动收回作动器和从机删除股骨。</li>
</ol> 7。后骨折制备 <ol><li>骨去除夹具。</li>
	<li>磁带断的近端的骨轴、 包裹在湿的毛巾和塑料袋 ( 图 7)，并然后冻结在-20 ° C.</li>
	<li>保留进一步后骨折的 x 线及 CT 成像骨头。 
	注: 详细介绍了为这些进程已经从我们组 （审查在朱庇特） 以前解释在另一种协议 ( 图 7E)。</li>
</ol>

<ol><li>Bouxsein, M. L., Szulc, P., Munoz, F., Thrall, E., Sornay-Rendu, E., Delmas, P. D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Contribution+of+trochanteric+soft+tissues+to+fall+force+estimates%2C+the+factor+of+risk%2C+and+prediction+of+hip+fracture+risk%5BTitle%5D)+AND+%22J+Bone+Miner+Res%22%5BJournal%5D)">Contribution of trochanteric soft tissues to fall force estimates, the factor of risk, and prediction of hip fracture risk.</a> J Bone Miner Res. 22, 825-831 (2007).</li>
<li>Rezaei, A., Dragomir-Daescu, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Femoral+Strength+Changes+Faster+With+Age+Than+BMD+in+Both+Women+and+Men%3A+A+Biomechanical+Study%5BTitle%5D)+AND+%22J+Bone+Miner+Res%22%5BJournal%5D)">Femoral Strength Changes Faster With Age Than BMD in Both Women and Men: A Biomechanical Study.</a> J Bone Miner Res. 30, 2200-2206 (2015).</li>
<li>Zani, L., Erani, P., Grassi, L., Taddei, F., Cristofolini, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Strain+distribution+in+the+proximal+Human+femur+during+in+vitro+simulated+sideways+fall%5BTitle%5D)+AND+%22J+Biomech%22%5BJournal%5D)">Strain distribution in the proximal Human femur during in vitro simulated sideways fall.</a> J Biomech. 48, 2130-2143 (2015).</li>
<li>Dragomir-Daescu, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Robust+QCT%2FFEA+models+of+proximal+femur+stiffness+and+fracture+load+during+a+sideways+fall+on+the+hip%5BTitle%5D)+AND+%22Ann+Biomed+Eng%22%5BJournal%5D)">Robust QCT/FEA models of proximal femur stiffness and fracture load during a sideways fall on the hip.</a> Ann Biomed Eng. 39, 742-755 (2011).</li>
<li>Schileo, E., Balistreri, L., Grassi, L., Cristofolini, L., Taddei, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((To+what+extent+can+linear+finite+element+models+of+human+femora+predict+failure+under+stance+and+fall+loading+configurations%3F%5BTitle%5D)+AND+%22J+Biomech%22%5BJournal%5D)">To what extent can linear finite element models of human femora predict failure under stance and fall loading configurations?</a> J Biomech. 47, 3531-3538 (2014).</li>
<li>Koivumaki, J. E., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Ct-based+finite+element+models+can+be+used+to+estimate+experimentally+measured+failure+loads+in+the+proximal+femur%5BTitle%5D)+AND+%22Bone%22%5BJournal%5D)">Ct-based finite element models can be used to estimate experimentally measured failure loads in the proximal femur.</a> Bone. 50, 824-829 (2012).</li>
<li>Pottecher, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Prediction+of+Hip+Failure+Load%3A+In+Vitro+Study+of+80+Femurs+Using+Three+Imaging+Methods+and+Finite+Element+Models%E2%80%94The+European+Fracture+Study+%28EFFECT%29%5BTitle%5D)+AND+%22Radiology%22%5BJournal%5D)">Prediction of Hip Failure Load: In Vitro Study of 80 Femurs Using Three Imaging Methods and Finite Element Models—The European Fracture Study (EFFECT).</a> Radiology. , 142796(2016).</li>
<li>Rivadeneira, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Femoral+neck+BMD+is+a+strong+predictor+of+hip+fracture+susceptibility+in+elderly+men+and+women+because+it+detects+cortical+bone+instability%3A+the+Rotterdam+Study%5BTitle%5D)+AND+%22J+Bone+Miner+Res%22%5BJournal%5D)">Femoral neck BMD is a strong predictor of hip fracture susceptibility in elderly men and women because it detects cortical bone instability: the Rotterdam Study.</a> J Bone Miner Res. 22, 1781-1790 (2007).</li>
<li>de Bakker, P. M., Manske, S. L., Ebacher, V., Oxland, T. R., Cripton, P. A., Guy, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((During+sideways+falls+proximal+femur+fractures+initiate+in+the+superolateral+cortex%3A+evidence+from+high-speed+video+of+simulated+fractures%5BTitle%5D)+AND+%22J+Biomech%22%5BJournal%5D)">During sideways falls proximal femur fractures initiate in the superolateral cortex: evidence from high-speed video of simulated fractures.</a> J Biomech. 42, 1917-1925 (2009).</li>
<li>Courtney, A. C., Wachtel, E. F., Myers, E. R., Hayes, W. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Age-related+reductions+in+the+strength+of+the+femur+tested+in+a+fall-loading+configuration%5BTitle%5D)+AND+%22J+Bone+Joint+Surg+Am%22%5BJournal%5D)">Age-related reductions in the strength of the femur tested in a fall-loading configuration.</a> J Bone Joint Surg Am. 77, 387-395 (1995).</li>
<li>Cheng, X. G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Assessment+of+the+strength+of+proximal+femur+in+vitro%3A+relationship+to+femoral+bone+mineral+density+and+femoral%5BTitle%5D)+AND+%22Bone%22%5BJournal%5D)">Assessment of the strength of proximal femur in vitro: relationship to femoral bone mineral density and femoral.</a> Bone. 20, 213-218 (1997).</li>
<li>Courtney, A. C., Wachtel, E. F., Myers, E. R., Hayes, W. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Effects+of+loading+rate+on+strength+of+the+proximal+femur%5BTitle%5D)+AND+%22Calcif+Tissue+Int%22%5BJournal%5D)">Effects of loading rate on strength of the proximal femur.</a> Calcif Tissue Int. 55, 53-58 (1994).</li>
<li>Keyak, J., Rossi, S., Jones, K., Les, C., Skinner, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Prediction+of+fracture+location+in+the+proximal+femur+using+finite+element+models%5BTitle%5D)+AND+%22Medical+engineering+%26+physics%22%5BJournal%5D)">Prediction of fracture location in the proximal femur using finite element models.</a> Medical engineering & physics. 23, 657-664 (2001).</li>
<li>Nishiyama, K. K., Gilchrist, S., Guy, P., Cripton, P., Boyd, S. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Proximal+femur+bone+strength+estimated+by+a+computationally+fast+finite+element+analysis+in+a+sideways+fall+configuration%5BTitle%5D)+AND+%22J+Biomech%22%5BJournal%5D)">Proximal femur bone strength estimated by a computationally fast finite element analysis in a sideways fall configuration.</a> J Biomech. 46, 1231-1236 (2013).</li>
<li>Langton, C. M., Njeh, C. F. <a target="_blank" href="http://scholar.google.com/scholar?hl=en&safe=off&q=author%3aLangton%2C+CM+%22The+physical+measurement+of+bone%22">The physical measurement of bone</a>. , CRC Press. (2016).</li>
<li>Ariza, O., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Comparison+of+explicit+finite+element+and+mechanical+simulation+of+the+proximal+femur+during+dynamic+drop-tower+testing%5BTitle%5D)+AND+%22J+Biomech%22%5BJournal%5D)">Comparison of explicit finite element and mechanical simulation of the proximal femur during dynamic drop-tower testing.</a> J Biomech. 48, 224-232 (2015).</li>
</ol>

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我们提出了一项议定书，断裂测试尸体股骨近端在秋天的髋关节的配置，我们已经成功地测试了大约 200 个样本。议定书 》 包括几个内部设计的夹具为股骨强度在不同加载条件下的试验。夹具允许测试在不同的测试速度和骨方向的左边和右边股骨。后安装夹具和测量仪器，测试的玻璃纤维股骨骨折以确保所有的硬件和软件工具正确连接，同步，工作和正确地记录的信号和视频。只是之前实际尸体...

股骨骨折风险评估的新方法及落在髋关节骨折预防发展需要对断裂过程中所涉及的生物力学过程的全面理解。尸体股骨近端强度测试已被证明是有效地确定股骨强度与股骨提供重要的见解，在此过程1，2结构承载能力影响因素之间的关系,3.实验测量股骨强度也可用于验证的基于定量计算层析成像的有限元分析 (QCT/FEA) 使断裂强度4，5，一个非侵入性的估计 6，7。
到目前为止，并无接受的标准程序来测试整个股骨标本骨折。要隔离临床可以衡量变量 （例如骨密度和几何） 和他们对股骨强度的影响，是实验测试必须以可控和可重复的方式进行。尸体股骨有不规则的形状和范围大小8中，可以索取使它无法使用内置固定装置的标准试验机测试不同年龄段的男性或女性尸体。在横盘落在髋关节事件，股骨大转子经历时股骨近端可能会遇到复杂的载荷，包括压缩、 张力、 弯矩和扭矩，压缩加载。测试这种加载场景添加实验设计的复杂性。因此，夹具，作为一个重要组成部分的测试协议，必须专门设计、 捏造，并安装以容纳股样本的不同形状和大小的不同的测试速度。此夹具也必须持有标本测试所需的方向来模拟放在臀部上坠落可能冲击载荷范围内。要满足各种各样的条件，需要有多个固定夹具和运动部件连接尽量发挥在系统中，获得平滑的荷载-位移响应的方式。
在测试过程中，可靠的数据采集也是关键的。实验设计必须纳入必要的负载细胞、 位移传感器、 信号放大器和改良剂对准确地测量力和力矩根本支持。此外，高速视频获得同步采集的部队与股骨的前部和后部意见是必要的有助于了解导致骨折，鉴定骨折类型，事件的顺序和精确定义股骨强度4，9。
虽然有宝贵的实验研究在文献中对整个股骨测试，已发布的协议要么缺乏细节上如何进行了测试，要么是非常不同的从一项研究的另一个，真正使他们重现10， 11。当前工作的目标是介绍机械测试可以作为努力的起点用于标准化测试的可重复性和可再现的骨组织的股骨样品的协议。为此，我们设计和制作测试夹具，用于测试约 200 尸体股骨。测试夹具包括底部夹具和十字头夹具。底部夹具 （图 1A-E） 举行股骨在测试过程中所需的方向，包括转子负荷细胞和连接到股骨干 6 信道负载细胞。它还可容纳三个独立的翻译，以便定位的骨骨折测试。旋转点添加到模仿膝关节。底部夹具的主要部分被组成的厚片的不锈钢和铝，使非常僵硬的夹具。负载细胞被附加到底部夹具在测试过程中测量股骨大转子上的压缩力。十字头夹具 (图 2A-2E) 包括两个铝基座和两个非常僵硬幻灯片球轴承 （连接在一起的铝板），在测试过程中占股骨头的运动，容纳为左、 右股骨。负载单元格包括在十字头夹具措施压缩力。附加到负载单元格铝杯用于将压缩荷载传递到股骨头。我们的方法用于男女各种尺寸与左、 右股骨、 颈干角，骨密度，和加载条件模仿侧身落在臀部。在我们的实验测试速度为 5、 100 和 700 毫米/秒，但他们可以设置为任何值的测试计算机上可用。设计工装夹具有两个主要组件，一个连接到测试机十字头和其他连接到测试框架。两个部分被即刻负载细胞足以测量力和力矩边界条件在所有支持。此外，两个高速摄像机被用来在测试过程中记录断裂事件。骨折后，一套 x 射线和计算层析成像 (CT) 扫描后实验性骨折分析得到了。结果从这些实验包括断裂强度和能源目前用于额外的诊断工具的研究，最终改善骨质疏松症患者近端断裂强度的评估。

<table><tbody><tr><td>CT scanner</td><td>Siemens</td><td>Somatom Definition scanner (Siemens, Malvern, PA)</td><td>CT scanning equipment</td></tr><tr><td>Quantitative CT Phantom</td><td>Midways Inc, San Francisco, CA</td><td>Model 3 CT calibration Phantom</td><td>Used for obtaining BMD values from Hounsfield units in the CT image</td></tr><tr><td>Hygenic Orthodontic Resin (PMMA)</td><td>Patterson Dental Supply</td><td>H02252</td><td>Controlled substance and can be purchased with proper approval</td></tr><tr><td>Freezer</td><td>Kenmore</td><td>N/A</td><td>This is a -20&lt;sup&gt;o&lt;/sup&gt;C storage for bones</td></tr><tr><td>X-ray scanner</td><td>General Electric</td><td>46-270615P1</td><td>X-ray imaging equipment.</td></tr><tr><td>X-ray films</td><td>Kodak</td><td>N/A</td><td>Used to display x-ray images</td></tr><tr><td>X-ray developer</td><td>Kodak X-Omatic</td><td>M35A X-OMAT</td><td>Used for developing X-ray images</td></tr><tr><td>X-ray Cassette</td><td>Kodak X-Omatic</td><td>N/A</td><td>Used for holding x-ray films</td></tr><tr><td>Physiologic Saline (0.9% Sodium Chloride)</td><td>Baxter</td><td>NDC 0338-0048-04</td><td>Used for keeping samples hydrated</td></tr><tr><td>Scalpels and scrapers</td><td>Bard-Parker</td><td>N/A</td><td>Used to clean the bone from soft tissue</td></tr><tr><td>Fume Hood</td><td>Hamilton</td><td>70532</td><td>Used for ventilation when preparing PMMA for potting of specimens</td></tr><tr><td>Single axis load cell</td><td>Transducer Techniques, Temecula, CA, USA</td><td>LPU-3K; S/N 219627</td><td>Capacity 3000 LBS</td></tr><tr><td>Six channel load cell</td><td>JR3,Woodland, CA</td><td>45E15A4</td><td>Mechanical load rating 1000N</td></tr><tr><td>Linear potentiometer</td><td>Novotechnik, Southborough, MA, USA</td><td></td><td>Used to acquire linear displacements during testing</td></tr><tr><td>Slide ball bearing</td><td>Schneeberger</td><td>Type NK</td><td>Part of the testing fixture</td></tr><tr><td>Mechanical testing machine</td><td>MTS, Minneapolis, MN</td><td>858 Mini Bionix II</td><td>Used for compression of femur</td></tr><tr><td>Lighting unit</td><td>ARRI</td><td></td><td>Needed for high speed video recordings</td></tr><tr><td>high-speed video camera</td><td>Photron Inc., San Diego, CA, USA</td><td>Photron Fastcam APX-RS</td><td>Used to capture the high speed video recordings of the fracture events</td></tr><tr><td>Photron FASTCAM Viewer</td><td>Photron Inc., San Diego, CA, USA</td><td>Ver.3392(x64)</td><td>Used to view the high speed video recordings</td></tr><tr><td>Camera lens</td><td>Zeiss</td><td>Zeiss Planar L4/50 ZF Lens</td><td>Needed to high image resolution</td></tr><tr><td>Signal conditioner board (DAQ)</td><td>National Instruments</td><td></td><td>Input/output signal connector</td></tr><tr><td>Signal Express</td><td>National Instruments</td><td>N/A</td><td>Data acquisition software</td></tr><tr><td>Laptop Computer</td><td>Dell</td><td>N/A</td><td>Used to monitor and acquire all signals from the testing procedure</td></tr></tbody></table>

method and instrumented fixture for femoral fracture testing in a sideways fall-on-the-hip position

机械测试的股骨带来有价值的见解，了解临床可以衡量的变量，例如骨矿物密度分布和几何形状对股骨力学性能的贡献。目前，尚没有用于这种措施强度和刚度的几何复杂骨头的机械试验标准协议。为了缩小这种差距我们制订了一项议定书，尸体股骨骨折并衡量其生物力学参数测试。此协议说明一套适应性强的夹具，以容纳不同的负载大小和方向为可能的骨方向在秋天会计髋关节配置，测试速度、 骨大小和左的腿右腿变化。股骨准备测试由清洗、 切割、 扫描和灌封的远端和股骨大转子接触表面在 poly(methyl methacrylate))，提出在不同的协议。准备好的标本被放置在测试夹具中模仿侧身落在臀部的位置和加载断裂。在测试期间，两个负载细胞测量垂直力适用于股骨头和股骨大转子、 六轴负载细胞测量的部队，并时刻在股骨远端和位移传感器测量差动位移之间股骨头和股骨转子区联系支持。高速摄像机被用来同步记录在测试过程中的断裂事件发生的顺序。这种数据减少允许我们进行归类的强度、 刚度，和断裂能的近 200 骨质疏松，骨质疏松，和正常的尸体股骨，为进一步发展基于工程的骨质疏松症的诊断工具的研究。

内部的夹具安装后标夹具从试验机中删除。第一，底部重夹具是安装和固定 (图 1)。这包括扩展的手臂想站 6 通道负载细胞，这也使股骨在预期内收角对齐。下一步，包括两个无摩擦滑动轴承十字头夹具安装以适应应用程序的负载和股骨头部的动作期间骨折 (图 2)。上部的夹具是可调的测试左和右腿。一旦所有夹具都安装，安装...

Watch this Scientific Journal Video about Method and Instrumented Fixture for Femoral Fracture Testing in a Sideways Fall-on-the-Hip Position at JoVE.com

Method and Instrumented Fixture for Femoral Fracture Testing in a Sideways Fall-on-the-Hip Position

在这份手稿，我们提出一项议定书，在髋关节的配置使用标准伺服液压架上安装检测的夹具侧身摔倒骨折试验尸近端股骨。在测试过程中采集包括部队、 时刻和位移以及两个高速视频流的九个数字化的信号。

方法和股骨骨折测试在横盘整理的秋天在臀部位置检测的夹具

Mechanical testing of femora brings valuable insights into understanding the contribution of clinically-measureable variables such as bone mineral density ...

method-instrumented-fixture-for-femoral-fracture-testing-sideways

Research

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JoVE Core

JoVE Journal

Mechanical Engineering

Bioengineering

Unit 1

Force System Resultants

SCIENTISTS IN ACTION

10.0K 次观看.  Mayo Clinic. 在这份手稿，我们提出一项议定书，在髋关节的配置使用标准伺服液压架上安装检测的夹具侧身摔倒骨折试验尸近端股骨。在测试过程中采集包括部队、 时刻和位移以及两个高速视频流的九个数字化的信号。

视频: Method and Instrumented Fixture for Femoral Fracture Testing in a Sideways Fall-on-the-Hip Position

Creating Rigidly Stabilized Fractures for Assessing Intramembranous Ossification, Distraction Osteogenesis, or Healing of Critical Sized Defects

Assessing modes of skeletal repair is essential for developing therapies to be used clinically to treat fractures. Mechanical stability plays a large role in healing of bone injuries. In the worst-case scenario mechanical instability can lead to delayed or non-union in humans. However, motion can also stimulate the healing process. In fractures that have motion cartilage forms to stabilize the fracture bone ends, and this cartilage is gradually replaced by bone through recapitulation of the developmental process of endochondral ossification. In contrast, if a bone fracture is rigidly stabilized bone forms directly via intramembranous ossification. Clinically, both endochondral and intramembranous ossification occur simultaneously. To effectively replicate this process investigators insert a pin into the medullary canal of the fractured bone as described by Bonnarens4. This experimental method provides excellent lateral stability while allowing rotational instability to persist. However, our understanding of the mechanisms that regulate these two distinct processes can also be enhanced by experimentally isolating each of these processes. We have developed a stabilization protocol that provides rotational and lateral stabilization. In this model, intramembranous ossification is the only mode of healing that is observed, and healing parameters can be compared among different strains of genetically modified mice 5-7, after application of bioactive molecules 8,9, after altering physiological parameters of healing 10, after modifying the amount or time of stabilization 11, after distraction osteogenesis 12, after creation of a non-union 13, or after creation of a critical sized defect. Here, we illustrate how to apply the modified Ilizarov fixators for studying tibial fracture healing and distraction osteogenesis in mice.

This article describes a method for stabilizing long bone fractures that is based on the application of modified Ilizarov external fixators 1-3. After application of the fixators and creation of the bone injury, healing can be assessed, distraction osteogenesis can be performed, or non-union or critical sized defect can be created and used to study therapeutic interventions.

建立评估膜内骨化硬性稳定骨折，牵张成骨，或临界中小企业缺损愈合

Assessing modes of skeletal repair is essential for developing therapies to be used clinically to treat fractures. Mechanical stability plays a large role ...

科研

医学

An Improved Mechanical Testing Method to Assess Bone-implant Anchorage

Recent advances in material science have led to a substantial increase in the topographical complexity of implant surfaces, both on a micro- and a nano-scale. As such, traditional methods of describing implant surfaces -&#160;namely numerical determinants of surface roughness -&#160;are inadequate for predicting in vivo performance. Biomechanical testing provides an accurate and comparative platform to analyze the performance of biomaterial surfaces. An improved mechanical testing method to test the anchorage of bone to candidate implant surfaces is presented. The method is applicable to both early and later stages of healing and can be employed for any range of chemically or mechanically modified surfaces -&#160;but not smooth surfaces. Custom rectangular implants are placed bilaterally in the distal femora of male Wistar rats and collected with the surrounding bone. Test specimens are prepared and potted using a novel breakaway mold and the disruption test is conducted using a mechanical testing machine. This method allows for alignment of the disruption force exactly perpendicular, or parallel, to the plane of the implant surface, and provides an accurate and reproducible means for isolating an exact peri-implant region for testing.

An improved method to mechanically test bone anchorage to candidate implant surfaces is presented. This method allows for alignment of the disruption force exactly perpendicular, or parallel, to the plane of the implant surface, and provides an accurate means to direct the disruption forces to an exact peri-implant region.

一种改进的机械性能测试方法来评估骨种植体支抗

Recent advances in material science have led to a substantial increase in the topographical complexity of implant surfaces, both on a micro- and a ...

生物工程

A Mini-Invasive Internal Fixation Technique for Studying Immobilization-Induced Knee Flexion Contracture in Rats

Joint contracture, resulting from a prolonged joint immobilization, is a common complication in orthopedics. Currently, utilizing an internal fixation to restrict knee joint mobility is a widely accepted model to generate experimental contracture. However, implanting application will inevitably cause surgical trauma to the animals. Aiming to develop a less invasive approach, we combined a muscle-gap separation modus with a previously reported mini-incision skill during the surgical procedure: Two mini skin incisions were made on the lateral thigh and leg, followed by performing muscle-gap separation to expose the bone surface. The rat knee joint was gradually immobilized by a preconstructed internal fixation at approximately 135&#176; knee flexion without interfering essential nerves or blood vessels. As expected, this simple technique permits rapid postoperative rehabilitation in animals. The correct position of the internal fixation was confirmed by an x-ray or micro-CT scanning analysis. The range of motion was significantly restricted in the immobilized knee joint than that observed in the contralateral knee joint demonstrating the effectiveness of this model. Besides, histological analysis revealed the development of fibrous deposition and adhesion in the posterior-superior knee joint capsule over time. Thus, this mini-invasive model may be suitable for mimicking the development of immobilized knee joint contracture.

Here, we present a protocol to describe a minimally invasive technique for knee joint immobilization in a rat model. This reproducible protocol, basing on muscle-gap separation modus and the mini-incision skill, is suitable for studying the underlying molecular mechanism of acquired joint contracture.

研究大鼠固定性诱导膝关节弯曲收缩的微型侵入性内固定技术

Joint contracture, resulting from a prolonged joint immobilization, is a common complication in orthopedics. Currently, utilizing an internal fixation to ...

发育生物学

Adjustable Stiffness, External Fixator for the Rat Femur Osteotomy and Segmental Bone Defect Models

The mechanical environment around the healing of broken bone is very important as it determines the way the fracture will heal. Over the past decade there has been great clinical interest in improving bone healing by altering the mechanical environment through the fixation stability around the lesion. One constraint of preclinical animal research in this area is the lack of experimental control over the local mechanical environment within a large segmental defect as well as osteotomies as they heal. In this paper we report on the design and use of an external fixator to study the healing of large segmental bone defects or osteotomies. This device not only allows for controlled axial stiffness on the bone lesion as it heals, but it also enables the change of stiffness during the healing process in vivo. The conducted experiments have shown that the fixators were able to maintain a 5 mm femoral defect gap in rats in vivo during unrestricted cage activity for at least 8 weeks. Likewise, we observed no distortion or infections, including pin infections during the entire healing period. These results demonstrate that our newly developed external fixator was able to achieve reproducible and standardized stabilization, and the alteration of the mechanical environment of in vivo rat large bone defects and various size osteotomies. This confirms that the external fixation device is well suited for preclinical research investigations using a rat model in the field of bone regeneration and repair.

One constraint of preclinical research in the field of bone repair is the lack of experimental control over the local mechanical environment within a healing bone lesion. We report the design and use of an external fixator for bone repair with the ability to change fixator stiffness in vivo.

可调节刚度，外固定支架的大鼠股骨截骨和节段性骨缺损模型

The mechanical environment around the healing of broken bone is very important as it determines the way the fracture will heal. Over the past decade there ...

A Method to Estimate Cadaveric Femur Cortical Strains During Fracture Testing Using Digital Image Correlation

This protocol describes the method using digital image correlation to estimate cortical strain from high speed video images of the cadaveric femoral surface obtained from mechanical testing. This optical method requires a texture of many contrasting fiduciary marks on a solid white background for accurate tracking of surface deformation as loading is applied to the specimen. Immediately prior to testing, the surface of interest in the camera view is painted with a water-based white primer and allowed to dry for several minutes. Then, a black paint is speckled carefully over the white background with special consideration for the even size and shape of the droplets. Illumination is carefully designed and set such that there is optimal contrast of these marks while minimizing reflections through the use of filters. Images were obtained through high speed video capture at up to 12,000 frames/s. The key images prior to and including the fracture event are extracted and deformations are estimated between successive frames in carefully sized interrogation windows over a specified region of interest. These deformations are then used to compute surface strain temporally during the fracture test. The strain data is very useful for identifying fracture initiation within the femur, and for eventual validation of proximal femur fracture strength models derived from Quantitative Computed Tomography-based Finite Element Analysis (QCT/FEA).

In this protocol, the femur surface strains are estimated during fracture testing using the digital image correlation technique. The novelty of the method involves application of a high-contrast stochastic speckle pattern on the femur surface, carefully specified illumination, high speed video capture, and digital image correlation analysis for strain calculations.

基于数字图像相关的骨折检测中股骨皮质应变的估算方法

This protocol describes the method using digital image correlation to estimate cortical strain from high speed video images of the cadaveric femoral ...

Imaging of the Microstructural Failure Mechanism in the Human Hip

Imaging the bone microstructure under progressively increasing loads allows for observing the microstructural failure behavior of bone. Here, we describe a protocol for obtaining a sequence of three-dimensional microstructural images of the entire proximal femur under progressively increasing deformation, causing clinically relevant fractures of the femoral neck. The protocol is demonstrated using four femora from female donors aged 66-80 years at the lower end of bone mineral density in the population (T-score range = &#8722;2.09 to &#8722;4.75). A radio-transparent compressive stage was designed for loading the specimens replicating a one-leg stance, while recording the applied load during&#160;micro-computed tomography (micro-CT) imaging. The field of view was 146 mm wide and 132 mm high, and the isotropic pixel size was 0.03 mm. The force increment was based on finite-element predictions of the fracture load. The compressive stage was used to apply the displacement to the specimen and enact the prescribed force increments. Sub-capital fractures due to opening and shear of the femoral neck occurred after four to five load increments. The micro-CT&#160;images and the reaction force measurements were processed to study the bone strain and energy absorption capacity. Instability of the cortex appeared at the early loading steps. The subchondral bone in the femoral head displayed large deformations reaching 16% before&#160;fracture, and a progressive increase in the support capacity up to&#160;fracture. The deformation energy linearly increased with the displacement up to&#160;fracture, while the stiffness decreased to near-zero values immediately before&#160;fracture. Three-fourths of the fracture energy was taken by the specimen during the final 25% force increment. In conclusion, the protocol developed revealed a remarkable energy absorption capacity, or damage tolerance, and a synergic interaction between the cortical and trabecular bone at an advanced donor age.

The protocol enables the measurement of the deformation of the bone microstructure in the entire proximal human femur and its toughness by combining large-volume micro-CT scanning, a custom-made compressive stage, and advanced image processing tools.

人髋关节微观结构失效机制的成像

Imaging the bone microstructure under progressively increasing loads allows for observing the microstructural failure behavior of bone. Here, we describe ...

工程学

A Reliable and Reproducible Critical-Sized Segmental Femoral Defect Model in Rats Stabilized with a Custom External Fixator

Orthopedic research relies heavily on animal models to study mechanisms of bone healing in vivo as well as investigate the new treatment techniques. Critical-sized segmental defects are challenging to treat clinically, and research efforts could benefit from a reliable, ambulatory small animal model of a segmental femoral defect. In this study, we present an optimized surgical protocol for the consistent and reproducible creation of a 5 mm critical diaphyseal defect in a rat femur stabilized with an external fixator. The diaphyseal ostectomy was performed using a custom jig to place 4 Kirschner wires bicortically, which were stabilized with an adapted external fixator device. An oscillating bone saw was used to create the defect. Either a collagen sponge alone or a collagen sponge soaked in rhBMP-2 was implanted into the defect, and the bone healing was monitored over 12 weeks using radiographs. After 12 weeks, rats were sacrificed, and histological analysis was performed on the excised control and treated femurs. Bone defects containing only collagen sponge resulted in non-union, while rhBMP-2 treatment yielded the formation of a periosteal callous and new bone remodeling. Animals recovered well after implantation, and external fixation proved successful in stabilizing the femoral defects over 12 weeks. This streamlined surgical model could be readily applied to study bone healing and test new orthopedic biomaterials and regenerative therapies in vivo.

In vivo mammalian models of critical-sized bone defects are essential for researchers studying healing mechanisms and orthopedic therapies. Here, we introduce a protocol for the creation of reproducible, segmental, femoral defects in rats stabilized using external fixation.

一种可靠、可重复的可重复的大鼠部分股骨缺陷模型

Orthopedic research relies heavily on animal models to study mechanisms of bone healing in vivo as well as investigate the new treatment techniques. ...

Proximal Cadaveric Femur Preparation for Fracture Strength Testing and Quantitative CT-based Finite Element Analysis

Cadaveric fracture testing is routinely used to understand factors that affect proximal femur strength. Because ex vivo biological tissues are prone to lose their mechanical properties over time, specimen preparation for experimental testing must be performed carefully to obtain reliable results that represent in vivo conditions. For that reason, we designed a protocol and a set of fixtures to prepare the femoral specimens such that their mechanical properties experienced minimal changes. The femora were kept in a frozen state except during preparation steps and mechanical testing. The relevant clinical measures of total hip and femoral neck bone mineral density (BMD) were obtained with a clinical dual X-ray absorptiometry (DXA) bone densitometer, and the 3D geometry and distribution of bone mineral were obtained using CT with a calibration phantom for quantitative estimations based on the greyscale values. Any possible bone disease, fracture, or the presence of implants or artifacts affecting the bone structure, was ruled out with X-ray scans. For preparation, all bones were carefully cleaned of excess soft tissue, and were cut and potted at the internal rotation angle of interest. A cutting fixture allowed the distal end of the bone to be cut off leaving the proximal femur at a desired length. To allow positioning of the femoral neck at prescribed angles during later CT scanning and mechanical testing, the proximal femoral shafts were potted in polymethylmethacrylate (PMMA) using a fixture designed specifically for desired orientations. The data collected from our experiments were then used for validation of quantitative computed tomography (QCT)-based finite element analysis (FEA), as described in a different protocol. In this manuscript, we present the protocol for the precise bone preparation for mechanical testing and subsequent QCT/FEA modeling. The current protocol was successfully applied to prepare about 200 cadaveric femora over a 6-year time period.

We present a robust protocol on how to carefully preserve and prepare cadaveric femora for fracture testing and quantitative computed tomography imaging. The method provides precise control over input conditions for the purpose of determining relationships between bone mineral density, fracture strength, and defining finite element model geometry and properties.

近端股骨尸制备基于CT的断裂强度测试和定量的有限元分析

Cadaveric fracture testing is routinely used to understand factors that affect proximal femur strength.  Because ex vivo biological tissues are prone to ...

Cantilever Bending of Murine Femoral Necks

Fractures in the femoral neck are a common occurrence in individuals with osteoporosis. Many mouse models have been developed to assess disease states and therapies, with biomechanical testing as a primary outcome measure. However, traditional biomechanical testing focuses on torsion or bending tests applied to the midshaft of the long bones. This is not typically the site of high-risk fractures in osteoporotic individuals. Therefore, a biomechanical testing protocol was developed that tests the femoral necks of murine femurs in cantilever bending loading to replicate better the types of fractures experienced by osteoporosis patients. Since the biomechanical outcomes are highly dependent on the flexural loading direction relative to the femoral neck, 3D printed guides were created to maintain a femoral shaft at an angle of 20&#176; relative to the loading direction. The new protocol streamlined the testing by reducing variability in alignment (21.6&#176; &plusmn; 1.5&#176;, COV = 7.1%, n = 20) and improved reproducibility in the measured biomechanical outcomes (average COV = 26.7%). The new approach using the 3D printed guides for reliable specimen alignment improves rigor and reproducibility by reducing the measurement errors due to specimen misalignment, which should minimize sample sizes in mouse studies of osteoporosis.

The present protocol describes the development of a reproducible testing platform for murine femoral necks in a cantilever bending set-up. Custom 3D printed guides were used to consistently and rigidly fix the femurs in optimal alignment.

鼠股颈悬臂弯曲

Fractures in the femoral neck are a common occurrence in individuals with osteoporosis. Many mouse models have been developed to assess disease states and ...

The Generation of Closed Femoral Fractures in Mice: A Model to Study Bone Healing

Bone fractures impose a tremendous socio-economic burden on patients, in addition to significantly affecting their quality of life. Therapeutic strategies that promote efficient bone healing are non-existent and in high demand. Effective and reproducible animal models of fractures healing are needed to understand the complex biological processes associated with bone regeneration. Many animal models of fracture healing have been generated over the years; however, murine fracture models have recently emerged as powerful tools to study bone healing. A variety of open and closed models have been developed, but the closed femoral fracture model stands out as a simple method for generating rapid and reproducible results in a physiologically relevant manner. The goal of this surgical protocol is to generate unilateral closed femoral fractures in mice and facilitate a post-fracture stabilization of the femur by inserting an intramedullary steel rod. Although devices such as a nail or a screw offer greater axial and rotational stability, the use of an intramedullary rod provides a sufficient stabilization for consistent healing outcomes without producing new defects in the bone tissue or damaging nearby soft tissue. Radiographic imaging is used to monitor the progression of callus formation, bony union, and subsequent remodeling of the bony callus. Bone healing outcomes are typically associated with the strength of the healed bone and measured with torsional testing. Still, understanding the early cellular and molecular events associated with fracture repair is critical in the study of bone tissue regeneration. The closed femoral fracture model in mice with intramedullary fixation serves as an attractive platform to study bone fracture healing and evaluate therapeutic strategies to accelerate healing.

The murine closed femoral fracture model is a powerful platform to study fracture healing and novel therapeutic strategies to accelerate bone regeneration. The goal of this surgical protocol is to generate unilateral closed femoral fractures in mice using an intramedullary steel rod to stabilize the femur.

小鼠闭合性股骨骨折的形成: 骨愈合模型的研究

Bone fractures impose a tremendous socio-economic burden on patients, in addition to significantly affecting their quality of life. Therapeutic strategies ...