我们要感谢的材料和结构试验核心设施梅奥诊所寻求技术支持。此外，我们要感谢遵义伯格伦德，布兰特纽曼，乔恩运书房Buijs，博士，在研究过程中他们的帮助。这项研究是由财政从格兰杰基金会格兰杰创新基金的支持。

注:本协议提出的所有研究是由梅奥诊所的机构审查委员会（IRB）的批准。尸骨了来自不同组织的一个为期6年获得。所有标本72小时死亡的内收集的，包裹在盐水饱和毛巾，并储存于-20℃，直至准备。 1.使用DXA测量骨密度<ol><li>除去保持在-20℃下冷冻样品在室温下解冻约24小时标本并不需要从原始包装中删除，如果最软组织已被删除。 </li><li>大米使用两个5磅袋占了软组织。封面上DXA表两种大米袋用塑料袋，以防止污染。的米袋将模拟周边扫描期间的软组织（体内 ）， 如图1。 </li><li>保护DXA扫描器表面衬塑纸，并放置2个塑料包装里CE袋放在扫描仪表（ 图1A）。 </li><li>莱在的大米包装袋顶部2股骨（左，右），使得近端（包括股骨头）集中在包包和后侧下跌（ 图1B）。这模仿患者仰卧在他们的后面。 </li><li>覆盖前/暴露股骨近端年底与另外两个5磅的大米包装袋（ 图1C）。 </li><li>机头跟在股骨近端，并根据病人的骨密度测量（ 图1C）的标准机构的程序扫描股骨。按照具体DXA制造商的说明。 <ol><li>从DXA机软件界面执行正常股骨扫描。选择股骨考试，通过相应地按压向左或向右箭头上DXA手臂上的尸体股骨顶部的DXA手臂的位置，并通过点击"开始"按钮，开始考试。通过点击"分析"执行BMD分析。 不E:从扫描得到的自动T分数分类骨为正常，骨质减少或骨质疏松性（ 图1D）。按照具体DXA制造商的说明。 </li></ol></li></ol> 2.清洗，切割和钻孔骨的骨远端<ol><li>通过仔细地除去从骨的任何剩余的软组织清洁股骨的最基端为300 mm。此步骤是必须允许PMMA期间在机械测试准备制陶过程联系骨头。骨头不需要解冻到室温这个过程。 </li><li>消毒用70％异丙醇的工作区，并覆盖在一侧（ 图2A）与塑料薄膜吸收纸垫的表。设置在桌子上（ 图2B）的开始清洗，切割（ 图2A至2H）的整个过程全股骨。穿戴个人防护装备（PPE），包括手套和保护眼睛。 </li><li>刮去多余的骨膜和用刮刀和手术刀（ 图2C，2H）切去多余的组织。 </li><li>放置骨中的定制切割夹具如图2D与抗夹具的丙烯酸板股骨的头部。 </li><li>对准并靠住上切割夹具（ 图2D）的两个插针的骨干。 </li><li>固定骨头拧紧向下骨干开槽板的夹具;如果骨不平躺在夹具上，挂前端关闭桌面并且还根据需要握住标本就位（ 图2D）任选拉链扎股骨颈。 </li><li>切割通过开槽板作为引导用铸件切割器（ 图2E）的股骨的远端轴;持有用干抹布/毛巾骨头更好的抓地力。 </li><li>除去从夹具的骨;后切正常骨长度为255毫米（ 图2F）。 </li><li>用刮匙约25毫米深清洁骨髓的骨髓腔。然后，将纱布海绵吸干的内表面。取出纱布刚刚之前放置在模具中的股骨的远端。把手用干毛巾/抹布骨和钻10毫米的孔，通过所述远端在从试样的近端切割端约25毫米。注:这是使PMMA穿透运河和牢固地固定骨头。 </li></ol> 3.灌封骨<ol><li>设计和制造封装容器。灌封容器形成5毫米厚的丙烯酸系片材，并具有以下外部尺寸50毫米乘50毫米的方形横截面和100毫米高（ 图3A）。 </li><li>适当的骨骼识别标签封装容器（ 图3A和3B -看到亚克力盒标签）。 </li><li>调整嵌入夹具适当取向（左腿或右腿; 例如 15°或30°内旋转）。 </li><li>放置灌封容器在灌封容器（ 图3B）中嵌入夹具，代替骨的基部和与指针在夹具（ 图3C）对齐颈部到骨的内部的旋转角度调整到所需的值。 </li><li>测量60克PMMA粉，并在通风橱用30克液体树脂混合，直到粉末溶解。该混合物应该是可流动的。使用一次性纸杯这一进程。 </li><li>将混合物倒入带有通风橱（ 图3D）下骨灌封容器，允许以固化约10 - 15分钟，直到PMMA是透明和硬的。这应该只填写〜PMMA的灌封容器的1/2。小心包装在盐水饱和毛巾骨，以防止由于聚甲基丙烯酸甲酯聚合（ 图3E）中的发热组织干。 </li><li>定期检查股骨，以确保它保持在对齐在固化过程中的容器。 </li><li>从灌封夹具除去股骨并用盐水浸泡纸巾（ 图3E）包裹。 </li><li>在通风橱下制备90克PMMA的如在步骤3.5解释和完全填充灌封容器。治愈PMMA约10 - 15分钟，直到它变得坚硬。 </li><li>树脂固化后，紧紧包裹在盐水浸湿的纸巾/重新包骨，在冷冻室-20℃的塑料袋和存储样本覆盖。 </li></ol> 4.成像的X射线骨 （ 注意！使用机器时，与X射线辐射的适当的照顾工作） <ol><li>如果使用用于X射线的薄膜，由旋钮顺时针旋转（在显影剂室）打开X射线显影剂上至少20分钟（按照制造商说明书）扫描前。 </li><li>确保有之前的X射线照相暗盒未曝光的胶片;卡带只能在一个黑暗的房间打开。 </li><li>打开机器上解锁并延长机器头上。 </li><li>放置一个购物的光束的路径下和放置一个盒上的光束（ 图4A）下的车。 </li><li>地点和录像带上（ 图4B）股骨定位;两个方向将被捕获:内侧 - 外侧视图和前 - 后视图。相应地标出标本的图像。 </li><li>第一次曝光后，交换铅和骨骼的位置。 </li><li>覆盖已露出的一半与铅和在未曝光侧的第二取向露出骨。这允许用户使用一个X射线胶片用于在两个取向（ 图4C-D）的一个单一的骨。 </li><li>更换磁带，每个股骨旋转到第二方位。 </li><li>在一个单一的股骨的情况下，覆盖引线盖的磁带盒的一半，以避免整个膜的X射线的初始曝光。 </li><li>移动个人防护铅衬便携式墙后面，使用触发器揭露骨头。 </li><li>完成后，返回X射线头锁定和存储位置，转动钥匙到X射线机上关闭并删除曝光X光片。 </li><li>开发该膜，得到使用普通膜显影剂的X射线图像（ 图4E）。打开白色的光在房间里，找到了电影的开发。打开红灯打开磁带之前关闭的白色光，并与电影发展过程中进行。打开纸盒，并通过开发商放电影。打开白色光，并且一旦膜已经开发关掉红光。 </li></ol> 5.骨骼CT扫描<ol><li>从冰箱扫描约24小时前，剔除骨头。骨骼必须在扫描之前完全解冻。 </li><li>确保骨头被包裹在塑料袋进行扫描，以尽量减少清理底。 </li><li>放置并固定股骨和在CT扫描灯具（ 图5A-B）的校准幻像。在Fixture保持校准体模（ 图5C），也保持在一个方向（ 图5D-E）的具有期望用于随后机械测试的取向相同的股骨。这种交叉登记需要在QCT / FEA建模过程（在不同的协议描述）使用从CT扫描（ 图5F）中的数据。 注:夹具被设计为使得它暴露作CT扫描股骨而不妨碍股骨近端（股骨头，颈，大转子，和近侧部轴）。 </li><li>确保与在CT扫描器股骨沿固定装置使用系统激光作为导向件（ 图5D-E）的正确对准。重新检查与CT造影长轴激光夹具的取向（按激光的开/关按钮）。假想不需要，因为它被固定在夹具要与激光对准。按零按钮操零从机器的控制面板的表中的位置N（→0←）在控制面板上。 </li><li>继CT标准作业程序，在120 kVp的，216毫安秒，1秒旋转时间，操作CT机，并使用超高分辨率模式（晌礼）的1间距。这给出了0.4毫米的切片厚度，以及0.30的像素大小 - 取决于视场（FOV）字段的为0.45毫米。 </li><li>前机械测试检查的CT扫描数据，以确保感兴趣的图像被捕获并保存。重新冻结在-20℃的骨，直到实验当天。 </li></ol>

<ol>
	<li>Cristofolini, L., Schileo, E., Juszczyk, M., Taddei, F., Martelli, S., Viceconti, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mechanical+testing+of+bones:+the+positive+synergy+of+finite-element+models+and+in+vitro+experiments.">Mechanical testing of bones: the positive synergy of finite-element models and in vitro experiments.</a> Philos Trans A Math Phys Eng Sci. 368, 2725-2763 (2010).</li><li>Cartner, J. L., Hartsell, Z. M., Ricci, W. M., Tornetta, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Can+we+trust+ex+vivo+mechanical+testing+of+fresh-frozen+cadaveric+specimens?+The+effect+of+postfreezing+delays.">Can we trust ex vivo mechanical testing of fresh-frozen cadaveric specimens? The effect of postfreezing delays.</a> J Orthop Trauma. 25 (8), 459-461 (2011).</li><li>An, Y. H., Draughn, R. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Mechanical testing of bone and the bone-implant interface. , (1999).</li><li>van Haaren, E. H., van der Zwaard, B. C., van der Veen, A. J., Heyligers, I. C., Wuisman, P. I., Smit, T. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effect+of+long-term+preservation+on+the+mechanical+properties+of+cortical+bone+in+goats.">Effect of long-term preservation on the mechanical properties of cortical bone in goats.</a> Acta Orthop. 79, 708-716 (2008).</li><li>Shaw, J. M., Hunter, S. A., Gayton, J. C., Boivin, G. P., Prayson, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Repeated+freeze-thaw+cycles+do+not+alter+the+biomechanical+properties+of+fibular+allograft+bone.">Repeated freeze-thaw cycles do not alter the biomechanical properties of fibular allograft bone.</a> Clin Orthop Relat Res. 470 (3), 937-943 (2012).</li><li>Topp, T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Embalmed+and+fresh+frozen+human+bones+in+orthopedic+cadaveric+studies:+which+bone+is+authentic+and+feasible?.">Embalmed and fresh frozen human bones in orthopedic cadaveric studies: which bone is authentic and feasible?.</a> Acta Orthop. 83 (5), 543-547 (2012).</li><li>Manske, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Cortical+and+trabecular+bone+in+the+femoral+neck+both+contribute+to+proximal+femur+failure+load+prediction.">Cortical and trabecular bone in the femoral neck both contribute to proximal femur failure load prediction.</a> Osteoporos Int. 20 (3), 445-453 (2009).</li><li>Rezaei, A., Dragomir-Daescu, D. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Femoral+Strength+Changes+Faster+With+Age+Than+BMD+in+Both+Women+and+Men:+A+Biomechanical+Study.">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>Cristofolini, L., McNamara, B., Freddi, A., Viceconti, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vitro+measured+strains+in+the+loaded+femur:+quantification+of+experimental+error.">In vitro measured strains in the loaded femur: quantification of experimental error.</a> J Strain Anal Eng Des. 32, 193-200 (1997).</li><li>Dragomir-Daescu, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Robust+QCT/FEA+models+of+proximal+femur+stiffness+and+fracture+load+during+a+sideways+fall+on+the+hip.">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></ol>

作者有没有相关的披露。

我们提出了确保臀部配置横盘下跌股力量力学测试和QCT / FEA建模一个强大的骨骼准备协议。这种方法成了我们的标准的内部协议。在6年的过程中，有不同的人员，成功制备出约200股骨下此协议。该协议的成果包括分类使用DXA骨条件下，排除了转移性疾病，先前的骨折，或利用X射线的植入物，并获得矿物分布和利用CT用于随后QCT / FEA建模的3D几何形状。切割，灌封，并且扫描装置被设计成容纳左和?...

Determining the true cadaveric proximal femoral fracture strength with mechanical testing is a destructive method that requires a rigorous testing approach for accurate measurements. In particular, proper bone preparation methods are necessary to maintain near in vivo integrity of the bones prior to mechanical fracture testing1. This is achieved by proper bone storage and minimizing handling at room temperature. This test data is extensively used to validate QCT/FEA models of femoral fracture which have the potential to be used clinically to understand the fracture risk, especially in osteoporotic patients. Unfortunately, there is no current standard procedure to prepare proximal femur samples for mechanical testing. A good testing procedure should ensure repeatability and reproducibility of the preparation process. Therefore, fixtures required for sample preparation need to be carefully designed and fabricated to minimize the likelihood of various testing errors. We also need to minimize the preparation time for which bone tissue is at room temperature and thus in danger of degradation with irreversible changes in mechanical properties. 
To this end, we have developed a procedure that preserves bone tissue across multiple preparation steps. This is important to ensure minimal exposure time at room temperature while also minimizing the number of freeze/thaw cycles which can affect tissue physical properties2. The entire procedure is long and nontrivial as the steps occurred over multiple weeks and required scheduling for scanning procedures and personnel availability. The steps included thawing bone samples, screening the samples using DXA scanning to obtain bone mineral density (BMD) values, X-ray to rule out any diseased specimens, and finally CT scanning to estimate distribution of bone mineral and femoral geometry. All the specimens were prepared for testing by removing extraneous soft tissues from the bone surface, cutting the femur to a length required for testing, and potting the femur in a desired orientation for simulating a sideways fall on the hip during subsequent testing. It is essential to keep the time period for all these operations as short as possible. A robust protocol is thus mandatory for consistent specimen preparation, tissue preservation between steps, and for reducing the overall preparation time. 
The aim of this paper is to present in detail the procedures involved in the preparation of femoral samples for subsequent mechanical testing under various conditions. Preservation of the bone tissue is crucial in this process and we achieved it by keeping specimens frozen between steps and keeping them carefully wrapped in saline saturated towels at all times except when scanning and mechanically testing the bones. Femora were also kept wrapped in saline wet towels during the steps involving PMMA curing to prevent dryness of the bone tissue.

<table><tbody><tr><td>CT potting container and scanning fixture</td><td>Internally manufactured</td><td>N/A</td><td>Custom designed and manufactured</td></tr><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>Dual Energy X-ray Absorptiometry scanner</td><td>General Electric</td><td>N/A</td><td>GE Lunar iDXA scanner for bone health or any similar BMD scanners</td></tr><tr><td>Hygenic Orhodontic 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 &amp;deg;C storage for bones</td></tr><tr><td>X-ray scanner</td><td>General Electric</td><td>&amp;nbsp;46-270615P1</td><td>X-ray imaging equipment.&amp;nbsp;&amp;nbsp;</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&amp;nbsp;</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>5-pound Rice Bags</td><td>Great Value</td><td>N/A&amp;nbsp;</td><td>Used for mimicking soft tissue during the DXA scanning process</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>Cast cutter</td><td>Stryker</td><td>810-BD001</td><td>Used to cut femoral shaft</td></tr><tr><td>Drilling machine</td><td>Bosch</td><td>N/A</td><td>Used to drill the femoral shaft</td></tr><tr><td>Fume Hood</td><td>Hamilton</td><td>70532</td><td>Used for ventilation when using making PMMA</td></tr></tbody></table>

proximal cadaveric femur preparation for fracture strength testing and quantitative ct-based finite element analysis

尸体断裂测试通常用来了解影响股骨近端强度的因素。由于体外生物组织很容易随着时间的推移失去其机械性能，样品必须仔细进行实验测试的准备，以获得在体内条件代表可靠的结果。出于这个原因，我们设计了一个协议和一套夹具以制备股骨标本，使得它们的机械性能经历最小的变化。在准备步骤和机械测试除股骨保持在冷冻状态。有临床双能X线骨密度仪（DXA）骨密度仪获得了全髋关节和股骨颈骨密度（BMD）的相关临床措施，并利用CT与校准幻影，获得三维几何和骨矿物质的分布基于所述灰度值的定量估计。任何可能的骨骼疾病，骨折，或植入物或影响骨结构的工件的情况下，被排除用X射线扫描。对于制备，所有的骨头被仔细清洗过量的软组织，并切断与盆栽在感兴趣的内部旋转角度。切割夹具允许骨的远端被切断而使股骨近端在所希望的长度。以允许以后的CT扫描和机械测试期间在规定的角度股骨颈定位，股骨近端的轴是在聚甲基丙烯酸甲酯（PMMA），使用专为所需的方向而设计的夹具盆栽。然后从我们的实验中收集的数据被用于定量计算机断层扫描（QCT）的验证为基础的有限元分析（FEA），如在不同的协议描述。在这个手稿中，我们提出了力学性能试验和随后的QCT / FEA建模精确的骨骼制备的协议。目前的协议已成功应用于准备约200 CADaveric股骨超过6年的时间。

该股骨尸体被运冷冻并保持在-20°C，直到准备开始了。使用DXA扫描仪测量每个样品（ 图1）全髋和颈部的BMD以及T分数进行骨密度扫描。 T-分数是所测量骨密度的标准偏差相比，年轻健康受试者的平均值的数量。它的范围可以从-2.5或更低骨质疏松筋骨，-1和-2.5之间的骨质疏松的骨骼和高于-1正常的骨头。一旦完成后，骨头被清洗多余的组织，切成使用一个内部?...

Watch this Scientific Journal Video about Proximal Cadaveric Femur Preparation for Fracture Strength Testing and Quantitative CT-based Finite Element Analysis at JoVE.com

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

我们提出了如何妥善保存，并准备测试断裂和定量计算机断层成像尸体股骨一个强大的协议。该方法提供了对用于确定骨矿物密度，断裂强度之间的关系，并限定有限元模型的几何形状和性能的目的输入条件的精确控制。

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 ...

proximal-cadaveric-femur-preparation-for-fracture-strength-testing

Universidad de Cartagena UDEC

Research

JoVE Journal

Medicine

9.2K 次观看.  Mayo Clinic. 我们提出了如何妥善保存，并准备测试断裂和定量计算机断层成像尸体股骨一个强大的协议。该方法提供了对用于确定骨矿物密度，断裂强度之间的关系，并限定有限元模型的几何形状和性能的目的输入条件的精确控制。 

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

Quantitative Autonomic Testing

Disorders associated with dysfunction of autonomic nervous system are quite common yet frequently unrecognized. Quantitative autonomic testing can be invaluable tool for evaluation of these disorders, both in clinic and research. There are number of autonomic tests, however, only few were validated clinically or are quantitative. Here, fully quantitative and clinically validated protocol for testing of autonomic functions is presented. As a bare minimum the clinical autonomic laboratory should have a tilt table, ECG monitor, continuous noninvasive blood pressure monitor, respiratory monitor and a mean for evaluation of sudomotor domain. The software for recording and evaluation of autonomic tests is critical for correct evaluation of data. The presented protocol evaluates 3 major autonomic domains: cardiovagal, adrenergic and sudomotor. The tests include deep breathing, Valsalva maneuver, head-up tilt, and quantitative sudomotor axon test (QSART). The severity and distribution of dysautonomia is quantitated using Composite Autonomic Severity Scores (CASS). Detailed protocol is provided highlighting essential aspects of testing with emphasis on proper data acquisition, obtaining the relevant parameters and unbiased evaluation of autonomic signals. The normative data and CASS algorithm for interpretation of results are provided as well.

Standardized, comprehensive and fully quantitative testing of autonomic functions is described. The autonomic tests consist of evaluation of all three major autonomic domains including cardiovagal, adrenergic and sudomotor. The severity and distribution of dysautonomia is quantitated using Composite Autonomic Severity Scores.

定量自主测试

Disorders associated with dysfunction of autonomic nervous system are quite common yet frequently unrecognized. Quantitative autonomic testing can be ...

科研

医学

Manual Muscle Testing:  A Method of Measuring Extremity Muscle Strength Applied to Critically Ill Patients

Survivors of acute respiratory distress syndrome (ARDS) and other causes of critical illness often have generalized weakness, reduced exercise tolerance, and persistent nerve and muscle impairments after hospital discharge.1-6 Using an explicit protocol with a structured approach to training and quality assurance of research staff, manual muscle testing (MMT) is a highly reliable method for assessing strength, using a standardized clinical examination, for patients following ARDS, and can be completed with mechanically ventilated patients who can tolerate sitting upright in bed and are able to follow two-step commands. 7, 8 
This video demonstrates a protocol for MMT, which has been taught to &ge;43 research staff who have performed &gt;800 assessments on &gt;280 ARDS survivors. Modifications for the bedridden patient are included. Each muscle is tested with specific techniques for positioning, stabilization, resistance, and palpation for each score of the 6-point ordinal Medical Research Council scale.7,9-11 Three upper and three lower extremity muscles are graded in this protocol: shoulder abduction, elbow flexion, wrist extension, hip flexion, knee extension, and ankle dorsiflexion. These muscles were chosen based on the standard approach for evaluating patients for ICU-acquired weakness used in prior publications. 1,2.

Survivors of acute respiratory distress syndrome (ARDS) and critical illness frequently develop long-lasting muscle weakness. Manual muscle testing (MMT) is a standardized clinical examination commonly used to measure strength of peripheral skeletal muscle groups. This video demonstrates MMT using the 6-point Medical Research Council scale.

危重病人中的应用手册肌力测试:下肢肌力测量方法

Survivors of acute respiratory distress syndrome (ARDS) and other causes of critical illness often have generalized weakness, reduced exercise tolerance, ...

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

Mechanical testing of femora brings valuable insights into understanding the contribution of clinically-measureable variables such as bone mineral density distribution and geometry on the femoral mechanical properties. Currently, there is no standard protocol for mechanical testing of such geometrically complex bones to measure strength, and stiffness. To address this gap we have developed a protocol to test cadaveric femora to fracture and to measure their biomechanical parameters. This protocol describes a set of adaptable fixtures to accommodate the various load magnitudes and directions accounting for possible bone orientations in a fall on the hip configuration, test speed, bone size, and left leg-right leg variations. The femora were prepared for testing by cleaning, cutting, scanning, and potting the distal end and greater trochanter contact surfaces in poly(methyl methacrylate) (PMMA) as presented in a different protocol. The prepared specimens were placed in the testing fixture in a position mimicking a sideways fall on the hip and loaded to fracture. During testing, two load cells measured vertical forces applied to the femoral head and greater trochanter, a six-axis load cell measured forces and moments at the distal femoral shaft, and a displacement sensor measured differential displacement between the femoral head and trochanter contact supports. High speed video cameras were used to synchronously record the sequence of fracture events during testing. The reduction of this data allowed us to characterize the strength, stiffness, and fracture energy for nearly 200 osteoporotic, osteopenic, and normal cadaveric femora for further development of engineering-based diagnostic tools for osteoporosis research.

In this manuscript, we present a protocol to fracture test cadaveric proximal femora in a sideways fall on the hip configuration using instrumented fixtures mounted on a standard servo hydraulic frame. Nine digitized signals comprising forces, moments, and displacement along with two high speed video streams are acquired during testing.

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 ...

生物工程

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 ...

A Simple Critical-sized Femoral Defect Model in Mice

While bone has a remarkable capacity for regeneration, serious bone trauma often results in damage that does not properly heal. In fact, one tenth of all limb bone fractures fail to heal completely due to the extent of the trauma, disease, or age of the patient. Our ability to improve bone regenerative strategies is critically dependent on the ability to mimic serious bone trauma in test animals, but the generation and stabilization of large bone lesions is technically challenging. In most cases, serious long bone trauma is mimicked experimentally by establishing a defect that will not naturally heal. This is achieved by complete removal of a bone segment that is larger than 1.5 times the diameter of the bone cross-section. The bone is then stabilized with a metal implant to maintain proper orientation of the fracture edges and allow for mobility. 
Due to their small size and the fragility of their long bones, establishment of such lesions in mice are beyond the capabilities of most research groups. As such, long bone defect models are confined to rats and larger animals. Nevertheless, mice afford significant research advantages in that they can be genetically modified and bred as immune-compromised strains that do not reject human cells and tissue.
Herein, we demonstrate a technique that facilitates the generation of a segmental defect in mouse femora using standard laboratory and veterinary equipment. With practice, fabrication of the fixation device and surgical implantation is feasible for the majority of trained veterinarians and animal research personnel. Using example data, we also provide methodologies for the quantitative analysis of bone healing for the model.

Animal models are frequently employed to mimic serious bone injury in biomedical research. Due to their small size, establishment of stabilized bone lesions in mice are beyond the capabilities of most research groups. Herein, we describe a simple method for establishing and analyzing experimental femoral defects in mice.

一个简单的临界尺寸股骨缺损模型小鼠

While bone has a remarkable capacity for regeneration, serious bone trauma often results in damage that does not properly heal. In fact, one tenth of all ...

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

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 ...

Fracture Apparatus Design and Protocol Optimization for Closed-stabilized Fractures in Rodents

The reliable generation of consistent stabilized fractures in animal models is essential for understanding the biology of bone regeneration and developing therapeutics and devices. However, available injury models are plagued by inconsistency resulting in wasted animals and resources and imperfect data. To address this problem of fracture heterogeneity, the purpose of the method described herein is to optimize fracture generation parameters specific to each animal and yield a consistent fracture location and pattern. This protocol accounts for variations in bone size and morphology that may exist between mouse strains and can be adapted to generate consistent fractures in other species, such as rat. Additionally, a cost-effective, adjustable fracture apparatus is described. Compared to current stabilized fracture techniques, the optimization protocol and new fracture apparatus demonstrate increased consistency in stabilized fracture patterns and locations. Using optimized parameters specific to the sample type, the described protocol increases the precision of induced traumas, minimizing the fracture heterogeneity typically observed in closed-fracture generation procedures.

The goal of the protocol is to optimize the fracture generation parameters to yield consistent fractures. This protocol accounts for the variations in bone size and morphology that may exist between animals. Additionally, a cost-effective, adjustable fracture apparatus is described.

鼠类闭合稳定骨折的断裂装置设计与协议优化

The reliable generation of consistent stabilized fractures in animal models is essential for understanding the biology of bone regeneration and developing ...

骨折易感性机械测试的原则和方案

Practical Considerations for the Design, Execution, and Interpretation of Studies Involving Whole-Bone Bending Tests of Rodent Bones

Skeletal fragility leading to fracture is an American public health crisis resulting in 1.5 million fractures each year and $18 billion in direct care costs. The ability to understand the mechanisms underlying bone disease and the response to treatment is not only desired, but critical. Mechanical testing of bone serves as a valuable technique for understanding and quantifying a bone&#39;s susceptibility to fracture. While this method appears simple to perform, inappropriate and inaccurate conclusions may be reached if governing assumptions and key steps are disregarded by the user. This has been observed across disciplines as studies continue to be published with misuse of methods and incorrect interpretation of results. This protocol will serve as a primer for the principles associated with mechanical testing along with the application of these techniques-from considerations of sample size through tissue harvesting and storage, to data analysis and interpretation. With this in hand, valuable information regarding a bone&#39;s susceptibility to fracture may be obtained, furthering understanding for both academic research and clinical solutions.

作者聚焦：提高全骨弯曲测试的准确性和可重复性 

Mechanical testing of rodent bones is a valuable method for extracting information regarding a bone's susceptibility to fracture. Lacking proper practical understanding, the results may be overinterpreted or lack validity. This protocol will serve as a guide to ensure mechanical tests are performed accurately to provide valid and functional data.

设计、执行和解释涉及啮齿动物骨骼全骨弯曲试验的研究的实际考虑因素

Skeletal fragility leading to fracture is an American public health crisis resulting in 1.5 million fractures each year and $18 billion in direct care ...

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

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定量自主测试

危重病人中的应用手册肌力测试:下肢肌力测量方法

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

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

一个简单的临界尺寸股骨缺损模型小鼠

人髋关节微观结构失效机制的成像

鼠股颈悬臂弯曲

鼠类闭合稳定骨折的断裂装置设计与协议优化

设计、执行和解释涉及啮齿动物骨骼全骨弯曲试验的研究的实际考虑因素

设计、执行和解释涉及啮齿动物骨骼全骨弯曲试验的研究的实际考虑因素