Static and fatigue biomechanical properties of anterior thoracolumbar instrumentation systems - A synthetic testing model
Static and fatigue biomechanical properties of anterior thoracolumbar instrumentation systems - A synthetic testing model
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DOI：
10.1097/00007632-199907150-00004
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发表时间：
1999-07-15
期刊：
影响因子：
3
通讯作者：
McAfee, PC
中科院分区：
文献类型：
--
作者：
Kotani, Y;Cunningham, BW;McAfee, PC
研究设计。介绍了一种用于胸腰椎前路内固定系统的力学测试标准，采用综合模型。12个最新的仪器系统在静态和疲劳模式下进行了测试。建立胸腰椎前路内固定系统综合模型的测试标准，评价12个胸腰椎前路内固定系统的静态和疲劳生物力学性能。虽然已有大量研究利用身体或动物组织评估脊柱前路内固定的生物力学，但也指出了标本多样性、缺乏重复性和无法进行疲劳测试的问题。目前尚无研究描述胸腰椎前路内固定系统的精确综合测试标准。根据椎体的解剖尺寸设计了一种超高相对分子质量的聚乙烯圆柱体。通过脊柱内固定装置跨越的两个圆柱体模拟全椎体切除的缺损区，施加压缩侧向弯曲载荷。仪器装配是精确标准化的。在三种载荷水平下进行了长达200万次的静力破坏和疲劳试验，并进行了失效模式分析。12个前路内固定系统，包括5个钢板和7个棒系统，在刚度、弯曲强度和失败次数方面进行了比较。静态和疲劳测试参数都显示设备之间存在非常显著的差异。在辛迪斯钢板(辛迪斯，保利，宾夕法尼亚州)到Z-PLATE AN(索法莫-丹内克，孟菲斯，田纳西州)，刚度从280.5 kN/m到67.9kN/m不等。Synths钢板和Kaneda SR钛(AcroMed，克利夫兰，俄亥俄州)的弯曲强度最高，分别为1516.1 N和1209.9 N，而Z形钢板的弯曲强度最低，为407.3 N。疲劳试验中，只有Synths钢板、Kaneda SR钛和Olerud钢板(Nord Opedic AB，瑞典)在600N下经受了200万次循环。失效模式分析显示，钢板系统的钢板或螺栓断裂，杆件系统的杆件断裂。成功设计了胸腰椎前路内固定系统生物力学测试标准。它提供了一个可重复和一致的实验条件，并控制了尺寸和手术因素。对12种仪表系统的比较突出了机械平衡装置设计的重要性，在仪表的发展中没有薄弱环节。
Study Design. A mechanical testing standard for anterior thoracolumbar instrumentation systems was introduced, using a synthetic model. Twelve recent instrumentation systems were tested in static and fatigue modes.Objectives. To establish the testing standard for anterior thoracolumbar instrumentation systems using a synthetic model and to evaluate the static and fatigue biomechanical properties of 12 anterior thoracolumbar instrumentation systems.Summary of Background Data. Although numerous studies have been performed to evaluate the biomechanics of anterior spinal instrumentation using a cadaveric or animal tissue, problems of specimen variation, lack of reproducibility, and inability to perform fatigue testing have been pointed out. In no studies has a precise synthetic testing standard for anterior thoracolumbar instrumentation systems been described.Methods. An ultra-high-molecular-weight polyethylene cylinder was designed according to the anatomic dimensions of the vertebral body. Two cylinders spanned by spinal instrumentation simulated a total corpectomy defect, and a compressive lateral bending load was applied. The instrumentation assembly was precisely standardized. The static destructive and fatigue tests up to 2 million cycles at three load levels were conducted, followed by the failure mode analysis. Twelve anterior instrumentation systems, consisting of five plate and seven rod systems were compared in stiffness, bending strength, and cycles to failure.Results. Static and fatigue test parameters both demonstrated highly significant differences between devices. The stiffness ranged from 280.5 kN/m in the Synthes plate (Synthes, Paoli, PA) to 67.9 kN/m in the Z-plate An (Sofamor-Danek, Memphis, TN). The Synthes plate and Kaneda SR titanium (AcroMed, Cleveland, OH) formed the highest subset in bending strength of 1516.1 N and 1209.9 N, respectively, whereas the Z-plate showed the lowest value of 407.3 N. There were no substantial differences between plate and rod devices. In fatigue, only three systems: Synthes plate, Kaneda SR titanium, and Olerud plate (Nord Opedic AB, Sweden) withstood 2 million cycles at 600 N. The failure mode analysis demonstrated plate or bolt fractures in plate systems and rod fractures in rod systems.Conclusions. The biomechanical testing standard for anterior thoracolumbar instrumentation systems was successfully designed. It provided a repeatable and consistent experimental condition and controlling dimensional and surgical factors. The comparison of 12 instrumentation systems highlights the importance of mechanically balanced device design without a weak link in the development of instrumentation.