Kotani Y, Cunningham B W, Parker L M, Kanayama M, McAfee P C
Department of Orthopaedic Surgery, Union Memorial Hospital, Baltimore, Maryland, USA.
Spine (Phila Pa 1976). 1999 Jul 15;24(14):1406-13. doi: 10.1097/00007632-199907150-00004.
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.
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.
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.
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.
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 ATL (SofamorDanek, 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.
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.
引入了一种用于胸腰椎前路内固定系统的机械测试标准，采用合成模型。对12种最新的内固定系统进行了静态和疲劳模式测试。
使用合成模型建立胸腰椎前路内固定系统的测试标准，并评估12种胸腰椎前路内固定系统的静态和疲劳生物力学特性。
尽管已经进行了大量研究以评估使用尸体或动物组织的脊柱前路内固定的生物力学，但标本变异、缺乏可重复性以及无法进行疲劳测试等问题已被指出。尚无研究描述胸腰椎前路内固定系统精确的合成测试标准。
根据椎体的解剖尺寸设计了一个超高分子量聚乙烯圆柱体。由脊柱内固定跨越的两个圆柱体模拟了全椎体切除缺损，并施加了压缩侧方弯曲载荷。内固定组件进行了精确标准化。在三个载荷水平下进行了高达200万次循环的静态破坏和疲劳测试，随后进行了失效模式分析。比较了由五种钢板和七种棒材系统组成的12种前路内固定系统在刚度、抗弯强度和失效循环次数方面的差异。
静态和疲劳测试参数在不同装置之间均显示出高度显著差异。刚度范围从Synthes钢板（Synthes，Paoli，PA）的280.5 kN/m到Z-plate ATL（SofamorDanek，Memphis，TN）的67.9 kN/m。Synthes钢板和Kaneda SR钛合金（AcroMed，Cleveland，OH）在抗弯强度方面分别形成了最高子集，值为1516.1 N和1209.9 N，而Z-plate显示出最低值407.3 N。钢板和棒材装置之间没有实质性差异。在疲劳测试中，只有三种系统：Synthes钢板、Kaneda SR钛合金和Olerud钢板（Nord Opedic AB，瑞典）在600 N下承受了200万次循环。失效模式分析表明钢板系统中出现钢板或螺栓断裂，棒材系统中出现棒材断裂。
成功设计了胸腰椎前路内固定系统的生物力学测试标准。它提供了可重复且一致的实验条件，并控制了尺寸和手术因素。对12种内固定系统的比较突出了在器械开发中机械平衡装置设计且无薄弱环节的重要性。
