A biomechanical study of regional endplate strength and cage morphology as it relates to structural interbody support
A biomechanical study of regional endplate strength and cage morphology as it relates to structural interbody support
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DOI：
10.1097/01.brs.0000143623.18098.e5
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发表时间：
2004-11-01
期刊：
影响因子：
3
通讯作者：
Trommeter, J
中科院分区：
文献类型：
--
作者：
Lowe, TG;Hashim, S;Trommeter, J
研究设计.一项体外生物力学研究，旨在量化胸腰椎终板对压缩载荷的抵抗力。通过比较确定终板的区域强度、椎间支撑的最佳尺寸和几何形状以及终板切除对结构强度的影响。从生物力学角度评估胸腰椎终板强度的区域变化、结构性椎体间支撑的最佳几何形状和横截面积，以及终板准备技术对终板失效或下沉的影响。前柱椎体间支撑在脊柱重建中起着重要作用。椎体间结构支撑下沉是一个常见问题，可能与终板的局部薄弱、结构支撑的尺寸和/或几何形状以及终板的准备有关。与这些问题相关的生物力学数据对脊柱外科医生来说非常重要，可以降低下沉的风险及其固有的并发症。压痕试验分三个小组进行，每个小组有一组不同的试验变量。第一个测试包括使用9.53 mm直径压头在6个不同终板测试位置的65个椎骨。第二个测试在48个椎骨的中央终板测试部位使用不同直径的三个空心和两个实心圆柱形压头进行。第三个测试使用24个椎骨完成，终板完整，部分切除或完全切除。所有试验均使用人尸体标本，同时使用上级和下级终板。确定了每次试验的最大失效载荷（MLF）。对于所有测试节段，最高MLF发生在终板的后外侧区域。最低值分别出现在T7-L5和T1-T6节段的中央和前中央区域。小直径的空心压头的MLF最低，而实心大直径压头的MLF最高。所有空心压头的极限抗压强度明显高于所有实心压头。随着终板的完全去除，终板强度显着降低。结论。终板的后外侧区域提供最大的下沉阻力，而中心区域提供最小的阻力。较大直径的固体支撑物具有较大的MLF和较低的下沉风险，这表明使用中空压头将力更有效地传递到终板。结构支撑的几何形状以及终板的位置和准备等参数可能会影响椎间支撑下沉的阻力。部分切除终板既可获得足够的机械优势，又可提供高度血管化的融合部位。
Study Design. An in vitro biomechanical investigation to quantify the endplates resistance to compressive loads, in the thoracic and lumbar spine. Comparisons were made to determine the regional strength of the endplate, the optimal size and geometry of interbody support, and the effects of endplate removal on structural strength.Objectives. To biomechanically assess the regional variation of endplate strength in the thoracic and lumbar spine, the optimal geometry and cross-sectional area for structural interbody support, and endplate preparation techniques with respect to endplate failure or subsidence.Summary of Background Data. Anterior column interbody support plays an important role in spinal reconstruction. Subsidence of interbody structural support is a common problem and may be related to regional weakness of the endplate, the size and/or geometry of structural support, and the preparation of the endplate. Biomechanical data related to these issues should be of importance to spine surgeons and reduce the risk of subsidence and its inherent complications.Methods. The indentation tests were performed in three subgroups, each with a different set of test variables. The first test consisted of 65 vertebrae at six different endplate test positions using a 9.53-mm diameter indenter. The second test was performed on 48 vertebrae at a central endplate test site using three hollow and two solid cylindrical indenters of varying diameter. The third test was done using 24 vertebrae with the endplate intact, partially removed, or fully removed. All tests were run using human cadaveric specimen using both the superior and inferior endplates. The maximum load to failure (MLF) was determined for each test performed.Results. For all levels tested, the highest MLF occurred in the posterolateral region of the endplate. The lowest value occurred in the central and anterocentral regions for levels T7-L5 and T1-T6, respectively. Hollow indenters with a small diameter had the lowest MLF, whereas solid large-diameter indenters had the highest MLF. The ultimate compressive strength for all hollow indenters was significantly higher than all solid indenters. There was a significant reduction in the endplate strength with the complete removal of the endplate.Conclusions. The posterolateral region of the endplate provides the greatest resistance to subsidence while the central region provides the least resistance. A larger-diameter solid support has the greater MLF and the lower the risk of subsidence, suggesting a more efficient transfer of force to the endplate with the hollow indenters. Parameters such as the geometry of structural support and the position and preparation of the endplate can influence the resistance of an interbody support to subside. Partial removal of the endplate may provide both, for adequate mechanical advantage and a highly vascular site for fusion.