Optimised loads for the simulation of axial rotation in the lumbar spine
Optimised loads for the simulation of axial rotation in the lumbar spine
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DOI：
10.1016/j.jbiomech.2011.05.040
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发表时间：
2011-08-11
影响因子：
2.4
通讯作者：
Zander, Thomas
中科院分区：
文献类型：
--
作者：
Dreischarf, Marcel;Rohlmann, Antonius;Zander, Thomas
在体外研究中，通常采用简化的加载模式（纯力矩、压缩力）来模拟脊柱的屈伸、侧弯和轴向旋转。文献中轴向旋转的载荷大小变化很大。因此，当前研究的结果（例如椎间旋转）几乎没有可比性，并且可能涉及不切实际的值。因此，“哪种体外适用的加载模式最现实”的问题仍然是开放的。在两项敏感性研究中，采用了经验证的腰椎有限元模型，以估计由于已发表的载荷假设导致的结果范围，并确定输入参数（例如扭矩），这些参数主要影响轴向旋转期间的脊柱载荷和运动学。在随后的优化研究中，确定了体外适用的加载模式，该模式提供的结果与现有的体内测量结果最佳拟合。对于文献中使用的载荷，计算结果差异很大，与体内测量值可能存在很大偏差。椎间盘内压力主要受压缩力大小的影响，而扭矩主要影响椎间旋转和小关节力。当随动器压力为720 N，纯力矩为5.5 Nm时，L1椎体的轴向旋转与体内测量结果吻合最好。结果表明，在许多研究中，假设的载荷并不能真实地模拟轴向旋转。体外适用的简化载荷不能完全模拟体内情况。然而，优化值导致与体内测量值的最佳一致性。随后适用这些标准将使不同的调查具有更好的可比性。(C)2011爱思唯尔有限公司保留所有权利。
Simplified loading modes (pure moment, compressive force) are usually applied in the in vitro studies to simulate flexion-extension, lateral bending and axial rotation of the spine. The load magnitudes for axial rotation vary strongly in the literature. Therefore, the results of current investigations, e.g. intervertebral rotations, are hardly comparable and may involve unrealistic values. Thus, the question 'which in vitro applicable loading mode is the most realistic' remains open.A validated finite element model of the lumbar spine was employed in two sensitivity studies to estimate the ranges of results due to published load assumptions and to determine the input parameters (e.g. torsional moment), which mostly affect the spinal load and kinematics during axial rotation. In a subsequent optimisation study, the in vitro applicable loading mode was determined, which delivers results that fit best with available in vivo measurements.The calculated results varied widely for loads used in the literature with potential high deviations from in vivo measured values. The intradiscal pressure is mainly affected by the magnitude of the compressive force, while the torsional moment influences mainly the intervertebral rotations and facet joint forces. The best agreement with results measured in vivo were found for a compressive follower force of 720 N and a pure moment of 5.5 Nm applied to the unconstrained vertebra L1.The results reveal that in many studies the assumed loads do not realistically simulate axial rotation. The in vitro applicable simplified loads cannot perfectly mimic the in vivo situation. However, the optimised values lead to the best agreement with in vivo measured values. Their consequent application would lead to a better comparability of different investigations. (C) 2011 Elsevier Ltd. All rights reserved.