Effect of an artificial disc on lumbar spine biomechanics: a probabilistic finite element study
Effect of an artificial disc on lumbar spine biomechanics: a probabilistic finite element study
复制标题
人工椎间盘对腰椎生物力学的影响：概率有限元研究
DOI：
10.1007/s00586-008-0836-1
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发表时间：
2008
影响因子：
2.8
通讯作者：
G. Bergmann
中科院分区：
文献类型：
--
作者：
A. Rohlmann;A. Mann;T. Zander;G. Bergmann
在大多数情况下，不同参数对腰椎机械行为的影响是确定性确定的，每次只有一个不确定参数变化，而其他参数保持固定。因此，大多数参数组合被忽略。该研究的目的是在概率有限元研究中确定椎间旋转、椎间盘内压力和小关节中的接触力如何受到输入参数植入物位置、植入球半径、疤痕组织的存在和小关节中的间隙尺寸的影响。使用从L3椎骨到L5/S1椎间盘的腰椎骨韧带有限元模型。将具有固定旋转中心的人造椎间盘插入 L4/L5 平面。该模型加载了 7.5 Nm 的纯力矩来模拟弯曲、伸展、侧向弯曲和轴向扭转。在一项概率研究中，前后 (ap) 和横向方向的种植体位置、种植体球的半径以及小关节的间隙大小是不同的。植入人工椎间盘后，可能会形成疤痕组织，取代前纵韧带。因此也模拟了疤痕组织的存在和不存在。对于所研究的每个负载情况，计算 1,000 个随机输入参数组合的椎间旋转、椎间盘内压力和小关节中的接触力，以确定这些输出参数的可能范围。对于不同的输入参数组合，植入物水平的椎间旋转变化很大。它主要受间隙尺寸、AP 位置和弯曲的植入球半径的影响，延伸和侧向弯曲的主要受疤痕组织和植入球半径的影响，以及轴向扭转的间隙尺寸和植入球半径的影响。对于伸展，种植体水平的椎间旋转在 1.4° 到 7.5° 之间变化。相邻椎间盘中的椎间盘内压力仅受所有输入参数的轻微影响。对于输入参数的不同组合，种植体层面小关节中的接触力变化很大。对于屈曲，63% 的情况下力为 0，但对于小间隙尺寸和大种植体球半径，它们的值高达 533 N。对于最大预测力为 560 N 的伸展，也发现了类似的结果。这里的力主要受到间隙尺寸、种植体球半径和疤痕组织的影响。横向弯曲的力在 0 到 300 N 之间变化，轴向扭转的力在 0 到 200 N 之间变化。在两种载荷情况下影响最大的参数与延伸参数相同。小关节中的椎间旋转和接触力很大程度上取决于所研究的输入参数。概率研究显示结果和某些值的可能性存在很大差异。需要进行临床研究来证明参数组合是否存在很强的相关性，这些参数组合会导致全椎间盘置换术后小关节高力和腰痛。
The effects of different parameters on the mechanical behaviour of the lumbar spine were in most cases determined deterministically with only one uncertain parameter varied at a time while the others were kept fixed. Thus most parameter combinations were disregarded. The aim of the study was to determine in a probabilistic finite element study how intervertebral rotation, intradiscal pressure, and contact force in the facet joints are affected by the input parameters implant position, implant ball radius, presence of scar tissue, and gap size in the facet joints. An osseoligamentous finite element model of the lumbar spine ranging from L3 vertebra to L5/S1 intervertebral disc was used. An artificial disc with a fixed center of rotation was inserted at level L4/L5. The model was loaded with pure moments of 7.5 Nm to simulate flexion, extension, lateral bending, and axial torsion. In a probabilistic study the implant position in anterior–posterior (ap) and in lateral direction, the radius of the implant ball, and the gap size of the facet joint were varied. After implanting an artificial disc, scar tissue may develop, replacing the anterior longitudinal ligament. Thus presence and absence of scar tissue were also simulated. For each loading case studied, intervertebral rotations, intradiscal pressures and contact forces in the facet joints were calculated for 1,000 randomized input parameter combinations in order to determine the probable range of these output parameters. Intervertebral rotation at implant level varies strongly for different combinations of the input parameters. It is mainly affected by gap size, ap-position and implant ball radius for flexion, by scar tissue and implant ball radius for extension and lateral bending, and by gap size and implant ball radius for axial torsion. For extension, intervertebral rotation at implant level varied between 1.4° and 7.5°. Intradiscal pressure in the adjacent discs is only slightly affected by all input parameters. Contact forces in the facet joints at implant level vary strongly for the different combinations of the input parameters. For flexion, forces are 0 in 63% of the cases, but for small gap sizes and large implant ball radii they reach values of up to 533 N. Similar results are found for extension with a maximum predicted force of 560 N. Here the forces are mainly influenced by gap size, implant ball radius and scar tissue. The forces vary between 0 and 300 N for lateral bending and between 0 and 200 N for axial torsion. The parameters that have the greatest effect in both loading cases are the same as those for extension. Intervertebral rotation and contact force in the facet joints depend strongly on the input parameters studied. The probabilistic study shows a large variation of the results and likelihood of certain values. Clinical studies will be required to show whether or not there is a strong correlation of parameter combinations that cause high facet joint forces and low back pain after total disc replacement.