Goel Vijay K, Grauer Jonathan N, Patel Tushar Ch, Biyani Ashok, Sairyo Koichi, Vishnubhotla Srilakshmi, Matyas Aaron, Cowgill Ian, Shaw Miranda, Long Rebecca, Dick David, Panjabi Manohar M, Serhan Hassan
Spine Research Center, University of Toledo and Medical University of Ohio, Toledo, OH 43606, USA.
Spine (Phila Pa 1976). 2005 Dec 15;30(24):2755-64. doi: 10.1097/01.brs.0000195897.17277.67.
Finite element model of L3-S1 segment and confirmatory cadaveric testing were used to investigate the biomechanical effects of a mobile core type artificial disc (Charité artificial disc; DePuy Spine, Raynham, MA) on the lumbar spine.
To determine the effects of the Charité artificial disc across the implanted and adjacent segments.
Biomechanical studies of artificial discs that quantify parameters, like the load sharing and stresses, are sparse in the literature, especially for mobile-type core artificial disc designs. In addition, there is no standard protocol for studying the adjacent segmental effects of such implants.
Human osteo-ligamentous spines (L1-S1) were tested before and after L5-S1 Charité artificial disc placement. The data were used to validate further an intact 3-dimensional (3-D) nonlinear L3-S1 finite element model. The model was subjected to 400-N axial compression and 10.6 Nm of flexion/extension pure moments (load control) or pure moments that produced the overall rotation of the L3-S1 Charité model equal to the intact case (hybrid approach). Resultant motion, load, and stress parameters were analyzed at the experimental and adjacent levels.
Finite element model validation was achieved only with the load-controlled experiments. The hybrid approach, believed to be more clinically relevant, revealed that Charité artificial disc leads to motion increases in flexion (19%) and extension (44%) at the L5-S1 level. At the instrumented level, the decrease in the facet loads was less than at the adjacent levels; the corresponding decrease being 26% at L3-L4, 25% at L4-L5, and 13.4% at L5-S1 when compared to the intact. Intradiscal pressure changes in the L4-L5 and L3-L4 segments were minimal. Shear stresses at the Charité artificial disc-L5 endplate interface were higher than those at S1 interface. However, in the load control mode, the increase in facet loads in extension was approximately 14%, as compared to the intact case.
The hybrid testing protocol is advocated because it better reproduces clinical observations in terms of motion following surgery, using pure moments. Using this approach, we found that the Charité artificial disc placement slightly increases motion at the implanted level, with a resultant increase in facet loading when compared to the adjacent segments, while the motions and loads decrease at the adjacent levels. However, in the load control mode that we believe is not that clinically relevant, there was a large increase in motion and a corresponding increase in facet loads, as compared to the intact.
采用L3 - S1节段的有限元模型和尸体验证试验，来研究一种可动核心型人工椎间盘（Charité人工椎间盘；DePuy Spine公司，美国马萨诸塞州雷纳姆）对腰椎的生物力学影响。
确定Charité人工椎间盘对植入节段及相邻节段的影响。
文献中关于人工椎间盘生物力学的研究较少，这些研究量化了诸如负荷分担和应力等参数，特别是对于可动核心型人工椎间盘设计。此外，对于研究此类植入物的相邻节段效应，尚无标准方案。
在L5 - S1节段植入Charité人工椎间盘前后，对人体骨韧带脊柱（L1 - S1）进行测试。这些数据用于进一步验证完整的三维（3 - D）非线性L3 - S1有限元模型。该模型承受400 N的轴向压缩以及10.6 Nm的屈伸纯力矩（负荷控制），或使L3 - S1 Charité模型的整体旋转与完整情况相等的纯力矩（混合方法）。在实验节段和相邻节段分析合成运动、负荷和应力参数。
仅通过负荷控制实验实现了有限元模型验证。混合方法被认为更具临床相关性，结果显示Charité人工椎间盘使L5 - S1节段在屈曲时运动增加19%，伸展时运动增加44%。在植入节段，小关节负荷的降低小于相邻节段；与完整情况相比，L3 - L4节段相应降低26%，L4 - L5节段降低25%，L5 - S1节段降低13.4%。L4 - L5和L3 - L4节段的椎间盘内压力变化最小。Charité人工椎间盘 - L5终板界面处的剪应力高于S1界面处。然而，在负荷控制模式下，与完整情况相比，伸展时小关节负荷增加约14%。
提倡采用混合测试方案，因为它使用纯力矩能更好地再现术后运动方面的临床观察结果。采用这种方法，我们发现Charité人工椎间盘植入后，植入节段的运动略有增加，与相邻节段相比，小关节负荷相应增加，而相邻节段的运动和负荷则降低。然而，在我们认为与临床相关性不大的负荷控制模式下，与完整情况相比，运动大幅增加，小关节负荷相应增加。
