Phuntsok Rinchen, Mazur Marcus D, Ellis Benjamin J, Ravindra Vijay M, Brockmeyer Douglas L
Department of Bioengineering and Scientific Computing and Imaging Institute, University of Utah; and.
Department of Neurosurgery, Division of Pediatric Neurosurgery, University of Utah, Primary Children's Hospital, Salt Lake City, Utah.
J Neurosurg Pediatr. 2016 Apr;17(4):497-503. doi: 10.3171/2015.8.PEDS15334. Epub 2015 Dec 18.
OBJECT There is a significant deficiency in understanding the biomechanics of the pediatric craniocervical junction (CCJ) (occiput-C2), primarily because of a lack of human pediatric cadaveric tissue and the relatively small number of treated patients. To overcome this deficiency, a finite element model (FEM) of the pediatric CCJ was created using pediatric geometry and parameterized adult material properties. The model was evaluated under the physiological range of motion (ROM) for flexion-extension, axial rotation, and lateral bending and under tensile loading. METHODS This research utilizes the FEM method, which is a numerical solution technique for discretizing and analyzing systems. The FEM method has been widely used in the field of biomechanics. A CT scan of a 13-month-old female patient was used to create the 3D geometry and surfaces of the FEM model, and an open-source FEM software suite was used to apply the material properties and boundary and loading conditions and analyze the model. The published adult ligament properties were reduced to 50%, 25%, and 10% of the original stiffness in various iterations of the model, and the resulting ROMs for flexion-extension, axial rotation, and lateral bending were compared. The flexion-extension ROMs and tensile stiffness that were predicted by the model were evaluated using previously published experimental measurements from pediatric cadaveric tissues. RESULTS The model predicted a ROM within 1 standard deviation of the published pediatric ROM data for flexion-extension at 10% of adult ligament stiffness. The model's response in terms of axial tension also coincided well with published experimental tension characterization data. The model behaved relatively stiffer in extension than in flexion. The axial rotation and lateral bending results showed symmetric ROM, but there are currently no published pediatric experimental data available for comparison. The model predicts a relatively stiffer ROM in both axial rotation and lateral bending in comparison with flexion-extension. As expected, the flexion-extension, axial rotation, and lateral bending ROMs increased with the decrease in ligament stiffness. CONCLUSIONS An FEM of the pediatric CCJ was created that accurately predicts flexion-extension ROM and axial force displacement of occiput-C2 when the ligament material properties are reduced to 10% of the published adult ligament properties. This model gives a reasonable prediction of pediatric cervical spine ligament stiffness, the relationship between flexion-extension ROM, and ligament stiffness at the CCJ. The creation of this model using open-source software means that other researchers will be able to use the model as a starting point for research.
目的:在理解小儿颅颈交界区(CCJ,枕骨 - C2)的生物力学方面存在显著不足,主要原因是缺乏小儿尸体组织以及接受治疗的患者数量相对较少。为克服这一不足,利用小儿几何形状和参数化的成人材料特性创建了小儿CCJ的有限元模型(FEM)。在屈伸、轴向旋转和侧方弯曲的生理运动范围(ROM)以及拉伸载荷下对该模型进行了评估。方法:本研究采用有限元法,这是一种用于离散化和分析系统的数值求解技术。有限元法在生物力学领域已被广泛应用。使用一名13个月大女性患者的CT扫描数据创建有限元模型的三维几何形状和表面,并使用开源有限元软件套件来应用材料特性、边界条件和载荷条件以及分析模型。在模型的各种迭代中,将已发表的成人韧带特性降低至原始刚度的50%、25%和10%,并比较屈伸、轴向旋转和侧方弯曲产生的ROM。使用先前发表的小儿尸体组织实验测量数据评估模型预测的屈伸ROM和拉伸刚度。结果:在成人韧带刚度为10%时,该模型预测的屈伸ROM在已发表的小儿ROM数据的1个标准差范围内。该模型在轴向拉伸方面的响应也与已发表的实验拉伸特性数据吻合良好。该模型在伸展时表现得比屈曲时相对更硬。轴向旋转和侧方弯曲结果显示出对称的ROM,但目前尚无已发表的小儿实验数据可供比较。与屈伸相比,该模型预测轴向旋转和侧方弯曲时的ROM相对更硬。正如预期的那样,屈伸、轴向旋转和侧方弯曲的ROM随着韧带刚度的降低而增加。结论:创建了小儿CCJ的有限元模型,并在将韧带材料特性降低至已发表的成人韧带特性的10%时,该模型能够准确预测枕骨 - C2的屈伸ROM和轴向力位移。该模型对小儿颈椎韧带刚度、屈伸ROM与CCJ处韧带刚度之间的关系给出了合理预测。使用开源软件创建此模型意味着其他研究人员将能够以该模型为研究起点。
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