Department of Mechanical and Aeronautical Engineering, Clarkson University, 8 Clarkson Ave, Box 5725, Potsdam, NY, 13699, USA.
Biomech Model Mechanobiol. 2019 Oct;18(5):1363-1369. doi: 10.1007/s10237-019-01150-4. Epub 2019 Apr 12.
There is a growing interest in the development of patient-specific finite element models of the human lumbar spine for both the assessment of injury risk and the development of treatment strategies. A current challenge in implementing these models is that the outer annulus fibrosus of the disc is composed of concentric sheets of aligned collagen fibers, the helical angles of which vary spatially. In finite element models, fiber angle is typically assumed to be constant, based on average experimental measurements from a small number of locations. The present study hypothesized that the full spatial distribution of fiber angles in the annulus fibrosus may be predicted for any disc geometry by assuming growth from a thin cylinder with constant fiber angle. This hypothesis was tested by developing an analytical model of disc growth and calibrating it with fiber angle measurements of adult bovine caudal discs. The calibrated model was then run on a representative human lumbar disc geometry. The model was able to accurately predict fiber angle distributions in both the experimental bovine caudal disc measurements and literature-reported human lumbar disc measurements. Despite its theoretical basis in development, the model requires only mature state geometry, making it practical for implementation in patient-specific finite element analyses, in which disc geometry is obtained from clinical imaging.
人们越来越关注开发用于评估损伤风险和制定治疗策略的人类腰椎的个性化有限元模型。在实施这些模型时，一个当前的挑战是椎间盘的外环纤维由排列整齐的胶原纤维的同心层组成，其螺旋角在空间上发生变化。在有限元模型中，纤维角通常基于少数几个位置的平均实验测量值，被假设为常数。本研究假设，通过假设从具有恒定纤维角的薄壁圆柱体生长，可以预测任何椎间盘几何形状的外环纤维的完整空间分布。通过开发椎间盘生长的分析模型并对成年牛尾椎间盘的纤维角测量值进行校准来验证该假设。然后，将校准后的模型应用于代表性的人类腰椎间盘几何形状。该模型能够准确预测实验牛尾椎间盘测量值和文献报道的人类腰椎间盘测量值中的纤维角分布。尽管该模型的理论基础是发育，但它仅需要成熟状态的几何形状，因此在基于临床成像获取椎间盘几何形状的患者特定有限元分析中具有实际意义。
