Yadav Priti, Shefelbine Sandra J, Gutierrez-Farewik Elena M
KTH Engineering Sciences, Mechanics, Royal Institute of Technology, Stockholm, Sweden; KTH BioMEx Center, Royal Institute of Technology, Stockholm, Sweden.
Department of Mechanical and Industrial Engineering, Northeastern University, Boston, USA.
J Biomech. 2016 Jun 14;49(9):1613-1619. doi: 10.1016/j.jbiomech.2016.03.039. Epub 2016 Mar 31.
Mechanical stimuli play a significant role in the process of endochondral growth. Thus far, approaches to understand the endochondral mechanical growth rate have been limited to the use of approximated location and geometry of the growth plate. Furthermore, growth has been simulated based on the average deflection of the growth plate or of the femoral neck. It has also been reported in the literature that the growth plate lies parallel to one of the principal stresses acting on it, to reduce the shear between epiphysis and diaphysis. Hence the current study objectives were (1) to evaluate the significance of a subject-specific finite element model of the femur and growth plate compared to a simplified growth plate model and (2) to explore the different growth direction models to better understand proximal femoral growth mechanisms. A subject-specific finite element model of an able-bodied 7-year old child was developed. The muscle forces and hip contact force were computed for one gait cycle and applied to a finite element model to determine the specific growth rate. Proximal femoral growth was simulated for two different growth direction models: femoral neck deflection direction and principal stress direction. The principal stress direction model captured the expected tendency for decreasing the neck shaft angle and femoral anteversion for both growth plate models. The results of this study suggest that the subject-specific geometry and consideration of the principal stress direction as growth direction may be a more realistic approach for correct prediction of proximal femoral growth morphology.
机械刺激在软骨内生长过程中起着重要作用。到目前为止，了解软骨内机械生长速率的方法仅限于使用生长板的近似位置和几何形状。此外，生长是基于生长板或股骨颈的平均挠度进行模拟的。文献中还报道，生长板与作用于其上的主应力之一平行，以减少骨骺和骨干之间的剪切力。因此，当前的研究目标是：（1）评估与简化的生长板模型相比，特定个体的股骨和生长板有限元模型的重要性；（2）探索不同的生长方向模型，以更好地理解股骨近端的生长机制。建立了一个7岁健康儿童的特定个体有限元模型。计算了一个步态周期的肌肉力和髋关节接触力，并将其应用于有限元模型以确定特定生长速率。针对两种不同的生长方向模型模拟了股骨近端生长：股骨颈偏斜方向和主应力方向。主应力方向模型捕捉到了两种生长板模型中颈干角减小和股骨前倾角减小的预期趋势。本研究结果表明，特定个体的几何形状以及将主应力方向作为生长方向来考虑，可能是正确预测股骨近端生长形态的更现实方法。
