Rizza Robert, Liu Xuecheng
Department of Mechanical Engineering, Milwaukee School of Engineering, Milwaukee, WI 53202, USA.
J Biomech Eng. 2013 Aug;135(8):81003. doi: 10.1115/1.4024628.
Axial loading of vertebral bodies has been shown to modulate growth. Longitudinal growth of the vertebral body is impaired by compressive forces while growth is stimulated by distraction. Investigations of torsional loading on the growth plate in the literature are few. The purposes of this study were two-fold: (1) to develop a torque device to apply torsional loads on caudal vertebrae and (2) investigate numerically and in vivo the feasibility of the application of the torque on the growth plate. A controllable torque device was developed and validated in the laboratory. A finite element study was implemented to examine mechanically the deformation of the growth plate and disk. A rat tail model was used with six 5-week-old male Sprague-Dawley rats. Three rats received a static torsional load, and three rats received no torque and served as sham control rats. A histological study was undertaken to investigate possible morphological changes in the growth plate, disk, and caudal bone. The device successfully applied a controlled torsional load to the caudal vertebrae. The limited study using finite element analysis (FEA) and histology demonstrated that applied torque increased lateral disk height and increased disk width. The study also found that the growth plate height increased, and the width decreased as well as a curved displacement of the growth plate. No significant changes were observed from the in vivo study in the bone. The torsional device does apply controlled torque and is well tolerated by the animal. This study with limited samples appears to result in morphological changes in the growth plate and disk. The use of this device to further investigate changes in the disk and growth plate is feasible.
已证明椎体的轴向负荷可调节生长。压缩力会损害椎体的纵向生长，而牵张则会刺激生长。文献中对生长板扭转负荷的研究很少。本研究有两个目的：（1）开发一种扭矩装置，以对尾椎施加扭转载荷；（2）在数值上和体内研究对生长板施加扭矩的可行性。在实验室中开发并验证了一种可控扭矩装置。进行了有限元研究，以机械方式检查生长板和椎间盘的变形情况。使用大鼠尾巴模型，选用六只5周龄的雄性Sprague-Dawley大鼠。三只大鼠接受静态扭转载荷，三只大鼠不接受扭矩，作为假对照大鼠。进行了组织学研究，以调查生长板、椎间盘和尾骨可能出现的形态变化。该装置成功地对尾椎施加了可控的扭转载荷。使用有限元分析（FEA）和组织学进行的有限研究表明，施加扭矩会增加椎间盘的外侧高度并增加椎间盘宽度。研究还发现，生长板高度增加，宽度减小，并且生长板出现弯曲位移。在体内研究中未观察到骨骼有明显变化。该扭转装置确实能施加可控扭矩，并且动物耐受性良好。这项样本有限的研究似乎导致了生长板和椎间盘的形态变化。使用该装置进一步研究椎间盘和生长板的变化是可行的。
