Development of artificial intervertebral disc and artificial nucleus pulposus

(1)在循环载荷过程中，人体L4-5功能性脊柱单元的力学性能评价：对10个新鲜人L4-5功能性脊柱单元进行了循环轴向压缩-拉伸试验和循环扭转试验，研究了L4-5功能性脊柱单元后部结构的结构效应，结果表明，在每种载荷下，功能性脊柱单元的刚度随位移的增加而增加，这在完整的功能性脊柱单元和去除每个后部元件后的功能性脊柱单元中分别是相同的。所有后部元件均对L4-5功能性脊柱单元的压缩、拉伸和扭转刚度有贡献。骨突关节对压缩和扭转刚度有显著影响。骨突关节对扭转刚度的影响随位移的增大而增大，而对压缩刚度的影响则保持不变。后韧带 关于我们 棘上韧带和棘间韧带）对拉伸刚度有显著影响。(2)人体L4-5椎间盘在循环载荷下的力学性能评价：对10个新鲜人体L4-5椎间盘体单元（DBU）进行了检查，以通过循环压缩-拉伸和扭转试验来研究L4-5椎间盘的刚度特性与位移之间的关系。纤维环损伤、髓核摘除和硅橡胶填充对L4-5椎间盘刚度的影响表明，在各种载荷下，L4 -5椎间盘刚度均随位移的增加而增加，髓核摘除后椎间盘刚度在各位移区均显著降低。通过用硅橡胶填充去核间隙，扭转刚度显著恢复。然而，压缩和拉伸刚度几乎没有恢复。(3)人工椎间盘的结构设计：提出了一种新的人工椎间盘，以重建人体功能脊柱单元的稳定性和活动性。利用三维有限元法对人工椎间盘的几何形状和结构进行了计算机模拟，该模型的压缩和扭转刚度与尸体腰椎间盘的刚度一致，因此，该模型由两块生物活性陶瓷板和由橡胶类材料制成的中间子结构组成。选择含有磷灰石和硅灰石的玻璃陶瓷作为与骨接触的接骨板的材料，因为这种材料能够与骨组织形成牢固的化学键。在两个板之间的子结构中选择医用级弹性材料，因为人工椎间盘具有与尸体腰椎间盘相同的刚度特性。少

(1) Evaluation of the mechanical properties of the human L4-5 functional spinal unit during cyclic loading : Cyclic axial compression-tension tests and cyclic torsional tests were performed on ten fresh human L4-5 functional spinal units to investigate the structural effects of the posterior elements of L4-5 functional spinal units.The stiffness of the functional spinal unit increased with increase of displacement under every loading, This was same in the intact functional spinal units and the functional spinal units after removal each posterior element, respectively. All the posterior elements contributed to the compressive, tensile, and torsional stiffness of L4-5 functional spinal units. The apophyseal joints had a significant effect on the compressive and torsional stiffness. The effect of the apophyseal joints on the torsional stiffness became greater according to the extent of displacement, whereas their effect on the compressive stiffness was constant. The posterior ligaments (s … More upraspinous and interspinous ligaments) had a significant effect on the tensile stiffness.(2) Evaluation of the mechanical properties of the human L4-5 disc during cyclic loading : Ten fresh human L4-5 disc-body units (DBUs) were examined for investigation of the relationship between the stiffness properties of L4-5 intervertebral disc and the displacement by cyclic compression-tension and torsion tests. The effects of an injury to the anulus fibrosus, nucleotomy and the filling-up of the denucleated space with silicone elastomer on the stiffness properties of L4-5 disc were also investigated.The stiffness of L4-5 intervertebral disc increased with the increase of displacement in every type of loading, In each type of loading, the stiffness of the intervertebral disc after nucleotomy decreased significantly in every region of displacement. The torsional stiffness was restored significantly by the filling-up of the denucleated space with silicone elastomer. However, there was little restoration of both the compressive and tensile stiffness.(3) Structural design of an artificial intervertebral disc : A new artificial intervertebral disc is proposed to reconstruct the stability and mobility of a human functional spinal unit. The geometry and the structure of the artificial intervertebral disc were designed by the computer simulation at 3D-FEM, as the compressive and the torsional stiffness of this model agree with the stiffness of cadaveric lumbar discs.Consequently, the proposed model consists of two bioactive ceramic plates and intervenient substructure made from rubber-like materials. Glass-ceramic containing apatite and wollastonite was chosen as a material for the plates which come into contact with the bone, because this material is able to form a strong chemical bond with the osseous tissue. Elastic materials of medical grade in the substructure between two plates were selected, as a the artificial disc has the same stiffness properties with a cadaveric lumbar disc. Less