Development of artificial intervertebral disc and artificial nucleus pulposus

(1)人L4-5功能单元在循环载荷作用下的力学性能评价：对10个新鲜的人L4-5功能单元进行循环轴向拉伸试验和循环扭转试验，以考察L4-5功能单元后部单元的结构效应，在每个载荷下，功能单元的刚度随着位移的增加而增加，在完整的功能单元和去除每个后部单元后的功能单元中的情况是相同的。L4-5功能脊椎单位的压缩、拉伸和扭转僵硬是由后方的所有成分决定的。关节突关节对椎体的压缩和扭转刚度有显著影响。关节突关节对扭转刚度的影响随位移量的增加而增大，而对压缩刚度的影响不变。后韧带(S…(2)人体L4-5椎间盘在循环载荷作用下的力学性能评价：10个新鲜的人体L4-5椎体单元(DBU)通过循环压缩-拉伸和扭转试验，研究L4-5椎间盘的刚度特性与位移的关系。研究了纤维环损伤、髓核摘除及硅橡胶填充脱核间隙对L4-5椎体刚度特性的影响。L4-5椎间盘在各种载荷作用下，随着位移的增加，其刚度增加，在每种载荷作用下，髓核摘除后腰椎间盘各移位区域的刚度均显著降低。用硅橡胶填充去核间隙后，扭转刚度明显恢复。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，以重建人类功能脊柱单位的稳定性和活动度。通过三维有限元计算机仿真设计了人工腰椎间盘的几何和结构，该模型的压缩和扭转刚度与身体腰椎间盘的刚度一致，因此，该模型由两个生物活性陶瓷板和橡胶类材料制成的中间子结构组成。含有磷灰石和硅灰石的微晶玻璃被选为与骨接触的平板材料，因为这种材料能够与骨组织形成强烈的化学结合。在两个钢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身体腰椎间盘相同的刚度特性。较少

(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