Department of Mechanical and Management Engineering (DIMeG), Politecnico di Bari, Italy.
J Biomech. 2010 Jan 19;43(2):334-42. doi: 10.1016/j.jbiomech.2009.07.042. Epub 2009 Nov 11.
Clinical studies have recently documented that there is sufficient evidence to suggest that abnormal motion may be an indicator of abnormal mechanics of the spine and, therefore, may be associated with some types of low-back pain. However, designating a motion as abnormal requires knowledge of normal motions. This work hence aims to develop an accurate computational model to simulate the bio-mechanical response of the whole lumbosacral spinal unit (L1-S1) under physiological loadings and constraint conditions. In order to meet this objective, computed tomography (CT) scanning protocols, finite element (FE) analysis and accurate constitutive modelling have been integrated. Then the ranges of motion (ROM) under flexion, extension and lateral bending moment were measured and compared with experimental data, finding an excellent agreement. In particular, the ability of the model to reproduce the relative rotation between each couple of vertebrae was proved. Finally, the shear stresses for the most extreme load cases were reported in order to predict which are the most risky conditions and where the maximum damage would be located. The results indicate that the greater values of the stresses were located at L4-S1 levels just in the interfaces between disc and vertebrae across the posterior and posterolateral zone. This result can be clinically correlated with the existence of damage exactly where the stresses were maximal in the proposed finite element model.
临床研究最近记录表明，有充分的证据表明异常运动可能是脊柱力学异常的指标，因此可能与某些类型的下腰痛有关。然而，指定一个运动为异常需要了解正常运动。因此，这项工作旨在开发一个准确的计算模型，以模拟生理负荷和约束条件下整个腰骶部脊柱单元（L1-S1）的生物力学响应。为了实现这一目标，整合了计算机断层扫描（CT）扫描方案、有限元（FE）分析和精确的本构模型。然后测量了屈伸和侧屈时的运动范围（ROM），并与实验数据进行了比较，发现吻合得非常好。特别是，该模型再现每个椎体对之间相对旋转的能力得到了证明。最后，报告了最极端载荷情况下的剪切应力，以预测哪些是最危险的情况，以及最大的损伤将位于何处。结果表明，最大的应力值位于 L4-S1 水平，正好在椎间盘和椎体之间的后区和后外侧区的交界处。这一结果可以与在提出的有限元模型中应力最大的部位存在损伤的临床相关性进行比较。
