Sham M L, Zander T, Rohlmann A, Bergmann G
Biomechanics Laboratory, Department of Orthopaedics, Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, Berlin 12203.
Biomed Tech (Berl). 2005 Nov;50(11):361-5. doi: 10.1515/BMT.2005.051.
Besides protecting the internal organs of the thorax, the rib cage is the site of numerous muscle attachments. It also decreases the overall flexibility of the thoracic spine. This study developed finite element (FE) models of the thoracic spine with and without the rib cage, and the effects of the rib cage on thoracic spine flexibility were determined. The numerical models were validated by comparing the maximum rotation of the models for several loading cases with experimental data in the literature. After adapting the material properties for the discs and ligaments, the calculated maximum rotations differed from the measured median values by less than 1 degrees without the rib cage and by less than 2.5 degrees with it. The rib cage decreased the mean flexibility of the thoracic spine by 23% to 47%, depending on the loading plane. Assuming the ribs to be rigid beams required a corresponding reduction of ligament stiffnesses in order to achieve the same agreement of the maximum rotations with the measured median values. Interconnecting the FE thoracic spine model plus rib cage with the existing detailed FE lumbar spine model improves the simulation of force directions of muscles attached to the rib cage or thoracolumbar spine. In addition, such a model is suitable for determining the effects of lumbar spine implants on spinal balance.
除了保护胸部的内部器官外，胸廓还是众多肌肉附着的部位。它还会降低胸椎的整体灵活性。本研究建立了有胸廓和无胸廓的胸椎有限元（FE）模型，并确定了胸廓对胸椎灵活性的影响。通过将几种加载情况下模型的最大旋转角度与文献中的实验数据进行比较，对数值模型进行了验证。在调整椎间盘和韧带的材料属性后，无胸廓时计算出的最大旋转角度与测量的中值相差不到1度，有胸廓时相差不到2.5度。根据加载平面的不同，胸廓使胸椎的平均灵活性降低了23%至47%。假设肋骨为刚性梁，则需要相应降低韧带刚度，以便使最大旋转角度与测量的中值达到相同的一致性。将有限元胸椎模型加胸廓与现有的详细有限元腰椎模型相连，可改善对附着于胸廓或胸腰椎的肌肉力方向的模拟。此外，这样的模型适用于确定腰椎植入物对脊柱平衡的影响。
