Institute of Orthopaedic Research and Biomechanics, Trauma Research Centre Ulm, Ulm University, Ulm, Germany.
Institute of Orthopaedic Research and Biomechanics, Trauma Research Centre Ulm, Ulm University, Ulm, Germany; SpineServ GmbH & Co. KG, Ulm, Germany.
J Biomech. 2019 Sep 20;94:147-157. doi: 10.1016/j.jbiomech.2019.07.041. Epub 2019 Aug 7.
Neither kinematic nor stiffness properties of the rib cage during thoracic spinal motion were investigated in previous studies, while being essential for the accurate validation of numerical models of the whole thorax. The aim of this in vitro study therefore was to quantify the kinematics and elastostatics of the human rib cage under defined boundary conditions. Eight fresh frozen human thoracic spine specimens (C7-L1, median age 55 years, ranging from 40 to 60 years) including entire rib cages were loaded quasi-statically in flexion/extension, lateral bending, and axial rotation using pure moments of 5Nm. Relative motions of ribs, thoracic vertebrae, and sternal structures as well as strains on the ribs were measured using optical motion tracking of 150 reflective markers per specimen, while specimens were loaded displacement-controlled with a constant rate of 1°/s for 3.5 cycles. The third full cycle was used to determine relative angles and strains at full loading of the spine for all motion directions. Largest relative angles were found in the main loading directions with only small motions at the mid-thoracic levels. Highest strains of the intercostal spaces were detected in the anterior section of the lowest fourth of the rib cage, showing compressions and elongations of more than 10% in all spinal motion planes. Elastostatic rib deformation was generally less than 1%. Rib-sternum relative motions exhibited complex motion patterns, overall showing relative angles below 2°. The results indicate that rib cage structures are not macroscopically deformed during spinal motion, but exhibit characteristic reproducible kinematics patterns.
在先前的研究中，没有研究过胸廓脊柱运动过程中胸廓的运动学或刚度特性，而这些特性对于整个胸廓的数值模型的准确验证是至关重要的。因此，本体外研究的目的是定量研究在定义的边界条件下，人类胸廓的运动学和弹性静力学。 本研究使用 5Nm 的纯力矩对 8 个新鲜冷冻的人类胸脊柱标本（C7-L1，中位年龄 55 岁，范围为 40-60 岁）进行了准静态加载，包括整个胸廓。使用每个标本 150 个反光标记的光学运动跟踪测量了肋骨、胸椎和胸骨结构的相对运动以及肋骨的应变，同时以 1°/s 的恒定速率对标本进行加载 3.5 个循环。第三个完整循环用于确定所有运动方向的脊柱完全加载时的相对角度和应变。在主要加载方向上发现了最大的相对角度，而在中胸水平上只有很小的运动。在肋骨笼最低四分之一的前部分，检测到肋间隙的最高应变，在所有脊柱运动平面上都有超过 10%的压缩和伸长。弹性肋骨变形通常小于 1%。肋骨-胸骨相对运动表现出复杂的运动模式，整体显示相对角度低于 2°。结果表明，胸廓结构在脊柱运动过程中不会发生宏观变形，而是表现出特征性的可重复运动模式。
