Institute of Experimental Mechanics, Faculty of Civil Engineering, Leipzig University of Applied Sciences, Karl-Liebknecht-Str. 132, 04277, Leipzig, Germany; Institute of Anatomy, Faculty of Medicine, Leipzig University, Liebigstr. 13, 04103, Leipzig, Germany.
Institute of Experimental Mechanics, Faculty of Civil Engineering, Leipzig University of Applied Sciences, Karl-Liebknecht-Str. 132, 04277, Leipzig, Germany.
J Mech Behav Biomed Mater. 2024 Apr;152:106432. doi: 10.1016/j.jmbbm.2024.106432. Epub 2024 Feb 2.
Various studies have shown that the water content affects the elastic behavior of cortical bone. However, there is disagreement regarding the reversibility of the elastic behavior with rewetting. This study investigates this issue using an intrinsic approach, i.e., moisture manipulation and material testing were always carried out on the same specimen. The test results were then evaluated separately for each of several specimens. In total, 24 specimens of human cortical bone from the ischiopubic ramus were examined. The water content was varied in 11 steps, and the corresponding elastic moduli were determined using three-point bending tests within the elastic range. Moisture adjustment was achieved mainly using desiccators, accelerated by forced convection. Reference samples stored in the same manner were evaluated microscopically. The experiments confirmed the known correlation between water content reduction and stiffness increase of cortical bone. Complete drying increased the elastic modulus by about 83 %. By rewetting, the stiffness was significantly reduced again, though not only to the initial state, but even about 24 % below this. Thus, an irreversible alteration of the elastic behavior was observed. Decay of the reference samples was not observed. Therefore, decay is not the main reason for the significant loss of stiffness. In terms of the storage conditions for cortical bone specimens, an environment with 100 % relative humidity yielded the best match with the initial state. This storage method can therefore be recommended for biomechanical specimens used to determine in-vivo-like material parameters.
多项研究表明，水含量会影响皮质骨的弹性行为。然而，关于再润湿时弹性行为的可逆性，存在争议。本研究采用内在方法对此问题进行了研究，即水分处理和材料测试始终在同一标本上进行。然后，分别对多个标本的测试结果进行了评估。总共检查了 24 个人体皮质骨坐骨耻骨支样本。水分含量在 11 个步骤中变化，使用三点弯曲试验在弹性范围内确定相应的弹性模量。水分调节主要通过干燥剂进行，通过强制对流加速。以相同方式储存的参考样本进行了微观评估。实验证实了皮质骨中水分减少与刚度增加之间的已知相关性。完全干燥会使弹性模量增加约 83%。通过再润湿，刚度又显著降低，尽管不仅恢复到初始状态，甚至比初始状态低约 24%。因此，观察到弹性行为的不可逆变化。未观察到参考样本的衰减。因此，衰减不是刚度显著损失的主要原因。就皮质骨标本的储存条件而言，相对湿度为 100%的环境与初始状态最匹配。因此，这种储存方法可以推荐用于确定类似体内材料参数的生物力学标本。
