Kamal Saeid, Hashemi Ata
Biomechanical Engineering Group, Biomedical Engineering Department, Amirkabir University of Technology, Tehran, Iran.
Arch Bone Jt Surg. 2020 Nov;8(6):682-688. doi: 10.22038/abjs.2020.45716.2251.
The vertebral column is the second most common fracture site in individuals with high-grade osteoporosis (30-50%). Most of these fractures are caused by falls. This information reveals the importance of considering impact loading conditions of spinal motion segments, while no commercial apparatus is available for this purpose. Therefore, the goal was set to fabricate an impact testing device for the measurement of impact behavior of the biological tissues.
In the present study, first, a drop-weight impact testing apparatus was designed and fabricated to record both force and displacement at a sample rate of 100 kHz. A load cell was placed under the sample, and an accelerometer was located on the impactor. Previous devices have mostly measured the force and not the deformation. Thereafter, the effect of high axial compression load was investigated on a biological sample, i.e., the lumbar motion segment, was investigated. To this end, nine ovine segments subjected to vertical impact load were examined using the fabricated device, and the mechanical properties of the lumbar segments were extracted and later compared with quasi-static loading results.
The results indicated that the specimen stiffness and failure energy in impact loading were higher than those in the quasi-static loading. In terms of the damage site, fracture mainly occurred in the body of the vertebra during impact loading; although, during quasi-static loading, the fracture took place in the endplates.
The present study introduces an inexpensive drop-test device capable of recording both the force and the deformation of the biological specimens when subjected to high-speed impacts. The mechanical properties of the spinal segments have also been extracted and compared with quasi-static loading results.
在患有重度骨质疏松症的个体中，脊柱是第二常见的骨折部位（30%-50%）。这些骨折大多由跌倒引起。这一信息揭示了考虑脊柱运动节段冲击载荷条件的重要性，然而目前尚无用于此目的的商用设备。因此，设定目标是制造一种用于测量生物组织冲击行为的冲击测试装置。
在本研究中，首先设计并制造了一种落锤冲击测试装置，以100kHz的采样率记录力和位移。在样品下方放置一个测力传感器，在冲击器上放置一个加速度计。以往的装置大多测量力而非变形。此后，研究了高轴向压缩载荷对生物样本即腰椎运动节段的影响。为此，使用制造的装置对九个承受垂直冲击载荷的绵羊腰椎节段进行了检查，并提取了腰椎节段的力学性能，随后与准静态加载结果进行比较。
结果表明，冲击加载下的样本刚度和破坏能量高于准静态加载。在损伤部位方面，冲击加载时骨折主要发生在椎体；而在准静态加载时，骨折发生在终板。
本研究介绍了一种廉价的落锤测试装置，能够记录生物样本在高速冲击下的力和变形。还提取了脊柱节段的力学性能并与准静态加载结果进行了比较。
