Magnitude of loads influences the site of failure of highly curved bones.
Magnitude of loads influences the site of failure of highly curved bones.
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载荷的大小影响高度弯曲的骨头的失效部位。
DOI：
10.1016/j.jmbbm.2013.11.018
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发表时间：
2014
影响因子：
3.9
通讯作者：
Kotha,Shiva
中科院分区：
文献类型：
--
作者：
Macione,James;Nesbitt,RobertSterling;Kotha,Shiva
骨的结构和材料特性沿着应用的边界条件确定了峰值应力的区域，在该区域预期发生骨折。由于峰值应力的位置不受施加载荷大小的影响，因此在不同载荷下对全骨进行疲劳加载期间，预计骨折部位不会发生变化。然而，在一个高度弯曲的骨，如大鼠尺骨，施加的负载的大小被发现影响骨折部位。在载荷控制下对完整的大鼠前臂和切除的尺骨进行疲劳载荷。确定尺骨鹰嘴近端至骨折部位的距离。在完整前臂中，失效部位表现出向远端线性进展，朝向具有较低惯性矩的部位（或表现出较低截面模量的部位）。在低载荷下加载至失效的完整大鼠前臂和切除的尺骨在施加高载荷时失效处远端2-3 mm处断裂。这表明，仅通过改变施加的载荷大小，就可使失效部位移位约10%的整个骨长度。当以2 Hz或4 Hz加载时，切除尺骨的失效部位相似，这表明在此范围内与频率无关，并表明应变率不是重要的影响因素。蠕变加载切除尺骨也表现出类似的变化，在网站的失败，表明负载的大小，而不是类型的负载是重要的，在确定网站的失败。这对于在生理负荷下发生损伤的骨体积具有重要意义。
The structure and material properties of bones along with applied boundary conditions determine the region of peak stresses, where fracture is expected to occur. As the site of peak stresses is not influenced by the magnitude of applied load, the fracture site is not expected to change during fatigue loading of whole bone at different loads. However, in a highly curved bone such as the rat ulna, the magnitude of applied loads was found to influence the fracture site. Fatigue loading was conducted under load control on intact rat forearms and on excised ulnae. The distance to the site of failure from the proximal olecranon process of ulnae was determined. In intact forearms, the site of failure demonstrated a linear progression distally, towards sites with lower moment of inertia (or sites exhibiting lower section modulus). Intact rat forearms and excised ulnae loaded to failure at low loads fractured 2–3 mm distal to where they failed when applying high loads. This indicates a shift in the site of failure by approximately 10% of whole bone length just by varying the applied load magnitude. The site of failure in excised ulnae was similar when loading at 2 Hz or at 4 Hz, suggesting that this was frequency independent in this range and indicating that strain rate was not an important contributing factor. Creep loading of excised ulnae also demonstrated similar changes in the site of failure, indicating that magnitude of loads, and not type of loading were important in determining the site of failure. This has important implications with regards to the volume of bone that undergoes damage under physiological loading, before it fails.