Schaffler M B, Radin E L, Burr D B
Department of Anatomy, West Virginia University Health Sciences Center, Morgantown.
Bone. 1989;10(3):207-14. doi: 10.1016/8756-3282(89)90055-0.
Compact bone specimens were cyclically loaded in uniaxial tension for one million cycles; loading was performed at either of two physiological strain rates (0.01 s-1 or 0.03 s-1) and a physiological strain range (0-1200 microstrain). Microdamage in loaded and nonloaded control specimens was then assessed histomorphometrically. Fatigue, evidence by stiffness loss, was observed at both strain rates and was significantly greater in specimens loaded at the high experimental strain rate than in specimens loaded at the low strain rate. Morphologically, this fatigue corresponded to increased numbers of microcracks in the bone. These data show that fatigue and resultant microdamage are realistic expectations of cyclic loading within the physiological strain range. The rate at which strains are developed influences the fatigue behavior of compact bone, suggesting that cyclic loading at high physiological strain rates, characteristic of vigorous activities, is more damaging to compact bone than loading at lower physiological strain rates.
致密骨标本在单轴拉伸下进行了100万次循环加载；加载在两种生理应变率（0.01 s-1或0.03 s-1）之一以及生理应变范围（0 - 1200微应变）下进行。然后通过组织形态计量学评估加载和未加载对照标本中的微损伤。在两种应变率下均观察到疲劳现象，表现为刚度损失，且在高实验应变率下加载的标本中的疲劳程度显著高于低应变率下加载的标本。从形态学上看，这种疲劳对应于骨中微裂纹数量的增加。这些数据表明疲劳和由此产生的微损伤是生理应变范围内循环加载下现实的预期结果。应变产生的速率会影响致密骨疲劳行为，这表明高生理应变率下的循环加载（这是剧烈活动的特征）对致密骨的损害比低生理应变率下加载更大。
