Subrupture tendon fatigue damage.
Subrupture tendon fatigue damage.
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DOI：
10.1002/jor.20722
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发表时间：
2009-02
期刊：
影响因子：
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通讯作者：
Flatow EL
中科院分区：
文献类型：
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作者：
Fung DT;Wang VM;Laudier DM;Shine JH;Basta-Pljakic J;Jepsen KJ;Schaffler MB;Flatow EL
肌腱疲劳的力学和微观结构基础，损伤积累和退化的贡献，知之甚少。为了研究肌腱疲劳过程，对大鼠趾长屈肌腱施加循环载荷（1-16 N），直至达到三个疲劳损伤水平之一，定义为代表疲劳寿命关键区间的峰值夹钳-夹钳应变量：i）低（6.0%-7.0%）; ii）中等（8.5%-9.5%）;和iii）高（11.0%-12.0%）。在疲劳加载之前和之后以及在卸载恢复期之后，诊断性地评估刚度、滞后和夹钳-夹钳应变（通过1-8 N的循环加载），以确定作为损伤测量的机械参数。结果表明，肌腱夹间应变从疲劳加载前到疲劳加载后显著增加，并随着疲劳损伤水平的增加而逐渐增加（p≤0.010）。相反，刚度和滞后变化仅在高疲劳水平下显著（p≤0.043）。相关的显微组织分析表明，低水平的疲劳的特点是孤立的，横向图案的扭结纤维变形。在较高的疲劳水平，肌腱表现出纤维分离和局部断裂的纤维。组织形态计量学分析显示，损伤面积分数随疲劳水平显著增加（p≤0.048）。目前的研究结果的特点是连续的，微观结构的事件，肌腱疲劳过程的基础，并表明，肌腱变形可以用来准确地评估肌腱损伤累积的进展。
The mechanical and microstructural bases of tendon fatigue, by which damage accumulates and contributes to degradation, are poorly understood. To investigate the tendon fatigue process, rat flexor digitorum longus tendons were cyclically loaded (1–16 N) until reaching one of three levels of fatigue damage, defined as peak clamp-to-clamp strain magnitudes representing key intervals in the fatigue life: i) Low (6.0%–7.0%); ii) Moderate (8.5%–9.5%); and iii) High (11.0%–12.0%). Stiffness, hysteresis, and clamp-to-clamp strain were assessed diagnostically (by cyclic loading at 1–8 N) before and after fatigue loading and following an unloaded recovery period to identify mechanical parameters as measures of damage. Results showed that tendon clamp-to-clamp strain increased from pre- to post-fatigue loading significantly and progressively with the fatigue damage level (p≤0.010). In contrast, changes in both stiffness and hysteresis were significant only at the High fatigue level (p≤0.043). Correlative microstructural analyses showed that Low level of fatigue was characterized by isolated, transverse patterns of kinked fiber deformations. At higher fatigue levels, tendons exhibited fiber dissociation and localized ruptures of the fibers. Histomorphometric analysis showed that damage area fraction increased significantly with fatigue level (p≤0.048). The current findings characterized the sequential, microstructural events that underlie the tendon fatigue process and indicate that tendon deformation can be used to accurately assess the progression of damage accumulation in tendons.