Miller Kristin S, Connizzo Brianne K, Feeney Elizabeth, Tucker Jennica J, Soslowsky Louis J
McKay Orthopaedic Research Laboratory, University of Pennsylvania, 424 Stemmler Hall, 36th and Hamilton Walk, Philadelphia, PA 19104-6081, USA.
J Biomech Eng. 2012 Apr;134(4):041004. doi: 10.1115/1.4006538.
Crimp morphology is believed to be related to tendon mechanical behavior. While crimp has been extensively studied at slack or nondescript load conditions in tendon, few studies have examined crimp at specific, quantifiable loading conditions. Additionally, the effect of the number of cycles of preconditioning on collagen fiber crimp behavior has not been examined. Further, the dependence of collagen fiber crimp behavior on location and developmental age has not been examined in the supraspinatus tendon. Local collagen fiber crimp frequency is quantified throughout tensile mechanical testing using a flash freezing method immediately following the designated loading protocol. Samples are analyzed quantitatively using custom software and semi-quantitatively using a previously established method to validate the quantitative software. Local collagen fiber crimp frequency values are compared throughout the mechanical test to determine where collagen fiber frequency changed. Additionally, the effect of the number of preconditioning cycles is examined compared to the preload and toe-region frequencies to determine if increasing the number of preconditioning cycles affects crimp behavior. Changes in crimp frequency with age and location are also examined. Decreases in collagen fiber crimp frequency were found at the toe-region at all ages. Significant differences in collagen fiber crimp frequency were found between the preload and after preconditioning points at 28 days. No changes in collagen fiber crimp frequency were found between locations or between 10 and 28 days old. Local collagen fiber crimp frequency throughout mechanical testing in a postnatal developmental mouse SST model was measured. Results confirmed that the uncrimping of collagen fibers occurs primarily in the toe-region and may contribute to the tendon's nonlinear behavior. Additionally, results identified changes in collagen fiber crimp frequency with an increasing number of preconditioning cycles at 28 days, which may have implications on the measurement of mechanical properties and identifying a proper reference configuration.
人们认为卷曲形态与肌腱的力学行为有关。虽然已经在肌腱松弛或无特定负荷条件下对卷曲进行了广泛研究，但很少有研究在特定的、可量化的负荷条件下研究卷曲。此外，预处理循环次数对胶原纤维卷曲行为的影响尚未得到研究。此外，在冈上肌腱中，胶原纤维卷曲行为对位置和发育年龄的依赖性也未得到研究。在按照指定加载方案进行拉伸力学测试后，立即使用快速冷冻方法在整个测试过程中对局部胶原纤维卷曲频率进行量化。使用定制软件对样品进行定量分析，并使用先前建立的方法进行半定量分析，以验证定量软件。在整个力学测试过程中比较局部胶原纤维卷曲频率值，以确定胶原纤维频率发生变化的位置。此外，将预处理循环次数的影响与预加载和趾区频率进行比较，以确定增加预处理循环次数是否会影响卷曲行为。还研究了卷曲频率随年龄和位置的变化。在所有年龄组的趾区均发现胶原纤维卷曲频率降低。在28天时，预加载点和预处理后点之间的胶原纤维卷曲频率存在显著差异。在不同位置之间或10至28日龄之间未发现胶原纤维卷曲频率的变化。测量了出生后发育小鼠冈上肌腱模型在整个力学测试过程中的局部胶原纤维卷曲频率。结果证实，胶原纤维的展开主要发生在趾区，可能是肌腱非线性行为的原因。此外，结果还确定了在28天时，随着预处理循环次数的增加，胶原纤维卷曲频率发生变化，这可能对力学性能的测量和确定合适的参考构型有影响。
