Pardes A M, Freedman B R, Fryhofer G W, Salka N S, Bhatt P R, Soslowsky L J
McKay Orthopaedic Laboratory, University of Pennsylvania, 424 Stemmler Hall, 3450 Hamilton Walk, Philadelphia, PA, 19104-6081, USA.
Ann Biomed Eng. 2016 Oct;44(10):2901-2910. doi: 10.1007/s10439-016-1635-1. Epub 2016 May 5.
The Achilles tendon is the most commonly ruptured tendon in the human body. Numerous studies have reported incidence of these injuries to be upwards of five times as common in men than women. Therefore, the objective of this study was to investigate the sex- and hormone-specific differences between Achilles tendon and muscle between female, ovariectomized female (ovarian hormone deficient), and male rats. Uninjured tissues were collected from all groups for mechanical, structural, and histological analysis. Our results showed that while cross-sectional area and failure load were increased in male tendons, female tendons exhibited superior tendon material properties and decreased muscle fiber size. Specifically, linear and dynamic moduli were increased while viscoelastic properties (e.g., hysteresis, percent relaxation) were decreased in female tendons, suggesting greater resistance to deformation under load and more efficient energy transfer, respectively. No differences were identified in tendon organization, cell shape, cellularity, or proteoglycan content. Additionally, no differences in muscle fiber type distribution were observed between groups. In conclusion, inferior tendon mechanical properties and increased muscle fiber size may explain the increased susceptibility for Achilles tendon injury observed clinically in men compared to women.
跟腱是人体最常发生断裂的肌腱。众多研究报告称，这些损伤的发生率在男性中比女性高出五倍以上。因此，本研究的目的是调查雌性、去卵巢雌性（卵巢激素缺乏）和雄性大鼠跟腱与肌肉之间的性别及激素特异性差异。从所有组中收集未受伤组织进行力学、结构和组织学分析。我们的结果表明，虽然雄性肌腱的横截面积和破坏负荷增加，但雌性肌腱表现出更好的肌腱材料特性且肌纤维尺寸减小。具体而言，雌性肌腱的线性模量和动态模量增加，而粘弹性特性（如滞后、松弛百分比）降低，分别表明在负荷下对变形的抵抗力更强和能量传递更有效。在肌腱组织结构、细胞形状、细胞密度或蛋白聚糖含量方面未发现差异。此外，各组之间未观察到肌纤维类型分布的差异。总之，较差的肌腱力学性能和增加的肌纤维尺寸可能解释了临床上观察到的男性跟腱损伤易感性高于女性的现象。
