Tissue Mechanics Laboratory, Biomedical Engineering Department, Sahand University of Technology, PO. BOX 51335-1996, Tabriz, Iran.
Tissue Mechanics Laboratory, Biomedical Engineering Department, Sahand University of Technology, PO. BOX 51335-1996, Tabriz, Iran.
Med Eng Phys. 2020 Apr;78:48-54. doi: 10.1016/j.medengphy.2020.01.010. Epub 2020 Feb 6.
The interface between the Achilles Tendon (AT) and calcaneus comprises soft and hard connective tissues. Such interfaces are vulnerable to mechanical damage. Tendon to Bone Insertion Region (TBIR) has unique microstructural characteristics for reinforcement. This region constitutes almost 10% of the AT's distal end. The rest of the tendon (tendon proper) has longitudinal fiber orientation with no mineral content. Although, the TBIR lacks longitudinally organized fibers and at the same time, incorporates mineral molecules. In this study, a 3D computational model of the TBIR proposed to underline several reinforcement mechanisms. The obtained results showed that off-axis alignment of fibers, when coupled with the mineral deposition, shifts the stress concentration region to the tendon proper. In the case of altering each parameter individually, probable failure observed in the bone interface, which causes complications in surgical procedure or during healing. A gradual increase of mineral compensates for the stiffness mismatch between the AT and calcaneus. The proposed computational framework illustrated the complementary roles of fiber orientation and mineral molecules: nearly transverse orientation of fibers alleviated the stress concentration locally, while mineral deposition directly enhanced the TBIR stiffness.
跟腱（AT）和跟骨之间的界面由软、硬连接组织组成。这种界面容易受到机械损伤。肌腱骨插入区（TBIR）具有独特的微观结构特征，可起到增强作用。该区域构成 AT 远端的近 10%。其余的肌腱（肌腱本身）具有纵向纤维取向，没有矿物质含量。尽管如此，TBIR 缺乏纵向组织的纤维，同时又包含矿物质分子。在这项研究中，提出了一个 TBIR 的三维计算模型，以强调几种增强机制。所得结果表明，当纤维的偏轴对准与矿物质沉积结合时，会将应力集中区域转移到肌腱本身。在单独改变每个参数的情况下，在骨界面观察到可能的失效，这会导致手术过程或愈合期间出现并发症。矿物质的逐渐增加补偿了 AT 和跟骨之间的刚度不匹配。所提出的计算框架说明了纤维取向和矿物质分子的互补作用：纤维的近乎横向取向局部缓解了应力集中，而矿物质沉积则直接增强了 TBIR 的刚度。
