PDF(Pubmed)
Abstract：
Background: The treatment of patellar tendon injury has always been an unsolved problem, and mechanical characterization is very important for its repair and reconstruction. Elastin is a contributor to mechanics, but it is not clear how it affects the elasticity, viscoelastic properties, and structure of patellar tendon. Methods: The patellar tendons from six fresh adult experimental pigs were used in this study and they were made into 77 samples. The patellar tendon was specifically degraded by elastase, and the regional mechanical response and structural changes were investigated by: (1) Based on the previous study of elastase treatment conditions, the biochemical quantification of collagen, glycosaminoglycan and total protein was carried out; (2) The patellar tendon was divided into the proximal, central, and distal regions, and then the axial tensile test and stress relaxation test were performed before and after phosphate-buffered saline (PBS) or elastase treatment; (3) The dynamic constitutive model was established by the obtained mechanical data; (4) The structural relationship between elastin and collagen fibers was analyzed by two-photon microscopy and histology. Results: There was no statistical difference in mechanics between patellar tendon regions. Compared with those before elastase treatment, the low tensile modulus decreased by 75%-80%, the high tensile modulus decreased by 38%-47%, and the transition strain was prolonged after treatment. For viscoelastic behavior, the stress relaxation increased, the initial slope increased by 55%, the saturation slope increased by 44%, and the transition time increased by 25% after enzyme treatment. Elastin degradation made the collagen fibers of patellar tendon become disordered and looser, and the fiber wavelength increased significantly. Conclusion: The results of this study show that elastin plays an important role in the mechanical properties and fiber structure stability of patellar tendon, which supplements the structure-function relationship information of patellar tendon. The established constitutive model is of great significance to the prediction, repair and replacement of patellar tendon injury. In addition, human patellar tendon has a higher elastin content, so the results of this study can provide supporting information on the natural properties of tendon elastin degradation and guide the development of artificial patellar tendon biomaterials.
摘要：
背景:髌腱损伤的治疗一直是一个尚未解决的问题,力学表征对其修复和重建非常重要。Elastin是力学的贡献者，但不清楚它如何影响弹性，粘弹性，髌腱结构。方法：本研究使用6只新鲜成年实验猪的髌腱，将其制成77份样品。髌腱被弹性蛋白酶特异性降解，并通过以下方法对区域力学响应和结构变化进行了研究:(1)在前人对弹性蛋白酶处理条件研究的基础上,胶原蛋白的生化定量，进行了糖胺聚糖和总蛋白的测定；（2）髌腱分为近端，中央,和远端区域，然后在磷酸盐缓冲盐水(PBS)或弹性蛋白酶处理前后进行轴向拉伸试验和应力松弛试验;(3)根据获得的力学数据建立动态本构模型;(4)通过双光子显微镜和组织学分析弹性蛋白与胶原纤维的结构关系。结果：髌腱区域之间的力学没有统计学差异。与弹性蛋白酶治疗前相比，低拉伸模量降低了75%-80%，高拉伸模量下降了38%-47%，治疗后过渡应变延长。对于粘弹性行为，应力松弛增加，初始坡度增加了55%，饱和斜率增加了44%，酶处理后过渡时间增加了25%。弹性蛋白的降解使髌腱的胶原纤维变得无序和松散，光纤波长显著增加。结论:本研究结果表明,弹性蛋白在髌腱的力学性能和纤维结构稳定性中起着重要作用,补充髌腱的结构-功能关系信息。所建立的本构模型对预测具有重要意义,髌腱损伤的修复和置换。此外,人髌腱具有较高的弹性蛋白含量，因此，本研究结果可为肌腱弹性蛋白降解的自然特性提供支持信息，指导人工髌腱生物材料的开发。
