缺损关节软骨损伤演化力学机制的研究

Osteoarthritis disease is severely harmful to the health and living quality of human being. Its formation is correlated with the damage evolution of articular cartilage. The purpose of the present study of the damage evolution process and the mass transfer process is to reveal the damage evolution mechanism of defective articular cartilage，illustrate mechanics mechanism and determine influence factors. This research will be carry out by experiment and numerical simulation method. Porcine articular cartilage is used as the object of study, the thickness of different layers of cartilage zone is determined according to some dyeing experiments. Comformed with clinical data of articular cartilages, the preparation of defective specimens is done. The sliding load and rolling load are applied on the specimens, respectively. Using Digital image correlation technique, the influence of defective form and load case on the damage evolution process and mass transfer process is studied. Parametric study is applied considering of the defective location, defective shape and depth, compression size and loading rate. Simultaneously, the influence of microstructure on the process of damage evolution and mass transfer is studied including the collagen fiber content, distribution and proteoglycan content. The process of damage evolution and the mass transfer are simulated numerically. The damage evolution model of articular cartilage is established based on mesoscopic damage mechanics theory. The damage evolution law of defective articular cartilage is summarized. Our researches will contribute to predict the results of the damage evolution under complex conditions and cartilage lifetime. Therefore, it has important significance for defect repairment, prevention and treatment of osteoarthritis disease.

骨关节炎严重影响人的健康和生活质量，其形成与关节软骨损伤演化有密切关系。研究缺损软骨的损伤演化过程和传质过程目的在于揭示缺损软骨的损伤演化规律，阐述力学机制和确定影响因素。课题拟通过实验和数值模拟结合的方法开展研究。以猪膝关节软骨为研究对象，根据软骨染色结果确定软骨不同层区的厚度尺寸，制备缺损软骨试件；给缺损软骨分别施加滑动载荷和滚压载荷，采用数字图像相关技术研究缺损形式和载荷工况对软骨损伤演化过程和传质过程的影响，进行参数研究，考虑缺损的位置，形状和深度以及压缩量大小和加载速率的影响；探索微观组织结构，包括胶原纤维含量、分布方式和蛋白多糖含量对损伤演化和传质过程的影响；对软骨损伤演化和传质过程进行数值模拟和参数研究，依据细观损伤力学理论建立软骨损伤演化数学模型，总结缺损软骨损伤演化的规律。项目的成果对于预测复杂条件下的损伤演化结果和软骨寿命，修复缺损软骨和防治骨关节炎疾病具有重要意义。

关节软骨从微损伤到形成骨关节炎，往往需要几年、十几年甚至几十年的时间，给人们带来很大痛苦。软骨的损伤与力学环境有重要关系，研究关节软骨的损伤演化力学机制，对认识关节软骨的损伤演化规律和软骨疾病的防治有重要意义。对此做了以下几方面研究：.第一，发明一种滚压加载生物反应器。此反应器用门桥结构固定试件，便于安装；通过门桥上的横向和纵向螺杆调节软骨与压头的相对位置；门桥在实验过程中放置在恒温37℃的液体槽内，使实验尽量满足体内环境。.第二，软骨损伤演化过程的仿真研究。建立二维纤维增强的多孔粘弹性软骨计算模型，考虑纤维分布、孔隙率、弹性模量和渗透率随软骨深度的变化关系。参数化研究软骨损伤演化过程，研究发现软骨优先沿着纤维的切向方向扩展，损伤到一定深度后沿相邻纤维的切向向上演化，直到断裂形成软骨碎块。软骨碎块的形成是软骨损伤演化的结果，并且碎块的大小与初始缺损深度有直接关系。从最大切应变，间质液压和间质流速方面考虑，发现初始损伤形状只在损伤演化的初期有影响，矩形缺口的软骨周围切应变最小，间质液压最大，间质流速最慢，建议手术修复时采用圆柱形切口。载荷类型和载荷速度都对软骨损伤演化的速度有影响，理论模型显示损伤深度在50%以内，损伤演化速度比较缓慢，损伤深度在50%~80%时，损伤演化速度较快，损伤深度达到80%后，损伤演化速度减慢，缺口面积增大。.第三，缺损软骨力学性能的体外实验研究。采用数字图像相关技术，结合生物反应器做了缺口软骨的力学性能实验，研究发现切应变是造成软骨损伤演化的主要因素，损伤影响软骨的蠕变性能，各层区的蠕变应变值随着时间的增加而逐渐增大，应变变化率随着时间的增加逐渐减小，直到趋于平缓；随着软骨缺损深度的增加，软骨缺损周围各层区的蠕变应变值增大；缺损底角处的蠕变值大于缺损底部中间的蠕变值。.本课题培养硕士研究生3名，已发表文章12篇，其中5篇SCI检索，1篇EI检索。申请发明专利2项，参加学术会议10人次。