软骨缺损形状对组织工程修复区的力学影响

Mechanical impact of cartilage defect shape on tissue engineering restoration area

目的通过有限元仿真探究组织工程修复软骨缺损后缺损形状对修复区力学状态的影响。方法运用Abaous6.10软件建立软骨纤维增强的多孔黏弹性模型,包括软骨的两相结构、不同层区胶原纤维的作用、方向及渗透率的特征。在压缩载荷下分析缺损截面形状(矩形、梯形、圆弧形)和缺损深度(浅表层、中间层、深层、全层)对软骨修复区应力的影响。结果对于中间层缺损,矩形截面修复界面处的Mises应力最小,梯形次之,圆弧形最大。对于不同缺损深度,当弹性模量<0.3 MPa时浅表层修复界面处应力最大,其他缺损深度的应力相差不大;当>0.4 MPa时,应力由小到大依次为浅表层、中间层、全层、深层缺损;而在此之间时应力与泊松比大小有关。结论软骨缺损截面形状和深度对修复区应力都有影响,临床上可制作矩形缺损截面和不同的缺损深度,并选择合适的弹性模量和泊松比的软骨植入达到较好的修复效果。

Objective To investigate the mechanical impact on restoration area with defect shape by tissue engineering via finite element simulation. Methods The fiber-reinforced poroelastic model of cartilage was established by Abaqus software, including 2-phase structure, collagen fiber and permeability in different layers. Mises stress in restoration area with different cross-section shapes（rectangle, trapezoid, circular arc） and depths of defect section（superficial, middle, deep, full-thickness layer defect） under compressing were analyzed. Results For middle layer defect, Mises stress of rectangular section was the smallest, followed by that of trapezoid and circular arc section was the biggest. For different depths of defect, when elastic modulus was less than 0.3 MPa, Mises stress of surface layer defect was the biggest, and the differences among other defect depths were small .When elastic modulus was bigger than 0.4 MPa, the stress varied from small to large was superficial, middle, full-thickness, and deep layer defect. While elastic modulus was between 0.3 MPa and 0.4 MPa, the stress was related to Poisson ratio. Conclusion It is demonstrated that cross-section shape and depth of defect could influence stress in restoration area. In clinic, the rectangular cross-section and different defect depths can be made and choose the appropriate elastic modulus and Poisson ratio to achieve better repairing effect.