钙化软骨层硬度变化对骨软骨结构应力影响的有限元分析

Effect of stiffness change of calcified cartilage zone on the stress of osteochondral structure using finite element analysis

背景:从少年到成年,再到老年阶段,钙化软骨层的硬度逐渐增加。然而钙化软骨层的硬度变化对关节骨软骨结构的应力有何影响目前并不十分清楚。目的:运用有限元分析法,探讨钙化软骨层的硬度改变对关节骨软骨结构应力的影响。方法:建立包含透明软骨、钙化软骨层和软骨下骨的骨软骨结构有限元模型,并模拟少年、成年和老年时期的特点,建立对应的钙化软骨层柔软、正常和坚硬有限元模型,施加压缩载荷(0.5-3.0MPa),对比分析3个模型中3层结构的应力分布情况。结果与结论:(1)当钙化软骨层坚硬时,其应力峰值比正常时增加26.51%,而透明软骨的应力峰值与正常时相似;(2)当钙化软骨层柔软时,其自身和透明软骨的应力峰值分别比正常时减少52.09%和33.93%,且当载荷大于1.0 MPa时模型失效;(3)可见坚硬的钙化软骨层承受着更大的应力,并对透明软骨无明显影响;而柔软的钙化软骨层使自身和透明软骨受到的应力明显小于正常,并造成骨软骨结构仅能承受较小的压缩负荷。

BACKGROUND:From childhood to adulthood,and to old age,the stiffness of calcified cartilage zone increases gradually.But it is poorly understood that the effect of stiffness change of calcified cartilage zone on the stress of articular osteochondral structure.OBJECTIVE:To investigate the effect of stiffness change of calcified cartilage zone on the stress of articular osteochondral structure using finite element analysis.METHODS:A finite element model of osteochondral structure was established with hyaline cartilage,calcified cartilage zone and subchondral bone.Then,by simulating the features of childhood,adulthood and old age,three corresponding finite element models were created:calcified cartilage zone soft model,calcified cartilage zone normal model,and calcified cartilage zone hard model.Compression loads(0.5-3.0 MPa)were respectively applied to the three models so as to compare the stress distributions of three layers among three models.RESULTS AND CONCLUSION:(1)When calcified cartilage zone became hard,the maximum stress of itself was 26.51%more than normal,whereas the maximum stress of hyaline cartilage was similar to the normal.(2)When calcified cartilage zone became soft,the maximum stress of itself and hyaline cartilage was 52.09%and 33.93%less than normal,respectively.Besides,the calcified cartilage zone soft model would be out of action when the compression load was higher than 1.0 MPa.(3)In summary,hardened calcified cartilage zone suffers more stress than normal and does no effect on the stress of hyaline cartilage.Softened calcified cartilage zone renders the stresses of itself and hyaline cartilage to be much less than normal and allows osteochondral structure to bear small compression loads.