中日友好医院分型股骨头坏死腓骨植入治疗的三维有限元分析

Three-dimensional finite element analysis of fibula implantation for China-Japan Friendship Hospital type osteonecrosis of femoral head

背景:研究报道股骨头坏死的保髋疗效与外侧柱存留密切相关,中日友好医院分型是根据三柱结构确立的,对股骨头塌陷的预测准确性高。目的:建立股骨头坏死中日友好医院分型各分型仿真的三维有限元模型,通过有限元分析各分型腓骨植入的力学变化,探讨外侧柱存留对保髋疗效的意义,为该分型的塌陷精准预测提供基础。方法:建立正常股骨头、中日友好医院分型(M型、C型、L1型、L2型、L3型)股骨头坏死及其腓骨植入3组11种三维有限元模型,运用ANSYS软件进行有限元分析计算,观察各组模型的最大应力值、最大位移值及股骨头内部载荷传递模式。结果与结论:①坏死组位移最大,应变最大,且因坏死分型不同而位移不同,位移变化如下:M型<C型<L1型=L2型<L3型;腓骨植入组位移恢复均低于正常组,且因坏死分型不同而位移恢复不同,位移变化如下:M型<C型<L1型<L2型<L3型,修复后的坏死股骨头的位移下降幅度从外侧柱到内侧柱逐级变小,均低于正常股骨头的最大位移。②坏死后的股骨头载荷区表面应力云图呈现的峰值均高于正常组,坏死M型基本接近正常,坏死C型峰值高出正常74.5%,坏死L型峰值均高出正常100%以上;坏死M型术后的峰值不但比术前下降14.2%,也低于正常水平;坏死C型术后的峰值比术前下降5.3%,但高于正常水平;坏死L型术后的峰值比术前下降,但均明显高于正常水平。③正常股骨头内部的载荷传递是连续的,传导路径从股骨头外侧柱到股骨矩。坏死组中M、C型的股骨头内部载荷传递是连续的,M型的传导基本与正常一致,C型的传导到股骨矩的应力减少;L1、L2、L3型的股骨头内部的载荷传递出现中断,应力出现断崖式的变化,无法传导到股骨矩,导致股骨头载荷区应力集中。腓骨植入组中的股骨头内部重建了一定有效的载荷传递模式,所有分型的传导都出现股骨矩处的应力集中,部分载荷通过腓骨传递到股骨矩上,正常载荷传递模式得到部分恢复。④提示中日友好医院分型腓骨植入能在一定程度上预防坏死股骨头的塌陷,坏死区位置及大小至关重要,坏死越靠近外侧柱越容易塌陷,修复越困难,外侧柱的存留是精准预测股骨头塌陷的重要考虑因素。

BACKGROUND:It is reported that the hip-conserving effect of osteonecrosis of femoral head is closely related to the retention of lateral column.The classification of China-Japan Friendship Hospital is based on the three-column structure,and the prediction accuracy of femoral head collapse is high.OBJECTIVE:To establish a three-dimensional finite element model for China-Japan Friendship Hospital classification of femoral head necrosis,and to analyze the mechanical changes of fibula implantation in each classification by finite element method,and to explore the significance of lateral column retention in hip preservation,so as to provide a basis for precise prediction of collapse of the classification.METHODS:Three groups of 11 kinds of three-dimensional finite element models of normal femoral head,China-Japan Friendship Hospital type femoral head necrosis(type M,type C,type L1,type L2,type L3)and fibula implantation were established.The finite element analysis was carried out by ANSYS software.The maximum stress,maximum displacement and load transfer mode of proximal femur were observed in each group.RESULTS AND CONCLUSION:(1)In the necrosis group,the strain was the largest,and the displacement was different due to the different types of necrosis.The displacement changes were as follows:Type M<type C<type L1=type L2<type L3.The displacement recovery of fibula implantation group was lower than that of the normal group,and the displacement recovery was different due to the different necrosis types.The displacement changes were as follows:Type M<type C<type L1<type L2<type L3.The reduction range of the displacement of the repaired necrotic femoral head gradually decreased from the lateral column to the medial column,which was lower than the maximum displacement of the normal femoral head.(2)The peak value of the stress nephogram of the loading area of the femoral head after necrosis was higher than that of the normal group.The peak value of necrotic type M was nearly normal.The peak value of necrotic type C was 74.5%higher than that of the normal group,and the peak value of necrotic type L was more than 100%higher than that of the normal group.The peak value of necrotic type M after operation was not only 14.2%lower than that before operation,but also was lower than that of the normal group.The peak value of necrotic type C after operation was 5.3%lower than that before operation,but higher than that of normal group.The peak value of necrosis type L after operation was lower than that before operation,but significantly higher than the normal level.(3)The load transfer in the normal femoral head was continuous.The conduction path was from the lateral column of the femoral head to the femoral moment.In the necrosis group,the internal load transfer of types M and C femoral head was continuous,and the conduction of type M was basically consistent with normal.The stress of type C conduction to femoral moment was reduced.The load transfer of L1,L2 and L3 type femoral head was interrupted.The stress changed in cliff type,and was unable to transmit to femoral moment,resulting in stress concentration in load area of the femoral head.A certain effective load transfer mode was reconstructed in the femoral head of the fibula implantation group,and the stress concentration at the femoral moment occurred in all types of conduction.Part of the load was transferred to the femoral moment through fibula,and the normal load transfer mode was partially restored.(4)China-Japan Friendship Hospital type fibula placement can prevent the collapse of the femoral head to a certain extent.The location and size of the necrosis area are very important.The closer the necrosis is to the lateral column,the easier it is to collapse and the more difficult it is to repair.The retention of the lateral column is an important factor for accurate prediction of the collapse of the femoral head.