第二代动力化前路方形区钛板螺钉固定髋臼骨折有限元分析

Finite element analysis on the second-generation dynamic anterior plate-screw system for quadrilateral area of acetabular fractures

[目的]采用有限元分析法研究第二代动力化前路方形区钛板螺钉系统(DAPSQ)在方形区排钉分布特点,并与传统前路重建钛板加1/3管型比较。[方法]建立左侧高位髋臼双柱骨折模型,分别采用DAPSQ方形区螺钉下5种排钉方式和前路重建钛板加1/3管型(C)进行固定。模拟600 N垂直载荷,分析6种内固定方式在骨盆站位、坐位、站位+健侧旋转和站位+患侧旋转(扭矩8 N/m)时方形区骨折位移和内固定承受应力情况。[结果]在站位、坐位、健侧旋转和患侧旋转下,各组方形区骨折线位移表现为C>A1>A2>A3>A4>B,且两两比较时C组与其余5组差异均具有统计学意义(P<0.05)。站位、向健侧和患侧旋转时,C组内固定峰值应力最大,坐位时最小。6种内固定模型在站位后继续向健侧旋转均表现为峰值应力减小,继续向患侧旋转均表现为峰值应力增大。[结论]第二代DAPSQ在固定髋臼高位双柱骨折生物力学稳定性优于传统前路重建钛板和1/3管型,且方形区螺钉置钉时以近端第一枚螺钉最为重要。

[Objective]To explore biomechanical characteristics of the second-generation dynamic anterior plate-screw system for quadrilateral area of acetabular fractures(DAPSQ)by comparison with anterior constructive plate plus 1/3 tube buttress-plate.[Methods]The left acetabular upper double-column fractures model was established by finite element modeling software.The fractures were fixed by DAPSQ in 5 types of screw placement at quadrilateral area(the A1,A2,A3,A4 and B groups),and anterior constructive plate plus 1/3 tube buttress plate(the C group)respectively.The fracture displacement and stress distribution of the internal fixation were assessed under 6000 N axial loading at standing,sitting,rotation to the affected side,and rotation to the non-affected side.[Results]The displacement of fracture gaps was ranked up-down in the sequence of C>A1>A2>A3>A4>B,with statistically significant differences between group C and the remaining 5 groups at standing,sitting,rotation to the affected side,and rotation to the non-affected side(P<0.05).The Von-Mises stress in the C group was the maximal at sitting,and became minimal at standing,rotation to the affected side,and rotation to the non-affected side.In addition,the Von-Mises stress in the 6 fixation models decreased from standing to rotation to the non-affected side,and then increased to rotation to the affected side.[Conclusion]The biomechanical stability of the second generation DAPSQ is superior to the anterior constructive plate plus 1/3 tube buttress-plate for acetabular upper both-column fractures,which improves as screws placed from anterior to posterior quadrilateral area,whereas the stability is deteriorate as rotation to the affected side.