前柱伴后半横形髋臼骨折三种固定的有限元分析

A finite element analysis on three fixations for anterior column and posterior hemi-transverse acetabular fractures

[目的]利用有限元方法研究第二代动力化前路方形区钛板螺钉系统(dynamic anterior plate-screw system for quadri-lateral area,DAPSQ)固定髋臼前柱伴后半横形骨折(anterior column and posterior hemi-transverse,ACPHT)的生物力学稳定性。[方法]通过有限元软件建立髋臼ACPHT骨折的骨盆模型和三组内固定模型:分别采用第二代DAPSQ、双柱钛板(double-column plate,DCP)及前柱铁板联合后柱拉力螺钉(anterior column plate and posterior column lag screw,ACPPS)固定。模拟站立位下加载600N生理载荷,比较各组应力分布情况、骨折线路径上各节点的平均位移及内固定的应力遮挡率。[结果]骨折线路径上各节点的平均位移为DAPSQ组<DCP组<ACPPS组,其中,DAPSQ组与DCP组差异无统计学意义(P>0.05),ACPPS组与DAPSQ组和DCP组差异均有统计学意义(P<0.05)。三组内固定方式最大应力为组。应力遮挡率为DCP组〉DAPSQ组〉ACPPS组,其中,DCP组与DAPSQ组间差异无统计学意义(P>0.05),ACPPS组与DCP组和DAPSQ组的差异均有统计学意义(P<0.05)。[结论]第二代DAPSQ在固定髋臼ACPHT骨折时,其生物力学稳定性与DCP相当,并优于ACPPS。

[Objective]To explore the biomechanical stability of the second generation dynamic anterior plate-screw system for quadrilateral area(DAPSQ)in the fixation of anterior column and posterior hemi-transverse(ACPHT)acetabular fractures by using finite element method.[Methods]Using finite element software to build the pelvis model of ACPHT acetabular fractures.Three internal fixation models were created respectively,including the second generation DAPSQ,the double column plates(DCP)and an anterior column plate combined with posterior column lag screw(ACPPS).The displacement of fracture,stress distribution and stress shielding rate measured under 600 N load to imitate standing position were compared among the 3 groups.[Results]The displacement was ranked down-up in sequence of DAP-SQ<DCP<ACPPS,which proved statistically significant between ACPPS and DAPSQ,or DCP(P<0.05),whereas not statistically significant between DAPSQ and DCP(P>0.05).The maximus stress was arranged up-down in sequence of DAPSQ>DCP>ACPPS.However,the sequence up-down in term of stress shielding rate was DCP>DAPSQ>ACPPS,which was statistically significant between ACPPS and DAPSQ,or DCP(P<0.05),whereas not statistically significant between DAPSQ and DCP(P>0.05).[Conclusion]The second generation DAPSQ has quite comparable biomechanical stability to DCP,whereas is superior to ACPPS for fixation of ACPHT acetabular fractures.