锁定加压钢板与交锁髓内钉固定肱骨投掷骨折的有限元分析

Finite element analysis of the throwing fracture of humerus fixed with locking compression plates and interlocking intramedullary nails

目的通过三维有限元法对锁定加压钢板和交锁髓内钉固定肱骨投掷骨折的生物力学稳定性进行比较,为临床应用提供理论参考。方法分别建立前外侧锁定加压钢板、后侧锁定加压钢板、顺行髓内钉、逆行髓内钉固定肱骨投掷骨折的三维有限元模型。应用有限元分析法在相同的加载和约束条件下模拟轴向压缩、逆时针扭转和三点弯曲三种工况,评价各组内固定最大等效应力、肱骨骨折块及骨折断端最大等效应力。结果 (1)内固定最大等效应力:锁定加压钢板置于前外侧较后侧最大应力值小;逆行较顺行髓内钉在压缩工况最大应力值更大,扭转和弯曲工况较小;(2)骨折块最大综合位移:髓内钉较锁定加压钢板组大,锁定加压钢板置于前外侧较后侧大,顺行髓内钉较逆行髓内钉大;(3)骨折断端最大等效应力:锁定加压钢板较髓内钉组骨折断端最大应力大且应力分布均匀。结论应用锁定加压钢板较髓内钉治疗肱骨投掷骨折更加稳定且应力均匀;锁定加压钢板置于后侧较前外侧更稳定但应力略大;逆行髓内钉稳定性优于顺行髓内钉。

Objective To explore and compare the biomechanical properties of the throwing fracture of humerus fixed with locking compression plates and interlockingintramedullary nails using finite element analysis, and therefore to provide theoretic reference for clinic application. Methods 3D FE models of the throwing fracture of humerus fixed with locking compression plates in anterolateral and posterior,retrograde and antegrade interlocking intramedullary nails were developed. Each mode was tested in axial compression, bending and anticlockwise torsion. The von- Mises and total deformation of internal fixities,humerus and fracture end were used to compare. Results The maximum stress of the anterolateral plate placement was smaller than the posterior plate placement. Under compression loading, the maximum stress of the retrograde intramedullary nail was smaller than the antegrade intramedullary nail group while the opposite results were obtained under the bending and anticlockwise torsion loadings. The maximum deformation of humerus of locking compression plate groups was smaller than the intramedullary nail groups, the anterolateral plate group was greater than the posterior group, and the antegrade intramedullary nail group was greater than the retrograde group. The stress distribution of fracture end of the locking compression plate groups was more uniform than the interlocking nail groups and had a larger maximum stress. Conclusions The throwing fracture of humerus fixed with locking compression plate is more stable and the stress distribution is more uniform than that fixed interlocking intramedullary nail. Locking compression plate in posterior placement is more stable than the anterolateral placement but have a larger maximum stress. Fixation with retrograde intramedullary nail is more stable than that with the antegrade intramedullary nail.