LC-Ⅱ螺钉固定DayⅠ型骨盆新月形骨折的生物力学研究

Biomechanical Study of LC-II Screw for DayI Crescent Fracture of Pelvis

目的 探讨2根LC-Ⅱ螺钉与2块钢板在DayI型骨盆新月状骨折内固定中的应用。方法 选取一位志愿者的骨盆CT数据,通过数字医学软件建立骨盆三维模型;根据骨盆新月形骨折的Day分型,规划出DayⅠ型骨折。分别建立生理状态模型(intact),LC-Ⅱ螺钉固定模型(DayⅠ-螺钉)和骶髂关节钢板固定模型(DayⅠ-钢板)。对3组模型施加同样的载荷和约束,比较3种模型的变形和应力分布情况。结果 在各种荷载形式下,intact、DayⅠ-螺钉、DayⅠ-钢板模型的变形变化规律基本一致。在前屈载荷作用下,intact、DayⅠ-螺钉、DayⅠ-钢板模型的最大变形量为0.57 mm, 0.76 mm, 0.68 mm。与DayⅠ-螺钉试验模型比较,DayⅠ-钢板试验模型在各种载荷方式下,其应力值均有显著增加,在垂直载荷方式下,其应力值上升320%,前屈134%,后伸211%,左侧弯339%,右侧弯208%,左旋转321%,右旋转284%。结论 2根LC-Ⅱ螺钉和2块钢板都可以维持DayⅠ型骨盆骨折的稳定,但由于钢板受压过大,易发生疲劳破坏及螺钉松脱等问题,因此,如果能闭合复位成功,则宜采用2根LC-Ⅱ螺钉固定。

Objective Application of 2 LC-II screws and 2 steel plates in the internal fixation of DayI pelvic floor crescent fracture.Method Select the CT data of one volunteer and establish the D model by digital medical software,based on the Day classification of pelvic crescent fracture.The physiological state model(intact),LC-II screw fixation model(DayI-screw)and sacroiliac joint plate fixation model(DayI-plate)were established,respectively.The same load and constraints were applied to the 3 sets of models,and the deformation and stress distribution of the 3 models were compared and analyzed.Results The deformation changes of intact,DayI-screw and DayI-plate model are basically the same.The maximum deformation of the intact,DayI-screw,and DayI-plate model was 0.57 mm,0.76 mm,and 0.68 mm.Compared with DayI-plate and DayI-screw test models,the stress value of DayI-plate and DayI-screw test models increased significantly under various load modes,in which the stress value increased by 320%,134%,forward extension 211%,left bend 339%,right bend 208%,left rotation 321%,and right rotation 284%.Conclusion Two LC-II screws and two metal sheets can maintain the stability of DayI pelvic area,but due to the excessive pressure of the metal sheet between the vertebrae,prone to fatigue damage and screw release,therefore,if the operation can be successfully completed,two LC-II screws should be used.