骶髂关节脱位钉板内固定与关节拉力螺钉内固定两种置入方法的三维有限元分析

Three-dimensional finite element analysis of screw-plate fixation and joint lag screws fixation for sacroiliac joint dislocation

背景:有限元法能对复杂的结构、形态、载荷和材料力学性能进行应力分析比较,模拟的条件更接近正常,结果更加可信,已经是骨科生物力学研究中的重要手段。目的:以有限元分析方法建立骨盆骶髂关节(单侧)脱位模型,比较前路钉板内固定及骶髂关节拉力内固定治疗后的生物力学稳定性。方法:在正常骨盆三维有限元模型的基础上,截断骶髂关节间的骶髂前后韧带(包含骶髂骨间韧带)以及骶结节韧带和骶棘韧带等盆底韧带,造成骶髂关节脱位。分别在前路钉板内固定系统(共2块重建钢板6枚螺钉)及骶髂关节拉力螺钉内固定(2枚拉力螺钉)两种固定方法的模型上,加载后进行非线性有限元分析。计算该加载方式下的骨盆应力、应变及位移的分布情况。结果与结论:建立了高精度骨盆骶髂关节脱位两种内固定的三维有限元模型。通过应力应变云图分析与比较后发现,采用骶髂关节拉力螺钉内固定相对于前路钢板内固定移位的总位移小,应力分布均匀,无明显高度集中现象,固定强度更大,固定后的骨盆更稳定。利用有限元方法分析骨盆骶髂关节脱位两种内固定生物力学稳定性,具有较高真实性、精确度和可重复性,结果与其他生物力学实验结果相一致,能满足临床骨盆损伤研究的需要。

BACKGROUND：Finite element analysis（FEA）can be applied to compare stress of complicated structure,morphology,load,and material property,and it is being considered as an important method in orthopaedic biomechanical research. OBJECTIVE：To prepare sacroiliac joint dislocation models by FEA,and to compare biomechanics stability of two internal fixation treatments for sacroiliac joint dislocation. METHODS：All the ligaments situated in half sacroiliac joint were cut on the normal three-dimensional finite element model of pelvis.These ligaments include anterior sacroiliac ligaments,posterior sacroiliac ligaments,interosseous sacroiliac ligaments,sacrotuberous ligaments and sacrospinous ligaments.Thus,the pelvic model of sacroiliac joint dislocation was established.In order to simulate the treatment with plates and screws on dislocation of pelvic sacroiliac joint via anterior path,the two reconstructive plates and the six standard screws were added into the model,as well as the two sacroiliac joint lag screws via posterior path.Then,the same load was exerted on different model respectively.At the end,the none-line solution was analyzed. MAIN OUTCOME MEASURES：The stress,strain and displacement nephograms were obtained under axial load. RESULTS AND CONCLUSIONS：The high-precision three dimensional finite element model of pelvic sacroiliac dislocation was established.The biomechanical stability and intensity of the two methods of internal fixations were analyzed and compared by the stress-strain nephogram.The consequences indicated that the fixation stability of two sacroiliac joint lag screws was larger than that of two reconstruction plates via anterior path.The total displacement of the former was less then that of the latter,and the stress of the former was not clearly concentrated on some sites.The fixation intensity of the former was larger,and the stability of fixed pelvis was better.The method on analyzing biomechanics stability of two internal fixation treatments on sacroiliac joint dislocation by the three-dimensional finite element analysis has the advantages of the higher authenticity,precision and repeatability.The result is identical to those of other experimental methods.Accordingly,this method can be applied to the research of pelvis injuries clinically.