髋臼后柱顺行螺钉固定钉道的有限元分析

Finite element analysis on tracks of antegrade screw for fixation of acetabular posterior column

[目的]分析髋臼后柱顺行骨通道螺钉固定的生物力学特征。[方法]64排螺旋CT扫描健康成年男性志愿者骨盆数据,建立志愿者骨盆三维有限元模型,设计出髋臼后柱几何骨通道螺钉钉道和两个任意钉道。测定未置入螺钉及置入螺钉时髋骨和螺钉的Von Mises应力与位移。[结果]有螺钉固定的骨盆皮质骨应力比正常骨盆稍大,使用几何螺钉时骨盆皮质骨应力最小,随着载荷的增大,各组模型皮质骨承受Von Mises应力均显著增加(P<0.05);无论骨盆是否有螺丝钉,骨小梁应力几乎相同,相同载荷下,正常髋骨受力应力最小,自由钉道2组螺钉受力最大,各组间差异有统计学意义(P<0.05);正常骨盆的位移明显大于螺钉固定的骨盆位移,各载荷条件下,几何钉道螺钉所承受应力最大(P<0.05),但几何钉道螺钉固定的骨盆位移最小(P<0.05)。随着载荷力的增大,各组螺钉所受应力逐渐加大(P<0.05)。[结论]几何钉道的螺钉发生应力集中大,但位移较小,是髋臼后柱骨折顺行骨通道螺钉置入的最优骨通道。

[Objective]To analyze the biomechanical characteristics of different tracks of anterograde screw placed for fixation of ace⁃tabular posterior column.[Method]The pelvic data of a healthy adult male volunteer who underwent 64-slice spiral CT scanning were pro⁃cessed to create three-dimensional finite element models.After that,anterograde screw placement in the geometric tract and other two tracts in arbitrary manner were mimicked on the models.Under different loadings,the Von Mises and displacement of the bone and screws were measured and compared among the intact bone model,the geometric tract model and other two models with arbitrary track.[Results]As increasing loading,the Von Mises stresses significantly increased on the acetabular bones in each model(P<0.05).Under the same load⁃ing,the intact model had the least stress,while the arbitrary track 2 model had the greatest stress with statistical significances among groups(P<0.05).Of the models with screw placements,the geometric model proved closed to the intact group mostly regarding the stress on the acetabular bones.In addition,the Von Mises stresses on the screw also significantly increased as the loads enhancing in the models with screw placement(P<0.05).Under the corresponding load,the geometric model had the greatest stress on the screw,whereas the least displacement of the screw among the 3 models with screw placement(P<0.05).[Conclusion]The geometric tract of antegrade screw place⁃ment might achieve the best fixation of acetabular posterior column with minimal stress concentration and displacement of the screw.