两种骶髂螺钉固定双侧骶骨骨折的稳定性比较

Stability of two kinds of sacroiliac screw fixation of bilateral sacral fracture： a comparative study

目的比较不同固定方式下，采用加长或普通两类骶髂螺钉固定治疗双侧骶骨骨折的稳定性。方法使用三维有限元方法，建立双侧骶骨纵行骨折（Tile C型）模型，模拟使用加长、普通两类骶髂螺钉采用7种不同固定方式进行固定，并在模拟站立位状态下比较骨盆后环的竖直稳定性和旋转稳定性。结果竖直方向600N力载荷加载后，骶1上表面的向下位移和后旋角位移比较显示，骶1、骶2层面各自1枚加长骶髂螺钉均比同层面的2枚双向普通骶髂螺钉固定的稳定性高；骶1、骶2层面各置1枚加长骶髂螺钉的组合比两个层面各双向置2枚普通骶髂螺钉的组合固定的稳定性高；骶1和骶2双层面加长骶髂螺钉组合固定的稳定性明显优于单层面的加长骶髂螺钉固定；骶1和骶2双层面双向4枚普通骶髂螺钉组合固定的稳定性明显优于单层面双向2枚普通骶髂螺钉组合固定，也明显优于双层面双向2枚普通骶髂螺钉组合固定。在竖直稳定性方面，骶2层面加长和普通骶髂螺钉固定均优于骶1层面的相应固定；在旋转稳定性方面，骶1层面的加长和普通骶髂螺钉固定均优于骶2层面的相应固定。结论针对Tile C型双侧骶骨纵行骨折，应尽可能选择骶1、骶2加长骶髂螺钉固定，二者组合是最佳选择。

Objective To compare the stability of lengthened or conventional sacroiliac screws in patients with bilateral sacral fracture by using various approaches for fixation. Methods Bilateral sacral longitudinal fracture models （Tile C） were constructed via three-dimensional finite element analysis and were subjected to virtual fixation by using 7 approaches in which lengthened or conventional sacroiliac screw was applied. Vertical and rotational stability of posterior pelvic ring was compared via mimicking standing conditions. Results After being loaded with 600 N vertically, each lengthened sacroiliac screw yielded higher fixation stability than 2 bidirectional conventional sacroiliac screws at both S1 and S2 planes, as shown by comparison on the downward translation and backward angle displacement at the superior surface of S1. The combination of lengthened sacroiliac screw at both S1 and S2 was evidenced to be of higher stability than 2 bidirectional conventional sacroiliac screws at each plane combined. Higher fixation stability was found in lengthened sacroiliac screws at both S1 and S2, but not at either plane. Additionally, fixation adopting 4 bidirectional conventional sacroiliac screws each at S1 and S2 conferred markedly higher stability than 2 bidirectional sacroiliac screws at either plane as well as at both planes. Both lengthened and conventional sacroiliac screws at S2 were superior to that at S1 in terms of vertical stability. Contrarily, both lengthened and conventional sacroiliac screws conferred preferable rotational stability at S1, but not at S2. Conclusion Lengthened sacroiliac screw at either S1 or S2, and in particular the combination of both planes, may be the candidates for Tile C bilateral sacral longitudinal fracture.