PURPOSE Sacropelvic fixation is frequently used in combination with thoracolumbar instrumentation for complex deformity correction and is commonly associated with pseudoarthrosis, implant failure and loosening. This study compared pedicle screw fixation (PED) with three different sacropelvic fixation techniques, namely iliac screws (IL), S2 alar-iliac screws (S2AI) and laterally placed triangular titanium implants (SI), all in combination with lumbosacral instrumentation, accounting for implant micromotion. METHODS Existing finite element models of pelvis-L5 of three patients including lumbopelvic instrumentation were utilized. Moments of 7.5 Nm in the three directions combined with a 500 N compressive load were simulated. Measured metrics included flexibility, instrumentation stresses and bone-implant interface loads. RESULTS Fixation effectively reduced the sacroiliac flexibility. Compared to PED, IL and S2AI induced a reduction in peak stresses in the S1 pedicle screws. Rod stresses were mostly unaffected by S2AI and SI, but IL demonstrated a stress increase. In comparison with a previous work depicting full osteointegration, SI was found to have similar instrumentation stresses as those due to PED. CONCLUSIONS Fixation with triangular implants did not result in stress increase on the lumbosacral instrumentation, likely due to the lack of connection with the posterior rods. IL and S2AI had a mild protective effect on S1 pedicle screws in terms of stresses and bone-implant loads. IL resulted in an increase in the rod stresses. A comparison between this study and previous work incorporating full osteointegration demonstrates how these results may be applied clinically to better understand the effects of different treatments on patient outcomes. These slides can be retrieved under Electronic Supplementary Material.

中文翻译：

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cro骨固定的生物力学：三种技术的综合有限元比较。

目的Sa骨盆腔固定术通常与胸腰椎器械结合使用以矫正复杂的畸形，并且通常与假性关节炎，植入物衰竭和松弛相关。这项研究比较了椎弓根螺钉固定（PED）与三种different骨固定技术，即骨螺钉（IL），S2 lar骨螺钉（S2AI）和侧向放置的三角形钛植入物（SI），并结合了腰s骨器械，占了植入微动。方法利用腰椎骨盆器械在内的三例患者骨盆L5的有限元模型。模拟了三个方向上7.5 Nm的力矩以及500 N的压缩载荷。测量的指标包括灵活性，器械应力和骨-植入物界面负荷。结果固定有效地降低了sa的柔韧性。与PED相比，IL和S2AI导致S1椎弓根螺钉的峰值应力降低。杆应力大部分不受S2AI和SI的影响，但IL显示应力增加。与先前描述的完全骨整合的工作相比，发现SI具有与PED相似的器械应力。结论三角植入物的固定并没有导致腰s骨器械压力的增加，这可能是由于缺乏与后杆的连接。IL和S2AI在应力和植骨负荷方面对S1椎弓根螺钉有轻微的保护作用。IL导致杆应力增加。这项研究与先前结合完全骨整合的工作之间的比较表明，如何将这些结果应用于临床，以更好地了解不同治疗对患者预后的影响。这些幻灯片可以在电子补充材料下找到。