Chen Hui, Yu Bin-sheng, Zheng Zhao-min, Lü You, Zhang Kui-bo, Liu Hui, Li Fo-bao
Department of Spinal Surgery, the First Affiliated Hospital, Sun Yat-Sen University, Guangzhou 510080, China.
Zhonghua Wai Ke Za Zhi. 2008 Aug 1;46(15):1179-82.
To biomechanically compare the stability of the short and long iliac screw fixation constructs in lumbo-iliac reconstruction.
Seven adult human embalmed cadavers (L(3)-pelvis) were used. Using posterior spinal fixation system, L(4)-S(1) pedicle screw fixation was performed. This was defined as intact state of the sacroiliac joint. After the intact test, total sacrum resection and L(4)-L(5)-pelvis reconstruction by pedicle screw and iliac screw with different lengths were performed as follow: short screw group (as the length of exceeding 2 mm over ischial notch) and long screw group (as the length of exceeding 2 mm over anterior inferior iliac spine). Using the 858 MTS material testing machine, biomechanical testing was performed under 800 N compression and 7 Nm torsion loading modes. At last, the axial pullout test of two iliac screws was executed. Construct stiffness in compression and torsion test, and maximum pullout force were analyzed.
Insertion lengths of the short and long iliac screw were (70 +/- 2) mm and (138 +/- 4) mm respectively. The lumbo-pelvic reconstruction using short and long iliac screw, respectively restored 53.3% +/- 13.6% and 57.6% +/- 16.2% of the initial stiffness in compression testing, and respectively harvested 55.1% +/- 11.9% and 62.5% +/- 9.2% of the initial stiffness in torsion testing. No significant difference was detected between the two reconstructions (P > 0.05), however, the compressive and torsional stiffness of the two techniques were markedly less than the intact condition (P < 0.05). The maximum pullout strength of long iliac screw was significantly higher than short screw (P < 0.05).
Under the physical loading, lumbo-pelvic fixation construct using the short iliac screw may obtain mechanical stability comparable to that by long iliac screw. The short iliac screw is only the half of the long iliac screw by length, could reduce the implantation risk. However, the long iliac screw behaves greater axial pullout force, should be applied as far as possible in the osteoporosis patient. The lumbo-pelvic reconstruction utilizing any length of iliac screw is difficult to restore the local stability.
对腰髂部重建中短髂骨螺钉和长髂骨螺钉固定结构的稳定性进行生物力学比较。
使用7具成年防腐尸体（L3 - 骨盆）。采用后路脊柱固定系统，进行L4 - S1椎弓根螺钉固定，将此定义为骶髂关节完整状态。完整测试后，进行全骶骨切除，并采用不同长度的椎弓根螺钉和髂骨螺钉进行L4 - L5 - 骨盆重建，具体如下：短螺钉组（长度超过坐骨切迹2 mm）和长螺钉组（长度超过髂前下棘2 mm）。使用858 MTS材料试验机，在800 N压缩和7 Nm扭转加载模式下进行生物力学测试。最后，对两枚髂骨螺钉进行轴向拔出试验，分析压缩和扭转试验中的结构刚度以及最大拔出力。
短髂骨螺钉和长髂骨螺钉的置入长度分别为（70±2）mm和（138±4）mm。使用短髂骨螺钉和长髂骨螺钉进行腰骨盆重建，在压缩试验中分别恢复了初始刚度的53.3%±13.6%和57.6%±16.2%，在扭转试验中分别获得了初始刚度的55.1%±11.9%和62.5%±9.2%。两种重建方式之间未检测到显著差异（P > 0.05），然而，两种技术的压缩和扭转刚度均明显低于完整状态（P < 0.05）。长髂骨螺钉的最大拔出强度明显高于短螺钉（P < 0.05）。
在物理载荷作用下，使用短髂骨螺钉的腰骨盆固定结构可获得与长髂骨螺钉相当的机械稳定性。短髂骨螺钉长度仅为长髂骨螺钉的一半，可降低植入风险。然而，长髂骨螺钉具有更大的轴向拔出力，在骨质疏松患者中应尽可能应用。采用任何长度髂骨螺钉的腰骨盆重建都难以恢复局部稳定性。
