Khodadadyan-Klostermann C, Schaefer J, Schleicher Ph, Pflugmacher R, Eindorf T, Haas N P, Kandziora F
Unfall- und Wiederherstellungschirurgie, Universitätsklinikum Charité der Humboldt Universität Berlin, Campus Virchow-Klinikum, Berlin.
Chirurg. 2004 Jul;75(7):694-701. doi: 10.1007/s00104-003-0786-4.
Due to a recent increase in the commercial availability of expandable cages for vertebral body replacement, this study was designed to gain more information about their biomechanical properties. All three expandable cages evaluated in this study are approved for clinical use, but little knowledge about their biomechanical properties exists.
Human thoracolumbar spines (T11 to L3) ( n=32) were tested in flexion, extension, axial rotation, and lateral bending with a nondestructive stiffness method. Three-dimensional displacement was measured using an optical measurement system. All motion segments were tested intact. After L1 corporectomy, cages were implanted and the following groups ( n=8 each) were tested: (1) meshed titanium cage (nonexpandable cage, DePuy Acromed), (2) X-tenz (expandable cage, DePuy Acromed), (3) Synex (expandable Cage, Synthes), and (4) VBR (expandable cage, Ulrich). Finally, posterior stabilization and posterior-anterior stabilization, both using USS (Synthes), and anterior plating (LCDCP, Synthes) was applied. The mean apparent stiffness values, ranges of motion, and neutral and elastic zones were calculated from the corresponding load/displacement curves.
No significant differences were found between the in vitro biomechanical properties of expandable and nonexpandable cages. Compared to the intact motion segment, isolated anterior stabilization using cages and anterior plating significantly decreased stiffness and increased range of motion in all directions. Additional posterior stabilization significantly increased stiffness and decreased range of motion in all directions compared to the intact motion segment. Combined anterior-posterior stabilization demonstrated the greatest stiffness results.
Design variations of expandable cages for vertebral body replacement do not show any significant effect on the biomechanical results. There was no significant difference found, between the biomechanical properties of expandable and non-expandable cages. After corporectomy, isolated implantation of expandable cages plus anterior plating was not able to restore normal stability of the motion segment. As a consequence, isolated anterior stabilization using cages plus LCDCP should not be used for vertebral body replacement in the thoraco-lumbar spine.
由于可扩张椎体置换融合器的商业可得性最近有所增加，本研究旨在获取更多关于其生物力学特性的信息。本研究评估的三种可扩张融合器均已获批临床使用，但对其生物力学特性了解甚少。
采用无损刚度法对人胸腰椎（T11至L3）（n = 32）进行前屈、后伸、轴向旋转和侧方弯曲测试。使用光学测量系统测量三维位移。所有运动节段均完整测试。在L1椎体切除术后，植入融合器，并对以下各组（每组n = 8）进行测试：（1）网状钛合金融合器（不可扩张融合器，DePuy Acromed），（2）X-tenz（可扩张融合器，DePuy Acromed），（3）Synex（可扩张融合器，Synthes），以及（4）VBR（可扩张融合器，Ulrich）。最后，分别采用USS（Synthes）进行后路固定和前后路联合固定，以及采用LCDCP（Synthes）进行前路钢板固定。根据相应的载荷/位移曲线计算平均表观刚度值、活动范围以及中性区和弹性区。
可扩张融合器和不可扩张融合器的体外生物力学特性之间未发现显著差异。与完整运动节段相比，单独使用融合器和前路钢板进行前路固定显著降低了刚度，并增加了各个方向的活动范围。与完整运动节段相比，额外的后路固定显著增加了刚度，并减小了各个方向的活动范围。前后路联合固定的刚度结果最佳。
用于椎体置换的可扩张融合器的设计变化对生物力学结果没有任何显著影响。可扩张融合器和不可扩张融合器的生物力学特性之间未发现显著差异。椎体切除术后，单独植入可扩张融合器加前路钢板无法恢复运动节段的正常稳定性。因此，在胸腰椎椎体置换中不应单独使用融合器加LCDCP进行前路固定。
