Kandziora F, Pflugmacher R, Schäfer J, Born C, Duda G, Haas N P, Mittlmeier T
Unfall- und Wiederherstellungschirurgie, and the Strahlenklinik und Poliklinik Universitätsklinikum Charité der Humboldt Universität Berlin, Campus Virchow-Klinikum, Berlin, Germany.
Spine (Phila Pa 1976). 2001 Sep 1;26(17):1850-7. doi: 10.1097/00007632-200109010-00007.
An in vitro biomechanical study of cervical spine interbody fusion cages using a sheep model was conducted.
To evaluate the biomechanical effects of cervical spine interbody fusion cages, and to compare three different cage design groups.
Recently, there has been a rapid increase in the use of cervical spine interbody fusion cages as an adjunct to spondylodesis. These cages can be classified into three design groups: screw, box, or cylinder designs. Although several comparative biomechanical studies of lumbar interbody fusion cages are available, biomechanical data for cervical spine constructs are lacking. Additionally, only limited data are available concerning comparative evaluation of different cage designs.
In this study, 80 sheep cervical spines (C2-C5) were tested in flexion, extension, axial rotation, and lateral bending with a nondestructive stiffness method using a nonconstrained testing apparatus. Three-dimensional displacement was measured using an optical measurement system (Qualysis). Complete discectomy (C3-C4) was performed. Cervical spine interbody fusion cages were implanted according to manufacturers' information. Eight spines in each of the the following groups were tested: intact, autologous iliac bone graft, two titanium screws (Novus CTTi; Sofamor Danek, Koln, Germany), two titanium screws (BAK-C 8 mm; Sulzer Orthopedics, Baar, Switzerland), one titanium screw (BAK-C 12 mm; Sulzer Orthopedics), carbon box (Novus CSRC; Sofamor Danek), titanium box (Syncage; Synthes, Bochum, Germany), titanium mesh cylinder (Harms; DePuy Acromed, Sulzbach, Germany), titanium cylinder (MSD; Ulrich, Ulm, Germany), and titanium cylinder (Kaden; BiometMerck, Berlin, Germany). The mean apparent stiffness values were calculated from the corresponding load-displacement curves. Additionally, cage volume and volume-related stiffness was determined.
After cervical spine interbody fusion cage implantation, flexion stiffness increased, as compared with that of the intact motion segment. On the contrary, rotation stiffness decreased after implantation of a cervical spine interbody fusion cage, except for the Novus CSRC, Syncage, and Kaden-Cage. If two screws were inserted (Novus CTTi and BAK-C 8 mm), there was no significant difference in flexion stiffness between screw and cylinder design groups. If one screw was inserted (BAK-C 12 mm), flexion stiffness was higher for cylinder designs (P < 0.05). Extension and bending stiffness were always higher with cylinder designs (P < 0.05). Volume-related stiffness for flexion extension and bending was highest for the Harms cage (P < 0.05). There was no difference for rotation volume-related stiffness between Harms and Syncage.
The biomechanical results indicate that design variations in screw and cylinder design groups are of little importance. In this study, however, cages with a cylinder design were able to control extension and bending more effectively than cages with a screw design.
采用绵羊模型对颈椎椎间融合器进行体外生物力学研究。
评估颈椎椎间融合器的生物力学效应，并比较三种不同的融合器设计组。
近年来，颈椎椎间融合器作为脊柱融合术的辅助器械，其使用迅速增加。这些融合器可分为三种设计组：螺钉型、盒型或圆柱型。虽然有几项关于腰椎椎间融合器的比较生物力学研究，但缺乏颈椎结构的生物力学数据。此外，关于不同融合器设计的比较评估仅有有限的数据。
在本研究中，使用非约束测试装置，采用无损刚度法对80个绵羊颈椎（C2 - C5）进行屈伸、轴向旋转和侧弯测试。使用光学测量系统（Qualysis）测量三维位移。进行全椎间盘切除术（C3 - C4）。根据制造商的说明植入颈椎椎间融合器。对以下每组中的8个脊柱进行测试：完整组、自体髂骨移植组、两枚钛螺钉（Novus CTTi；Sofamor Danek，科隆，德国）、两枚钛螺钉（BAK - C 8 mm；Sulzer Orthopedics，巴尔，瑞士）、一枚钛螺钉（BAK - C 12 mm；Sulzer Orthopedics）、碳盒型（Novus CSRC；Sofamor Danek）、钛盒型（Syncage；Synthes，波鸿，德国）、钛网圆柱型（Harms；DePuy Acromed，苏尔茨巴赫，德国）、钛圆柱型（MSD；Ulrich，乌尔姆，德国）和钛圆柱型（Kaden；BiometMerck，柏林，德国）。从相应的载荷 - 位移曲线计算平均表观刚度值。此外，确定融合器体积和与体积相关的刚度。
植入颈椎椎间融合器后，与完整运动节段相比，屈曲刚度增加。相反，植入颈椎椎间融合器后，旋转刚度降低，但Novus CSRC、Syncage和Kaden融合器除外。如果插入两枚螺钉（Novus CTTi和BAK - C 8 mm），螺钉型和圆柱型设计组之间的屈曲刚度无显著差异。如果插入一枚螺钉（BAK - C 12 mm），圆柱型设计的屈曲刚度更高（P < 0.05）。圆柱型设计的伸展和侧弯刚度总是更高（P < 0.05）。Harms融合器的屈伸和侧弯与体积相关的刚度最高（P < 0.05）。Harms和Syncage之间的旋转与体积相关的刚度无差异。
生物力学结果表明，螺钉型和圆柱型设计组的设计差异不太重要。然而，在本研究中，圆柱型设计的融合器比螺钉型设计的融合器能更有效地控制伸展和侧弯。
