Bioabsorbable interbody cages in a sheep cervical spine fusion model
Bioabsorbable interbody cages in a sheep cervical spine fusion model
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DOI：
10.1097/01.brs.0000137060.79732.78
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发表时间：
2004-09-01
期刊：
影响因子：
3
通讯作者：
Haas, NP
中科院分区：
文献类型：
--
作者：
Kandziora, F;Pflugmacher, R;Haas, NP
研究设计.一项使用绵羊颈椎椎体间融合模型的实验研究。比较自体三皮质髂嵴骨移植物与两个生物可吸收融合器的椎间融合，并确定三种椎间融合技术在1）保持术后牵引的能力、2）生物力学稳定性和3）组织学方面是否存在差异。椎间骨基质形成的特征。总结和背景数据。与金属融合器相比，生物可吸收融合器将是有益的;然而，目前没有合适的生物可吸收椎间融合器可用。24只绵羊接受了C3/C4椎间盘切除和融合术。使用了以下稳定技术：组1）自体三皮质髂嵴植骨（n=8）;组2）由70/30聚乙烯制成的生物可吸收融合器（L-丙交酯-共-D，L-丙交酯）（实验组）自体松质骨填充组（n=8）;组3）由聚合物-磷酸钙复合材料制成的生物可吸收融合器（Biomet Europe，多尔德雷赫特，荷兰），填充自体松质骨移植物（n=8）。分别在术前、术后和术后1、2、4、8和12周进行影像学扫描以确定椎间隙高度。12周后，处死动物，使用屈曲和伸展的功能性X线片评价融合部位。定量计算机断层扫描用于评估骨矿物质密度、骨矿物质含量和骨痂体积。在屈曲、伸展、轴向旋转和侧弯时进行生物力学测试，以确定刚度、ROM以及中性区和弹性区。通过组织形态学和组织形态计量学分析评估与生物可吸收椎间融合器相关的融合和异物反应。在12周的时间内，聚合物-磷酸钙复合椎间融合器的椎间隙高度值显著高于骨移植物和聚（L-丙交酯-co-D，L-丙交酯）椎间融合器。此外，聚合物-磷酸钙复合材料椎间融合器在轴向旋转和侧向弯曲方面表现出比其他组显著更高的刚度和更低的ROM、中性区和弹性区。然而，定量计算机断层扫描显示，12周后，8个聚合物-磷酸钙复合椎间融合器中有6个出现裂缝。组织学上，聚合物-磷酸钙复合椎间融合器组的骨体积/总体积比和融合率最高。尽管聚（L-丙交酯-co-D，L-丙交酯）椎间融合器在所有融合区域均显示I级至III级异物反应，但只有2只动物在使用聚合物-磷酸钙复合椎间融合器时发生I级异物反应。12周后，生物可吸收聚（L-丙交酯-co-D，L-丙交酯）椎间融合器与三皮质骨移植物之间无显著差异。与三皮质骨移植物相比，生物可吸收聚合物-磷酸钙复合椎间融合器显示出显著更好的牵引性能、显著更高的生物力学刚度和先进的椎间融合;然而，8个聚合物-磷酸钙复合椎间融合器中有6个破裂。尽管目前尚不清楚两种生物可吸收融合器的异物反应和裂缝的结局，但与聚（L-丙交酯-共-D，L-丙交酯）融合器使用相关的早期大面积骨质溶解的出现使人们对这种生物可吸收植入物的价值产生怀疑。
Study Design. An experimental study using a sheep cervical spine interbody fusion model.Objectives. To compare interbody fusion of an autologous tricortical iliac crest bone graft with two bioabsorbable cages and to determine whether there are differences between the three interbody fusion techniques in 1) the ability to preserve postoperative distraction, 2) the biomechanical stability, and 3) the histologic characteristics of intervertebral bone matrix formation.Summary and Background Data. Bioabsorbable cages would be beneficial compared with metallic cages; however, currently no suitable bioabsorbable interbody fusion cage is available.Method. Twenty-four sheep underwent C3/C4 discectomy and fusion. The following stabilization techniques were used: Group 1) autologous tricortical iliac crest bone graft (n=8); Group 2) bioabsorbable cage made of 70/30 poly(L-lactide-co-D, L-lactide) (experimental) filled with autologous cancellous bone graft (n=8); Group 3) bioabsorbable cage made of a polymer-calciumphosphate composite (Biomet Europe, Dordrecht, The Netherlands) filled with autologous cancellous bone graft (n=8). Radiographic scans to determine disc space height were performed before and after surgery and after 1, 2, 4, 8, and 12 weeks, respectively. After 12 weeks, animals were killed, and fusion sites were evaluated using functional radiographic views in flexion and extension. Quantitative computed tomographic scans were used to assess bone mineral density, bone mineral content, and bony callus volume. Biomechanical testing was performed in flexion, extension, axial rotation, and lateral bending to determine stiffness, ROM, and neutral and elastic zone. Histomorphological and histomorphometrical analysis were performed to evaluate fusion and foreign body reactions associated with the bioabsorbable cages.Results. Over a 12-week period, the polymer-calciumphosphate composite cage showed significantly higher values for disc space height compared with the bone graft and the poly(L-lactide-co-D, L-lactide) cage. Additionally, the polymer-calciumphosphate composite cage demonstrated a significantly higher stiffness and lower ROM, neutral zone, and elastic zone in axial rotation and lateral bending than any other group. However, quantitative computed tomographic scans demonstrated cracks in six of the eight polymer-calciumphosphate composite cages after 12 weeks. Histologically, the highest bone volume/total volume ratio and the highest fusion rate were found in the polymer-calciumphosphate composite cage group. Although the poly(L-lactide-co-D, L-lactide) cage showed grade I through III foreign body reactions in all fusion areas, only two animals developed grade I foreign body reactions with the polymer-calciumphosphate composite cage.Conclusion. After 12 weeks, there was no significant difference between the bioabsorbable poly(L-lactide-co-D, L-lactide) cage and the tricortical bone graft. In comparison to the tricortical bone graft, the bioabsorbable polymer-calciumphosphate composite cage showed significantly better distractive properties, a significantly higher biomechanical stiffness, and an advanced interbody fusion; however, six of eight polymer-calciumphosphate composite cages cracked. Although the fate of the foreign body reactions and the cracks is currently unclear for both bioabsorbable cages, the early appearance of large osteolysis associated with use of the poly(L-lactide-co-D, L-lactide) cage allows skepticism regarding the value of this bioabsorbable implant.