Orthopaedic Bioengineering Research Laboratory, Department of Mechanical Engineering, Colorado State University, Fort Collins, CO 80523, USA.
Spine J. 2011 Sep;11(9):876-83. doi: 10.1016/j.spinee.2011.06.016. Epub 2011 Jul 20.
Containment plates are often placed anteriorly in anterior cervical discectomy and fusion (ACDF) to provide stability and prevent migration of the interbody device or autograft. The main advantage of a bioresorbable plate over the typical metallic plate is that it will resorb after fusion has occurred, thus mitigating any long-term instrumentation-related complications. Furthermore, the plates are radiolucent, allowing complete visualization of the fusion site and eliminating imaging artifact.
To evaluate radiographic fusion, mechanical success rates, and histologic characteristics of a bioresorbable containment plate and screws in a 3-month ovine model of ACDF.
An in vivo prospective analysis of resorbable anterior cervical plates and screws for use in ACDF in an ovine model.
Six sheep underwent C2-C3 and C4-C5 discectomies. Fusions were performed using a polyetheretherketone cage filled with autograft bone. A polymeric plate (70/30 poly-dl-lactic acid), and four screws were placed over an intervertebral disc spacer at each of these two levels. After 3 months, the animals were euthanized and radiographically imaged. Radiographs were analyzed for fusion and instrumentation failures. Functional spinal units were harvested for histologic processing and evaluation.
Radiographic fusion was noted in three of the 12 levels with no evidence of device failure at any of the levels. However, at necropsy, it was observed that six of the 12 specimens had either a broken screw or a cracked plate. These gross observations were confirmed within the histologic sections. Fusion was verified histologically at C2-C3 in three of the six sheep; none of the fusions were successful at C4-C5. Histologic analysis also found that the tissue surrounding the plate and disc spacer consisted of vascularized fibrous tissue with islands of active woven bone. Inflammatory cells were rarely observed.
Although the bioresorbable plates and screws did not elicit an iatrogenic tissue response, a high percentage of them failed mechanically. This phenomenon was difficult to observe radiographically, as the radiolucent markers were not able to convey these instrumentation failures. Additionally, there was only a 25% fusion rate. These findings suggest that resorbable implant materials with the current biomechanical and chemical properties are inadequate for cervical fusion. The results of this study strongly suggest that radiographic outcomes alone may not be adequate and that gross or histologic methods should accompany radiographs in studies of bioresorbable materials in animal models.
在颈椎前路椎间盘切除融合术（ACDF）中，通常在前部放置固定盘以提供稳定性并防止椎间设备或移植物的迁移。与典型的金属板相比，生物可吸收板的主要优势在于，它在融合发生后会被吸收，从而减轻任何与长期器械相关的并发症。此外，这些板是半透明的，可以完全观察到融合部位，并消除成像伪影。
在羊颈椎前路椎间盘切除融合术的 3 个月模型中，评估生物可吸收固定盘和螺钉的影像学融合、机械成功率和组织学特征。
羊模型中使用生物可吸收颈椎前路板和螺钉进行颈椎前路椎间盘切除融合术的体内前瞻性分析。
六只羊接受了 C2-C3 和 C4-C5 椎间盘切除术。融合采用聚醚醚酮（PEEK）笼填充自体骨进行。在这两个节段的每个节段上，都放置了一个聚合物板（70/30 聚-dl-乳酸）和四个螺钉。3 个月后，处死动物并进行影像学检查。对影像学融合和器械失败进行分析。对功能脊柱单位进行组织学处理和评估。
在 12 个节段中的 3 个节段中观察到影像学融合，在任何节段都没有设备失败的证据。然而，在尸检中，观察到 12 个标本中的 6 个出现了螺钉断裂或板开裂。这些大体观察结果在组织学切片中得到了证实。在 6 只羊中的 3 只 C2-C3 处，融合在组织学上得到了验证；而 C4-C5 处没有一个融合成功。组织学分析还发现，板和椎间盘间隔物周围的组织由血管化纤维组织和活跃的编织骨岛组成。很少观察到炎症细胞。
尽管生物可吸收板和螺钉没有引起医源性组织反应，但它们的机械失效比例很高。这种现象很难通过影像学观察到，因为半透明的标记物无法传达这些器械失败。此外，融合率仅为 25%。这些发现表明，具有当前生物力学和化学性能的可吸收植入物材料不足以进行颈椎融合。本研究结果强烈表明，单独的影像学结果可能不够充分，在动物模型中研究可吸收材料时，应结合影像学检查使用大体或组织学方法。
