Au A G, Aiyangar A K, Anderson P A, Ploeg H-L
Department of Mechanical Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
Proc Inst Mech Eng H. 2011 Oct;225(10):972-85. doi: 10.1177/0954411911415198.
Bone surrogates are proposed alternatives to human cadaveric vertebrae for assessing interbody device subsidence. A synthetic vertebra with representations of cortices, endplates and cancellous bone was recently developed as an alternative surrogate to polyurethane foam blocks. The ability of the two surrogates to replicate subsidence has not been fully assessed, and was evaluated by indenting them with ring-shaped indenters and comparing their performance with human cadaveric vertebrae using qualitative characteristics and indentation metrics. The sensitivity of each surrogate to a centrally or peripherally placed indenter was of particular interest. Many indentation characteristics of the foam blocks were similar to those of human cadaveric vertebrae, except their insensitivity to centrally and peripherally placed indenters, owing to their homogeneous mechanical properties. This is distinctly different from the cadaveric vertebrae, where a peripherally placed indenter indented significantly less than a centrally placed indenter, because of endplates. By contrast, the synthetic vertebra was sensitive to peripherally placed indenters owing to its bi-material composition, including a thickened peripheral endplate. However, an overly strong synthetic endplate resulted in unrepresentative indentation shape and depth. Both surrogates produced similar results to human cadaveric vertebrae in certain respects, but neither is accurate enough in terms of material property distribution to model subsidence completely in human cadaveric vertebrae.
骨替代物被提议作为人体尸体椎骨的替代品，用于评估椎间融合器的下沉情况。最近开发了一种具有皮质、终板和松质骨特征的合成椎骨，作为聚氨酯泡沫块的替代物。这两种替代物复制下沉的能力尚未得到充分评估，通过用环形压头对它们进行压痕试验，并使用定性特征和压痕指标将它们的性能与人体尸体椎骨进行比较来进行评估。特别关注的是每种替代物对中心或周边放置的压头的敏感性。泡沫块的许多压痕特征与人体尸体椎骨相似，只是由于其均匀的力学性能，它们对中心和周边放置的压头不敏感。这与尸体椎骨明显不同，在尸体椎骨中，由于终板的原因，周边放置的压头的压痕明显小于中心放置的压头。相比之下，合成椎骨由于其双材料组成，包括加厚的周边终板，对周边放置的压头敏感。然而，合成终板过强导致压痕形状和深度不具代表性。两种替代物在某些方面都产生了与人体尸体椎骨相似的结果，但就材料特性分布而言，两者都不够精确，无法完全模拟人体尸体椎骨的下沉情况。
