Department of Mechanical Engineering, University of California, Berkeley, CA.
Scalable Solvers Group, Lawrence Berkeley National Lab, Berkeley, CA.
Spine (Phila Pa 1976). 2021 Oct 1;46(19):E1022-E1030. doi: 10.1097/BRS.0000000000004023.
Micro-computed tomography- (micro-CT-) based finite element analysis of cadaveric human lumbar vertebrae virtually implanted with total disc arthroplasty (TDA) implants.
(1) Assess the relationship between vertebral porosity and maximum levels of bone-tissue stress following TDA; (2) determine whether the implant's loading mode (axial compression vs. sagittal bending) alters the relationship between vertebral porosity and bone-tissue stress.
Implant subsidence may be related to the bone biomechanics in the underlying vertebral body, which are poorly understood. For example, it remains unclear how the stresses that develop in the supporting bone tissue depend on the implant's loading mode or on typical inter-individual variations in vertebral morphology.
Data from micro-CT scans from 12 human lumbar vertebrae (8 males, 4 females; 51-89 years of age; bone volume fraction [BV/TV] = 0.060-0.145) were used to construct high-resolution finite element models (37 μm element edge length) comprising disc-vertebra-implant motion segments. Implants were loaded to 800 N of force in axial compression, flexion-, and extension-induced impingement. For comparison, the same net loads were applied via an intact disc without an implant. Linear regression was used to assess the relationship between BV/TV, loading mode, and the specimen-specific change in stress caused by implantation.
The increase in maximum bone-tissue stress caused by implantation depended on loading mode (P < 0.001), increasing more in bending-induced impingement than axial compression (for the same applied force). The change in maximum stress was significantly associated with BV/TV (P = 0.002): higher porosity vertebrae experienced a disproportionate increase in stress compared with lower porosity vertebrae. There was a significant interaction between loading mode and BV/TV (P = 0.002), indicating that loading mode altered the relationship between BV/TV and the change in maximum bone-tissue stress.
Typically-sized TDA implants disproportionately increase the bone-tissue stress in more porous vertebrae; this affect is accentuated when the implant impinges in sagittal bending.Level of Evidence: N/A.
对虚拟植入全椎间盘置换（TDA）假体的尸体人腰椎进行微计算机断层扫描（micro-CT）的有限元分析。
（1）评估 TDA 后椎体孔隙率与骨组织最大应力度之间的关系；（2）确定假体的加载模式（轴向压缩与矢状弯曲）是否改变了椎体孔隙率与骨组织应力度之间的关系。
假体下沉可能与支撑骨内的骨生物力学有关，但这方面的知识还很欠缺。例如，支撑骨组织内产生的应力如何取决于假体的加载模式，或者取决于个体间椎体形态的典型差异，这些都还不清楚。
使用来自 12 个人体腰椎（8 名男性，4 名女性；51-89 岁；骨体积分数[BV/TV]为 0.060-0.145）的 micro-CT 扫描数据，构建高分辨率有限元模型（37μm 单元边长），包含椎间盘-椎体-假体运动节段。假体在轴向压缩、屈曲和伸展引起的撞击下加载 800N 的力。为了比较，在没有假体的情况下，同样的净负荷通过完整的椎间盘施加。线性回归用于评估 BV/TV、加载模式和植入引起的标本特异性应力变化之间的关系。
植入引起的最大骨组织应力增加取决于加载模式（P<0.001），在弯曲引起的撞击中比轴向压缩时增加更多（对于相同的施加力）。最大应力的变化与 BV/TV 显著相关（P=0.002）：与低孔隙率椎体相比，孔隙率较高的椎体经历了不成比例的应力增加。加载模式与 BV/TV 之间存在显著的相互作用（P=0.002），表明加载模式改变了 BV/TV 与最大骨组织应力变化之间的关系。
通常大小的 TDA 假体不成比例地增加了更多孔椎体的骨组织应力；当假体在矢状弯曲中撞击时，这种影响会更加明显。
N/A。
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