Institute for Biomechanics, ETH Zurich, Zurich, Switzerland.
Biomech Model Mechanobiol. 2012 Mar;11(3-4):313-23. doi: 10.1007/s10237-011-0312-4. Epub 2011 May 12.
The determining factors for the fixation of uncemented screws in bone are the bone-implant interface and the peri-implant bone. The goal of this work was to explore the role of the peri-implant bone architecture on the mechanics of the bone-implant system. In particular, the specific aims of the study were to investigate: (i) the impact of the different architectural parameters, (ii) the effects of disorder, and (iii) the deformations in the peri-implant region. A three-dimensional beam lattice model to describe trabecular bone was developed. Various microstructural features of the lattice were varied in a systematic way. Implant pull-out tests were simulated, and the stiffness and strength of the bone-implant system were computed. The results indicated that the strongest decrease in pull-out strength was obtained by trabecular thinning, whereas pull-out stiffness was mostly affected by trabecular removal. These findings could be explained by investigating the peri-implant deformation field. For small implant displacements, a large amount of trabeculae in the peri-implant region were involved in the load transfer from implant to bone. Therefore, trabecular removal in this region had a strong negative effect on pull-out stiffness. Conversely, at higher displacements, deformations mainly localized in the trabeculae in contact with the implant; hence, thinning those trabeculae produced the strongest decrease in the strength of the system. Although idealized, the current approach is helpful for a mechanical understanding of the role played by peri-implant bone.
未固定螺钉在骨中的固定的决定因素是骨-植入物界面和植入物周围的骨。这项工作的目的是探讨植入物周围骨结构对骨-植入物系统力学的作用。具体来说，本研究的具体目的是研究：（i）不同结构参数的影响，（ii）无序的影响，和（iii）植入物周围区域的变形。开发了一个用于描述小梁骨的三维梁格模型。梁格的各种微观结构特征以系统的方式变化。模拟了植入物拔出试验，并计算了骨-植入物系统的刚度和强度。结果表明，小梁变薄导致拔出强度的最强下降，而拔出刚度主要受小梁去除的影响。通过研究植入物周围的变形场可以解释这些发现。对于小的植入物位移，植入物周围区域的大量小梁参与了从植入物到骨的载荷传递。因此，该区域的小梁去除对拔出刚度有很强的负面影响。相反，在较高的位移下，变形主要局限于与植入物接触的小梁；因此，变薄这些小梁会导致系统强度的最强下降。尽管目前的方法是理想化的，但它有助于机械理解植入物周围骨所起的作用。
