Department of Mechanical & Mechatronics Engineering, University of Waterloo, Waterloo, ON, Canada.
J Mech Behav Biomed Mater. 2024 Nov;159:106679. doi: 10.1016/j.jmbbm.2024.106679. Epub 2024 Aug 3.
Implant subsidence into the underlying trabecular bone is a common problem in orthopaedic surgeries; however, the ability to pre-operatively predict implant subsidence remains limited. Current state-of-the-art computational models for predicting subsidence have issues addressing this clinical problem, often resulting from the size and complexity of existing subject-specific, image-based finite element (FE) models. The current study aimed to develop a simplified approach to FE modeling of subject-specific trabecular bone indentation resulting from implant penetration. Confined indentation experiments of human trabecular bone with flat- and sharp-tip indenters were simulated using FE analysis. A generalized continuum-level approach using a meshless smoothed particle hydrodynamics (SPH) approach and an isotropic crushable foam (CF) material model was developed for the trabecular bone specimens. Five FE models were generated with CF material parameters calibrated to cadaveric specimens spanning a range of bone mineral densities (BMD). Additionally, an alternative model configuration was developed that included consideration of bone marrow, with bone and marrow material parameters assigned to elements randomly according to bone volume (BV%) measurements of experimental specimens, owing to the non-uniform nature of trabecular bone tissue microstructure. Statistical analysis found significant correlation between the shapes of the numerical and experimental force-displacement curves. FE models accurately captured the bone densification patterns observed experimentally. Inclusion of marrow elements offered improved response prediction of the flat-tip indenter tests. Ultimately, the developed approach demonstrates the ability of a generalizable continuum-level SPH approach to capture bone variability using clinical bone imaging metrics without needing detailed image-based geometries, a significant step towards simplified subject-specific modeling of implant subsidence.
种植体下沉到骨小梁中是骨科手术中的一个常见问题；然而，术前预测种植体下沉的能力仍然有限。目前用于预测下沉的最先进的计算模型在解决这个临床问题时存在一些问题，这通常是由于现有的基于图像的特定于主体的有限元 (FE) 模型的大小和复杂性造成的。本研究旨在开发一种简化的方法来模拟植入物穿透引起的特定于主体的骨小梁压痕的 FE 模型。使用 FE 分析模拟了具有平面和尖锐压头的人骨小梁的受限压痕实验。针对骨小梁标本，开发了一种基于无网格平滑粒子流体动力学 (SPH) 方法和各向同性可压缩泡沫 (CF) 材料模型的广义连续体级方法。使用针对尸体标本的 CF 材料参数生成了五个 FE 模型，这些尸体标本的骨矿物质密度 (BMD) 范围较广。此外，还开发了一种替代模型配置，其中包括考虑骨髓，根据实验标本的骨体积 (BV%) 测量值，将骨髓和骨髓材料参数随机分配给元素，由于骨小梁组织微结构的非均匀性。统计分析发现，数值和实验力-位移曲线的形状之间存在显著相关性。FE 模型准确地捕捉到了实验中观察到的骨致密化模式。包含骨髓元素可以提高平面压头试验的响应预测。最终，所开发的方法展示了通用连续体级 SPH 方法使用临床骨成像指标捕捉骨变异性的能力，而无需详细的基于图像的几何形状，这是简化植入物下沉特定于主体建模的重要一步。
