Present paper aims to contribute to the definition of an effective strategy for the quantification of fracture risk in metastatic femurs, by means of a finite-element (FE) computational approach based on a refined constitutive description of the bone tissue. Healthy bone and metastatic tissue are described by a linearly poroelastic approach, by accounting for the specific degradation of material properties in the metastatic regions as related to the computed tomography (CT) evidence. The bone-metastasis interaction is also modelled through a Gaussian-shaped graded transition of material properties for the bone around the metastasis. Fracture risk indications are furnished by defining a strain-based local index and by referring to local patterns of strain energy density. Proposed computational strategy is applied to a clinical case related to a patient with both femurs affected by multiple metastases. Subject-specific FE 3D models of right and left femurs are generated from CT images and their mechanical responses are simulated by addressing a functional compressive load. Comparisons with a standard linearly elastic formulation (EL), that simply models the metastases as a pseudo-healthy tissue with low levels of material density and stiffness, are performed. Proposed results highlight that the adopted refined constitutive description identifies higher fracture risk levels with respect to the EL formulation, resulting also in very different patterns of bone regions prone to failure. In the limit of a suitable calibration based on significant experimental evidence, the proposed strategy may improve the strength prediction in metastatic femurs, allowing for an effective assessment of fracture risk useful in clinical practice.

中文翻译：

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转移性股骨骨折风险评估：基于患者特定 CT 的有限元方法

本论文旨在通过基于骨组织精细本构描述的有限元 (FE) 计算方法，为量化转移性股骨骨折风险的有效策略的定义做出贡献。通过考虑与计算机断层扫描 (CT) 证据相关的转移区域中材料特性的特定退化，通过线性多孔弹性方法描述健康的骨骼和转移组织。骨转移相互作用也通过转移周围骨的材料特性的高斯形渐变过渡进行建模。通过定义基于应变的局部指数和参考应变能量密度的局部模式来提供骨折风险指示。建议的计算策略应用于与双股骨受多发转移影响的患者相关的临床病例。右股骨和左股骨的特定对象 FE 3D 模型是从 CT 图像生成的，它们的机械响应通过解决功能性压缩负载来模拟。与标准线性弹性公式 (EL) 进行了比较，该公式将转移灶简单地建模为具有低水平材料密度和刚度的假健康组织。提议的结果强调，采用的精炼本构描述确定了与 EL 公式相关的更高骨折风险水平，这也导致了容易发生故障的骨骼区域模式非常不同。在基于重要实验证据的适当校准的限制下，