Then C, Menger J, Vogl T J, Hübner F, Silber G
Center of Biomedical Engineering (CBME), Frankfurt/M, Germany.
Technol Health Care. 2009;17(5-6):393-401. doi: 10.3233/THC-2009-0560.
Finite element (FE) simulations of mechanical tissue loading help provide insight into internal tissue stress and strain distribution. Thus, better understanding of pressure sore aetiology and pressure sore prophylaxis can be acquired. Indispensable in the simulation process is adequate mechanical description of interacting soft tissue and body support materials. Sufficient verification of employed material parameters is required.
Gluteal soft tissue material parameters, previously derived from experimental tissue indentation of a geometrically limited buttock sub-domain are shown to be suitable in simulating complex deformation of the entire buttocks. In the context of parameter verification, defined tissue loading via a soft foam material specimen was performed. Making use of magnetic resonance imaging (MRI), the scenario was scanned to gain tissue displacement information. Anatomical surface data was reconstructed and an FE-model of the experimental situation was generated and simulated. MR-image information was compared with simulation results.
Deformation of gluteal skin/fat and passive muscle tissue and support material under loading was in good agreement with the corresponding MR-image data. Visual accordance was found for deformed skin boundary as well as for internal fat-muscle tissue boundaries by superimposing experimental and numerical output. In addition, section surface boundaries of the MR-images and the FE-model of skin/fat and muscle at the deformed state were discretized and sufficient sample points were provided. A correlation factor of R2= 0.998 for skin/fat deformation was derived, comparing simulation with MRI output.
Reliability of employed tissue material parameters for use in realistic loading scenarios at finite strains including complex tissue and bone anatomy, non-linear tissue support material, multiple tissue types and contact interactions is shown.
机械组织负荷的有限元（FE）模拟有助于深入了解内部组织的应力和应变分布。因此，可以更好地理解压疮病因和压疮预防。在模拟过程中，对相互作用的软组织和身体支撑材料进行充分的力学描述是必不可少的。需要对所采用的材料参数进行充分验证。
先前从几何形状有限的臀部子区域的实验组织压痕中得出的臀软组织材料参数，被证明适用于模拟整个臀部的复杂变形。在参数验证的背景下，通过软泡沫材料样本进行了定义的组织负荷实验。利用磁共振成像（MRI）对该场景进行扫描，以获取组织位移信息。重建了解剖表面数据，并生成和模拟了实验情况的有限元模型。将磁共振图像信息与模拟结果进行了比较。
加载下臀皮肤/脂肪、被动肌肉组织和支撑材料的变形与相应的磁共振图像数据吻合良好。通过叠加实验和数值输出，发现变形皮肤边界以及内部脂肪-肌肉组织边界在视觉上是一致的。此外，对变形状态下的磁共振图像和皮肤/脂肪及肌肉的有限元模型的截面边界进行了离散化，并提供了足够的采样点。将模拟结果与磁共振成像输出进行比较，得出皮肤/脂肪变形的相关系数R2 = 0.998。
结果表明，所采用的组织材料参数在包括复杂组织和骨骼解剖结构、非线性组织支撑材料、多种组织类型和接触相互作用的有限应变实际加载场景中具有可靠性。
