股骨近端溶骨性转移瘤三维有限元模型的力学分析

背景：如何评估股骨近端转移瘤的骨折风险在临床上争议较多。 目的：建立股骨近端不同大小溶骨性转移瘤的三维有限元模型,分析在慢步行走过程中病变局部的应力变化,评估骨折风险。 方法：对志愿者双下肢进行薄层CT扫描获得股骨数据,图像处理软件Mimics11.1进行图像处理后数据导入建模软件UG4.0建立股骨近端3个部位溶骨性病变模型,给予加载缓慢行走时单足落地状态下股骨的载荷,利用有限元软件分析股骨颈区,转子间区及转子下区应力的变化。 结果与结论：①股骨颈水平：皮质完整的髓内缺损破坏直径至相应冠状面直径的90%局部应力突然增长至135.98 MPa,破坏一半内侧皮质的髓内病变至70%局部应力突然增长至92.34 MPa,完全破坏皮质的半球形病变至60%时,局部应力大于屈服应力,增长至101.19 MPa。②转子间水平：内侧皮质完整的髓内球形病变破坏直径至80%局部应力突然增长至131.21 MPa,破坏一半内侧皮质的髓内病变破坏至80%局部应力突然增长至105.19 MPa,完全破坏皮质的半球形病变至70%时,局部应力大于屈服应力,增长至92.21 MPa。③转子下水平：破坏一半内侧皮质的髓内病变破坏至80%局部应力突然增长至92.42 MPa,完全破坏皮质的半球形病变至70%-80%之间,局部应力增长至89.97-105.19 MPa,大于屈服应力。结果表明股骨近端未穿透骨皮质的髓内病变对股骨近端应力变化影响不大。对于破坏单侧骨皮质的病变,在股骨颈水平破坏直径大于60%时存在骨折风险,转子间水平破坏直径大于70%时存在骨折风险,转子下水平破坏直径大于70%时存在骨折风险。

Mechanical analysis of three-dimensional finite element model on the osteolytic metastases of proximal femur

BACKGROUND:There are many controversies about how to assess fracture risks of the proximal femoral metastases tumor in clinical practice. OBJECTIVE:To establish the three-dimensional finite element model of different sizes of the osteolytic metastases tumor in proximal femur, and to analyze the stress changes in the local lesion during slow walk mode and to assess the fracture risks. METHODS:Both lower extremities of the volunteers underwent thin CT scan to obtain data related to the femur. The image data were input into Mimics11.1 image processing software for image processing, then, the data were input into UG4.0 software to establish the bone lesion model of three parts of proximal femur. Then, loaded the femur when single foot landing during slow walking mode. Finally, the finite element software was used to analyze the femoral neck district, intertrochanteric area and change of stress levels in subtrochanteric zone. RESULTS AND CONCLUSION:Defects of femoral neck level: when the intramedullary defect did not involved inner cortex in diameter to 90%, the local stress abruptly increased to 135.98 MPa, while intramedullary defects involved half of medial cortex to 70%, the local stress abruptly increased to 92.34 MPa. When the hemispheric lesions with destruction of the cortex up to 60%, the local stress became greater than the yield stress, and up to 101.19 Mpa. Intertrochanteric level: when the intramedullary defect did not involved inner cortex in diameter to 80%, the local stress jumped to 131.21 MPa, while intramedullary defects involved half of medial cortex to 80%, the local stress abruptly increased to 105.19 MPa. The hemispherical lesions with destruction of the cortex defect of 80%, the local stress was greater than the yield stress scale, and up to 92.21 MPa. While intramedullary defects involved half of medial cortex to 80%, the local stress jumped to 92.42 MPa. When hemispheric lesions with destruction of the cortex increased to 70%-80%, the local stress will increased to 89.97-105.19 Mpa, and greater than the yield stress. In proximal femur, the intramedullary lesions which do not penetrate the cortical bone have little effect on stress scales in the same place. For the lesions which destroy the unilateral cortical bone, the risks would occur on such conditions as: in femoral neck level, the destruction in diameter greater more than 60%; in intertrochanteric level, the destruction in diameter greater more than 70%; in subtrochanteric level, the destruction in diameter greater more than 70%.