人工髋关节活体有限元建模及力学分析

In vivo finite element modeling and mechanical analysis of artificial hip joint

背景:有限元分析最为广泛地应用于人工髋关节置换的研究,能够反映人工髋关节置换前后的应力分布情况。目的:通过CT扫描图像建立人工髋关节置换后的三维有限元模型,分析假体和股骨的力学分布,提供研究活体内假体的评估方法。方法:选非水泥型人工髋关节假体置换后患者1例,64排CT扫描髋关节,通过三维建模软件建立三维有限元模型,加载载荷1500N,分析假体和股骨的应力分布,并与体外建模和正常股骨有限元模型比较。结果与结论:应用患者人工髋关节置换后CT扫描图像建立的三维有限元模型,加载后应力主要分布在股骨干上端1/3处,在股骨假体柄颈结合处,假体外侧,假体的远端与股骨接触处,是假体置换后应力在体内传递的真实反映。结果说明活体髋关节建模优于体外建模,不改变假体在体内的位置,人工髋关节活体建模是假体评估新方法。

BACKGROUND： Finite element analysis has been widely used for the study of human＇s hip replacement. It is a usefu method to demonstrate the stress distribution before or after hip replacement. OBJECTIVE： To analyze the mechanical distribution of the prosthesis and the femur by the three-dimension finite element model after hip replacement based on the CT scanning image, in order to provide the method for the evaluation of femoral prosthesis in vivo. METHODS： One patient with uncemented prosthesis replacement has been scanned with 64-slice CT. With the help of three-dimensional modeling software, a three-dimensional finite element model of femur was established. 1 500 N was loaded on the femoral head prosthesis, and the stress distribution of the prosthesis and the femur was analyzed, and then compared with the in vitro model and finite element model of the normal femur. RESULTS AND CONCLUSION： The three-dimensional finite element model has been established using the CT scanning images after the total hip arthroplasty. After loading force on the model, we found that the stress mainly distributed on the 1/3 superior part of femur, on the prosthesis where neck and stem integrated, lateral of the stem and the area contact with prosthesis distal end, and that was the true reaction for the stress distribution after replacement. It indicates that in vivo hip joint modeling is superior to in vitro modeling; in vivo modeling of artificial hip prosthesis is a new method to evaluate the prosthesis without changing the position of the prosthesis.