Jia Zhongyu, Yang Daiyun, Wang Yue, Zhu Xiangdong, Feng Yu, Wang Yitian, Wu Bi
School of Medicine,University of Electronic Science and Technology of China, Chengdu Sichuan, 610054, P.R.China;Department of Orthopedics, the Affiliated Hospital of Electronic Science and Technology of China & Sichuan Provincial People's Hospital, Chengdu Sichuan, 610072, P.R.China.
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Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi. 2017 Jan 15;31(1):46-51. doi: 10.7507/1002-1892.201609010.
To investigate the validity of improving the femur's mechanical characteristics by implanting calcium phosphate ceramic screws after removing dynamic hip screw (DHS).
The three dimensional finite element model of the femur was built based on the CT scanning of a normal male volunteer. Then the models of the femur with and without DHS were established. According to calcium phosphate ceramic screws with porosity and apparent elastic modulus, 80% and 0.1 GPa were set as group A, 50% and 1.0 GPa as group B, and 30% and 1.5 GPa as group C. Von Mises stress distribution and maximum stress were recorded when the joint was maximally loaded in a gait cycle.
The Von Mises in normal femoral shaft was uniform; no phenomena of stress concentration was observed and the maximum stress located at the joint load-bearing site of the proximal femur. The stress concentration was observed in the femur without DHS, and the maximum stress located at the distal femur around the screw hole. By comparing several different calcium phosphate ceramic screws, the stress distribution of group B was similar to normal femur model, and the maximum stress located at the joint load-bearing site. The other screws of groups A and C showed varying degrees of stress concentration.
Implanting calcium phosphate ceramic screw can improve the mechanical characteristics of the femur after removing dynamic hip screw, and the calcium phosphate ceramic screw with 50% porosity and 1.0 GPa apparent elastic modulus is suitable for implanting.
探讨取出动力髋螺钉（DHS）后植入磷酸钙陶瓷螺钉改善股骨力学特性的有效性。
基于一名正常男性志愿者的CT扫描构建股骨三维有限元模型。然后建立有和没有DHS的股骨模型。根据孔隙率和表观弹性模量设置磷酸钙陶瓷螺钉，孔隙率80%、表观弹性模量0.1GPa设为A组，孔隙率50%、表观弹性模量1.0GPa设为B组，孔隙率30%、表观弹性模量1.5GPa设为C组。记录步态周期中关节最大负荷时的冯·米塞斯应力分布和最大应力。
正常股骨干的冯·米塞斯应力分布均匀；未观察到应力集中现象，最大应力位于股骨近端的关节承重部位。在没有DHS的股骨中观察到应力集中，最大应力位于螺钉孔周围的股骨远端。通过比较几种不同的磷酸钙陶瓷螺钉，B组的应力分布与正常股骨模型相似，最大应力位于关节承重部位。A组和C组的其他螺钉显示出不同程度的应力集中。
植入磷酸钙陶瓷螺钉可改善取出动力髋螺钉后股骨的力学特性，孔隙率50%、表观弹性模量1.0GPa的磷酸钙陶瓷螺钉适合植入。
