基于CT三维重建个体化股骨假体的计算机辅助设计

背景:由于人体的绝对个性化特点,标准人工假体与患者骨骼之间的误差使二者难以很好匹配.计算机辅助设计和制造个体化假体克服了其他假体的缺点,可有效地延长人工关节的使用寿命和使用质量,并可能解决人工关节的翻修问题.国内的研究尚处于起步阶段.目的:基于CT图像的三维重建,探求个体化股骨假体计算机辅助设计在提高假体与病变骨骼匹配度中的作用.方法:CT扫描对象为1例健康男性志愿者,排除髋关节疾患.采用GE Speed Light 16排螺旋CT对股骨中上段进行层厚3 mm扫描,得到CT数据的二维图像,利用自主开发的数据格式转换软件将CT图像转换为bmp格式.对位图编辑预处理,用Mimics8.1软件进行矢量化处理,提取股骨内外轮廓.然后输入Mimics8.1和Rapidform2004三维反求工程软件中,生成股骨内外轮廓的特征曲线,重建股骨三维模型.将股骨髓腔的特征轮廓曲线dxf文件输入计算机辅助设计建模软件Solidworks2004中,以此股骨髓腔轮廓为基础,完成个体化股骨假体的设计.结果与结论:利用自主开发的数据格式转换软件,实现了CT图像信息的矢量转换.以CT二维图像为依据,进行三维反求,可获得精确的股骨内外轮廓三维实体模型.采用反求工程与正向计算机辅助设计相结合,可设计出匹配良好的个体化股骨假体.提示反求工程和计算机辅助设计技术为个体化假体的研制提供了一个有效可行的途径,解决假体与病变骨骼的良好匹配,可防止假体松动,提高其长期稳定性.

Computer-assisted design of individualized femoral prosthesis according to 3D reconstruction of CT images

BACKGROUND: Due to individual characteristics of human body, it is difficult to well match between standard prosthesis and patient skeleton. Computer-assisted design and manufacture of individualized prosthesis can effectively prolong artificial joint lifespan and quality and reduce revision rate. However, related studies are few in China.OBJECTIVE: To explore computer-assisted design for individualized femoral head prosthesis according to three-dimensional (3D)reconstruction of CT images for improving prosthesis and affected skeleton matching.METHODS: The CT scanning image of one healthy male volunteer, with no hip joint disease, was used. His femur was scanned with GE Speed Light CT with 3.0 mm thick cross-section slices. CT 2D images were transmitted to a computer. The medical image format was translated from DICOM into bmp. Inner and external bone contours were drawn automatically or by hand and processed digitally, and then these data were downloaded into 3D Mimics8.1, and Rapidform2004 software. The 3D femoral canal model was rendered. Femur canal contours curve was downloaded into the Solidworks2004 software in the form of dxf. Femoral prosthesis was designed on the base of femoral canal contours curve.RESULTS AND CONCLUSION: The CT image was transmitted in the form of vector by a set of self-made medical image processing software. The accurate 3D femoral internal/external outline model was obtained by CT 2D image and reverse technique. Suitable femoral prosthesis was designed by means of image reverse engineering and norientation CAD. Reverse engineering and CAD provide an effective way to develop individualized prosthesis, improve the matching of prosthesis and affected skeleton, prevent prosthesis loosening and improve long-term stability.