计算机辅助股骨近段髓腔结构三维重建及个体化股骨假体设计

Computer Assisted Restruction of Three Dimensional Canal Model of Femur and Design of Custom Made Stem

目的 研制开发一套切合实际、经济实用、使用方便的计算机辅助设计制造 (CAD/CAM )软件系统 ,在现有条件下 ,完成CAD/CAM个体化假体的设计。方法 取成人尸体股骨做上段的CT断层扫描 ,得到CT数据的二维图像 ;将所得的二维图像输入计算机。用开发的两套软件对二维图像进行处理 ,识别髓腔内轮廓 ;重建髓腔结构模型 ,提取髓腔轮廓及假体轮廓数据 ;利用CAD软件设计假体 ,并模拟植入过程。结果 股骨上段小粗隆以上部分结构复杂 ,需计算机自动识别和人工识别相结合 ,才能拾取有利于假体设计的轮廓曲线 ,小粗隆以下部分拾取边缘清晰 ,曲线完整。重建的三维髓腔结构重现其生理弯曲及基本形态。设计的假体符合髓腔结构并可植入髓腔内。结论 以CT二维图像为依据 ,采用CAD/CAM系统 ,在现有的条件下 ,可设计出良好匹配的个体化假体 ,完全可以用于临床。

Objective To develop a computer assisted design and manufacturing system for custom made stems.Methods Using 1 human cadaer femur,computed tomography(CT) scans was taken prepare a series of 3 0 mm thick cross section slices.CT scan digitized images were transmitted to a computer.The two software program developed obained inner bone contours,and restructured these contours in the metaphyzeal;then the three dimensional canal model was rendered.The design software generated a three dimensional stem shape that provided optimal implant bone fit and was surgically insertable.Results The inner bone contours was clear and scientive in the lower lesser trochanter,but complex and noscientive in the uper lesser trochanter which be infrent by man.The rendering three dimensional canal model have a lateral's' shaped curvature.The lateral S shaped curvature of the femoral canal made it impossible to insert the exact-stem.They had to be modified to make femoral insertion and extraction possible.The optimal design custom stem could be inserted into the modular canal.Conclusion The CAD/CAM custom made femoral stem that had optoimal implant bone fit proved the maximum stem contact on the internal cortical bone surface.