Wen-ming Xi, Ai-min Wang, Qi Wu, Chang-hua Liu, Jian-fei Zhu, Fang-fang Xia
School of Physics and Mechanical Engineering, Xiamen University, Xiamen 361005, China.
School of Physics and Mechanical Engineering, Xiamen University, Xiamen 361005, China.
Med Eng Phys. 2015 Sep;37(9):911-5. doi: 10.1016/j.medengphy.2015.06.005. Epub 2015 Jul 22.
Aseptic loosening is the primary cause of cementless femoral prosthesis failure and is related to the primary stability of the cementless femoral prosthesis in the femoral cavity. The primary stability affects both the osseointegration and the long-term stability of cementless femoral prostheses. A custom cementless femoral prosthesis can improve the fit and fill of the prosthesis in the femoral cavity and decrease the micromotion of the proximal prosthesis such that the primary stability of the custom prosthesis can be improved, and osseointegration of the proximal prosthesis is achieved. These results will help to achieve long-term stability in total hip arthroplasty (THA). In this paper, we introduce an integrated CAD/CAM/robotic method of milling custom cementless femoral prostheses. The 3D reconstruction model uses femoral CT images and 3D design software to design a CAD model of the custom prosthesis. After the transformation matrices between two units of the robotic system are calibrated, consistency between the CAM software and the robotic system can be achieved, and errors in the robotic milling can be limited. According to the CAD model of the custom prosthesis, the positions of the robotic tool points are produced by the CAM software of the CNC machine. The normal vector of the three adjacent robotic tool point positions determines the pose of the robotic tool point. In conclusion, the fit rate of custom pig femur stems in the femoral cavities was 90.84%. After custom femoral prostheses were inserted into the femoral cavities, the maximum gaps between the prostheses and the cavities measured less than 1 mm at the diaphysis and 1.3 mm at the metaphysis.
无菌性松动是无骨水泥型股骨假体失败的主要原因，且与无骨水泥型股骨假体在股骨髓腔内的初始稳定性有关。初始稳定性影响无骨水泥型股骨假体的骨整合及长期稳定性。定制的无骨水泥型股骨假体可改善假体在股骨髓腔内的贴合度与填充情况，并减少近端假体的微动，从而提高定制假体的初始稳定性，实现近端假体的骨整合。这些结果将有助于在全髋关节置换术（THA）中实现长期稳定性。在本文中，我们介绍一种用于铣削定制无骨水泥型股骨假体的集成CAD/CAM/机器人方法。三维重建模型利用股骨CT图像和三维设计软件来设计定制假体的CAD模型。在对机器人系统的两个单元之间的变换矩阵进行校准后，可实现CAM软件与机器人系统之间的一致性，并限制机器人铣削中的误差。根据定制假体的CAD模型，由数控机床的CAM软件生成机器人刀具点的位置。三个相邻机器人刀具点位置的法向量决定机器人刀具点的姿态。总之，定制猪股骨柄在股骨髓腔内的贴合率为90.84%。将定制股骨假体插入股骨髓腔后，假体与髓腔之间在骨干处的最大间隙小于1毫米，在干骺端处小于1.3毫米。
