个体化人工半膝关节假体计算机辅助设计和快速成型的基础:股骨髁三维建模(英文)

Computer-aided design and rapid prototyping technique for individualized artificial semi-knee joint prosthesis:Establishment of three-dimensional model of femoral condyle

背景:目前保肢方法有异体骨关节置换、人工金属假体置换、肿瘤骨段灭活再植等,各有优缺点。四肢骨肿瘤切除深低温冷冻大段异体骨关节置换术存在异体-自体关节不匹配和后期关节软骨坏死影响关节功能的问题。目的:评估一种由螺旋CT扫描数据获取关节软骨表面轮廓信息的方法,为基于快速成型技术的个体化人工半膝关节研究奠定基础。设计:开放性实验。单位:解放军兰州军区乌鲁木齐总医院创伤一科。材料:实验于2001-09/2003-05在解放军第四军医大学西京医院骨科研究所和西安交通大学先进制造研究所完成。样本来源:CT扫描对象为25岁健康男性志愿者。方法:采用Picker6000螺旋CT对股骨远端进行层厚1mm扫描,在Picker6000CT机的VoxelQ图像工作站进行三维容积重建,之后对重建数据间隔0.1mm下载二维断层图像。自行开发数据格式转换软件,对下载图像进行滤波、去噪等处理,求出断面图像的二维边缘轮廓矢量化数据,输入美国Imageware公司Surfacer9.0软件进行矢量化三维重建。然后通过对关节软骨轮廓的识别及假体设计需要,提取出感兴趣的关节软骨表面轮廓的三维图像,用于个体化人工半膝关节的计算机辅助设计。主要观察指标:CT图像的矢量转换和股骨髁三维重建矢量图像。结果:利用自主开发的医学图像矢量转换软件,实现了CT图像数据的矢量转换,在Surfacer9.0三维处理软件中构建出个体化股骨髁三维实体模型,并根据设计需要进行编辑,提取出可进行人工半膝关节假体计算机辅助设计需要的关节软骨三维模型。所构关节面轮廓可进一步处理,从而完成人工半膝关节假体的计算机辅助设计;其文件格式为.stl格式,可直接被快速成形软件识别和用于工程学制造。结论:由螺旋CT数据进行关节软骨外形轮廓的矢量化重建可获得精确的关节软骨轮廓三维实体模型,模型可编辑性强,为复合大段异体骨移植的人工半膝关节假体的计算机辅助设计和快速成型制造打下了基础;用此方法进行医学图像信息的矢量转换简单易行,在骨科、口腔颌面外科生物制造领域有良好的应用前景。

BACKGROUND：At present, there are several limb-preserving methods, such as xenogenic bone joint replacement, artificial metal prothosis replacement and inactivation and replantation of tumor bone segment, etc. Each method has its advantages and disadvantages. In addition, mismatch of xenogenic and autogeneic joints and articular cartilage necrosis in the late stage, which affects joint function, are .two important problems for large frozen bone-joint allagraft at ultra-low temperature in repair of bone defect following bone tumor resections in extremities. OBJECTIVE：To evaluate a method to obtain.outline information on the cartilage surface through spiral CT scanning data, so as to lay foundation for study on individualized attifical semi,knee joint based on rapid pintotyping （RP） technique. DESIGN： Open experiment. SETTING： First Department of Trauma, Urumqi General Hospital of Lanzhou Military Area Command of Chinese PLA. MATERIALS： This experiment was carried out at Institute of Orthopaedics, Xijing Hospital, Fourth Military Medical University of Chinese METHODS：Distal femur was performed 1 nun in thickness scanning with Picker 6 000 spiral CT. Three-dimensional volume reconstruction was conductod at the Voxel Q Image workstation on Picker 6000 CT; then, two-dimensional tomography image of reconstruetion data were downloaded with spacing of 0.1 mm. Data format converter software was self-developed. The downloaded image was treated through smoothing, de-noise and so on. Vector data of two-dimensional borderline outline of tomogmphy image was calculated and input into Surfacer 9.0 software （American Imageware compatty） for vectorial three-dimensional reconstruction. According to recognition of articular cartilage outline and request of prothesis design, the threedimensional images of interested articular cartilage surface outline were extracted and used in the computer-aided design for individualized artificial semi-knee joint. MAIN OUTCOME MEASURES：Vector converting of CT image and vector image of three-dimensional reconstruction of femoral condyle. RESULTS：Vector converting of CT image data had been come true using self-developed medical image vector converter software. Three-dimensional solid model of individualized femoral condyle .as constructed with Surfacer9.0 three-dimensional processing software and edited according to design request. Three-dimensional model of articular cartilage requested by artifical semi-knee joint prothosis was extracted for computer-aided design. The constructed articular surface outline could be treated further to complete computer-aided design of artificial semi-knee joint prothesis; The file for-mat was .stl, which could he recognized by RP software and used in engineering. CONCLUSION：Vector reconstruction of articular cartilage outline is performed based on spiral CT data that can obtain precise three-dimensional solid model of articular cartilage outline. The three-dimensional model can he edited, which lays foundation for computer-aidod design and RP manufacturing of artificial semi-knee joint prothesis compounded with large segment xenogenic bone; It is easy and practicable in vector converting of medical image information with this method, and it also has good application prospect in biomanufactufing field in orthopaedic and oral maxillofacial surgery.