Femoral Three-dimensional Reconstruction And Biomechanics Characteristic Analysis Integrated With Experimental Study

In total hip replacement, due to matching with medullary cavity ,custom-made hip prosthesis can better adapt to biomechanics environment in human body, eliminate destruction for femoral normal stress, and reduce stress-shielding ,so as to advance femoral prosthesis' service life. Despite of these merits, due to femoral structure multiformity and complexity, people still lack effective means to get precise data for custom-made hip prosthesis design . To solve the problem, this theme has forwarded a new research method: firstly based on computer-aided CAD,CAE and digital image processing technique , the information contained in Computed Tomography scan data is utilized to rebuild femoral 3D-geometric shape and simulate femoral mechanical property, then the systemic experiment research for femora is conducted based on previous study. Research work comprises concretely below aspect: Breakthrough traditional means that CT slices are scanned by scanning device to digitize CT images ,CT images of femur will be unbrokenly transferred into PC through realizing communication of Spiral CT and PC based on the standard DICOM3.0 (Digital Imaging and Communication in Medicine),and CT images of femur will be displayed on PC. The new method will provide intact image data for rebuilt quality 3D model of femur, and the design thought and method realizing DICOM communication also will provide base for eventually realization of remote application for custom-made hip prosthesis design. Utilizing image process technique, CT images of femur will be processed to generate femur features contours through contours recognition and conversion of vectors in CT images of femur. Then in terms of B-spline skin theory, femur B-surface will be builted and closed topologically through femur features contours in Unigraphics as to rebuilt 3D femur and get geometric parameter exactly . During rebuilding of femur model, the theme has solved well some problems: orientation of contours, spline approximate, fractal of curved surface as to guarantee accuracy of model. Femur is collagen fiber reinforced composite material, composited with cortexand cancellous bone. Cortex and cancellous bone are anisotropic and inhomogeneity material. Due to the complex composite material, femur usually is simplified to homogeneity and isotropic material, so prosthesis designed are difficult to adapt to biomechanics environment in human body and reduce stress-shielding. In the study, by means of developed purposely program, the mechanics model of femur related to distribution of femoral apparent density and orientation of load will be rebuilted to simulate femoral anisotropy and inhomogeneity. Through computation by finite element method in I-DEAS and latter experiment research, biomechanics property simulated by this method near to experimental result. Mechanics experiment research of whole femur can not only get femoral straindistribution law and anisotropic biomechanics property, but also provide truthful experiment data comparison with previous computation result by finite element method to verify and improve model and finite element analysis work, even provide biomechanics parameter exactly for new style man-made joint design and clinical application. This study has obtained exactly geometric and biomechanics parameter of femur, so as to provide the base and good condition for custom-made hip prosthesis research and design through determination more exactly stress and strain of femur under physiologic load or after operated.