| Resurfacing arthroplasty of hip is a popular procedure for younger active hip replacement patients. Initial fixation of the femoral component in hip resurfacing is key to the enduring survival of the prosthesis.To constructing of A Proximal femur after RSAH 3-D finite element model,and also To determine the effect of cement mantle varying in thickness on stress distribution and stress shielding in the proximal femur following hip resurfacing arthroplasty,in order to find the adaptive methods to fixing implant pin.Purpose To constructing of A Proximal femur after RSAH 3-D finite element model, and also provides an effective model for biomechanical analysis of Proximal femur. To determine the effect of cement mantle varying in thickness on stress distribution and stress shielding in the proximal femur following hip resurfacing arthroplasty(RSAH),in order to find the adaptive methods to fixing implant pin.Materials and Methods 1.A normal hip joint from an adult male volunteer subject was scanned by CT and the images of every transvestite section were obtained. A complete resurfacing implant were used. A Proximal femur after RSAH 3D reconstruction model was constructed with MATLAB and ANSYS software.2. Different bone material parameters were adopted according to the relation to physiological condition, and divide elements in ANSYS software, and the A Proximal femur after RSAH 3-D orthotropy finite element model was constructed.3. Simulation of normal standing was made on the model to set boundary condition and loading. Then calculate it. The model was validated in contrast to the date of literature.2.A normal hip joint from an adult male volunteer subject was scanned by CT and the images of every transverse section were obtained.A complete resurfacing implant were used. A Proximal femur after RSAH three-dimensional(3D) reconstruction model was constructed with MATLAB and ANSYS software.The implant angles of model were 140°.Different material parameters were adopted according to the relation to physiological condition, and divide elements in ANSYS software, and the a proximal femur after RSAH 3D orthotropy finite element model(FEM) was constructed.4 different thickness of cement mantle around implant pin 3D-FEM were constructed base on FEM after RSAH.Different thickness of cement mantle were 0mm,1mm,2mm,and 3mm.Put a pressure with a 238% body weight (BW) force load applied to cup and a 104% BW abductor force was applied on each model.Analyze the regular pattern of stress distribution and calculate the ratio of stress shielding in different regions on each model.Results A 3D orthotropy FE model of A Proximal femur after RSAH was established successfully, including 89 961 nods of 448 159 units.The maximal Von Mises stress occurs on femur neck. The stress analysis was the same as the results of literature and the actuality. The obvious change of stress was presented mostly in femoral neck in all the models.The stress in other regions showed slightly changing. Comparing with the 0mm cement mantl model,The stress of 1mm cement mantle model showed slightly decreasing.The stress of the 2mm and 3mm cement mantle model was obviously decreased comparing with 0mm and 1mm cement mantle model. Comparing with the 0mm cement mantle model,The ratio of stress shielding of the cancellous bone around the implant pin in lmm cement mantle model has no marked change,but increased obviously in the 2mm and 3mm cement mantle model.The cement around implant pin not thicker than 1mm produced slightly effect to the stress decreasing and did not result in marked stress shielding in the proximal femur following RSAH.Conclusion A 3D orthotropy FE model of A Proximal femur after RSAH can be constructed base on CT images, and provides a reasonable and effective model for biomechamical analysis of RSAH. The ratio of NASA is the key factor that prediction the collapse of femoral head necrosis.And about 25% of ratio of NAVA was the critical value of collapse of femoral head necrosis. |
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