| objective:Child subtrochanteric fracture is a low incidence of severe fracture. It includes non-operative therapy and surgical therapy. The anatomy-type plate of children proximal femoral was specially designed by our department for children in 2007.Through the biomechanics and preliminary clinical application,the following questions were founded : Fracture displacement appeared after anatomic reduction and fracture displaced again after operation. The fracture displacement is slight and can be accepted .But for further perfect my classmate will improve the children proximal femoral anatomy-type plate into children proximal femoral anatomy-type locking compression plate.To the children locking compression plates(LCP) for femur anatomy,there are some differents of the femoral anatomical configuration in children and the fixation direction in the LCP is certain .But not all of the proximal femoral screws implanted femoral neck in all cases in clinic,and the design of 8 fonts combi_ holes doesn't fit the space between the bolt holes in the upper anatomical plate of all children . This subject is committed to the improvement of plate into two locking holes and one common hole in the anatomical part and locking holes in the straight part . Inevitably there are three types of combinations. Firstly, we should build the three dimension finite element model of child subtrochanteric fractures and secondly simulate the fixation of the children femoral screws plate.Then we tested and analyzed the screws and the plates by the method of three dimension finite element analysis .So we could optimize the screws and plate systems.Methods : To scan the both sides of the proximal femur by SCT in order to get DICOM-formed computer image data.To establish the children proximal femur fracture finite element model with Mimics 12.11 digital 3-D medical image interactive software and ABAQUS 6.9 finite element processing software .Import the datas of composite screw to the FEM,set the boundary and load condition,analyze the stress and strain value of screw and fracture interface.Results: We established 3-d finite element models of the child subtrochanteric fractures and the anatomy of the femoral locking plate, ordinary screws, and locking screws. We aquired the stress distribution and the maximum stress value of the steels and screws, and the stress concentration areas. Through three kinds of loading we aquired the stress distribution and the datas:â‘ For ordinary screws ,the stress was concentrated between the screw and the compact bone in combination 1,and from the middle to the far end in the screws in combination 2 and 3.â‘¡For locking screws the stress was concentrated in the interface of the screws and the plate in any kind of combination.â‘¢The stress was distributed more evenly in the screws in the middle of the plate and the highest stress in the distal screws.For the plate the stress was focus on the interface of the anatomy-type part in the proximal and straight part in the far side.â‘£There were some differences in the three kinds of combinations of comprehensive stress under different loadings.Conclusion: 1.The three-dimensional finite element modles of children subtrochanteric fractures and the locking plates, ordinary screws and locking screws of proximal femoral for children we aquired are vivid and objective. It will have some guidances to design and improve the entity screws and plates2. Comprehensive stress under different loadings were different in three improved plate and screw system .Every kinds of combination has its own advantages.and they can all reach the effect of the fixed firmly.3.Considered the differences of the femoral anatomical children were discrepancy,and not all of the proximal femoral screws were implanted in femoral neck in all cases.We could choose the improved anatomy-type locking compression plate of children proximal femoral.The anatomy-type locking compression plate of children proximal femoral would be feasible by finite element mechanical test. |
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