| Background:With the rapid development of building industry and communication, Bursting fracture of distal femoral fracture took place usually,for example traffic accidents,high-altitude fallings,crashing wounds.and the state of an illness were serious and the mutilation rate was higher than others.These patients usually combine craniocerebral trauma,other limbs and internal organ injury.So, the clinical procedures was difficult, and curative effect was poor,and even lead to decurtation of limbs and the dysfunction of knee.Traditional treatment viewpoint of distal femoral fracture were traction and close restitution et al,but nonoperation treatment were unfirm, there were not reposition of anatomy and fuction, and lead to malunion and disunion,influented the functional rehabilitation.Recently, these methods were be replaced by discissiofixation.Ordinary plate was been first choosen for treatment of distal femoral fracture,and it function of healing was better than nonoperation,Because poor intension of fixation,wider dissection of periosteum,beforehand bending and defection of biomechanics,the ordinary plate was replaced by the second generation fixation for example angle steel and condyle fixation. The angle steel fixation,there were facility lead to intraoestrophy malformation of knee,and the condyle fixation were wider area of trauma than others,and its effection of treatments were not well.The fixation of LISS was be researched by many orthopedist based on the second generation fixation.This system was suitbable to laterofemur,created length wise extrusion and aniso thickness of stick,stress divergence,it was be choosen by orthopedistBut the LISS steel of domestic were import production,also the fixation made in china that were be replicate, the import production were be designed according to anatomy of white people,if we would apply to Chinese,whether suitable or not were not be to final conclusion.There were short of clinical anatomical parameter;Because lower limbs were bigger weight loading,the classification of fracture were complex and be drug by amphomuscle,There were usually to take place of breaking of screw or steel,also many researcher were study biomechanical analysis, there all were experiment in vitro and theaccuratissime were poor.So we used clinical trauma orthopaedics, human anatomy, modern imageology,3-D reconstruction of computer technique to research of distal femoral LISS fixation on new screw position,how to orientate,and decrease complicatiom.With finite element analysis simulation technique,we supplied digital physical model to improve fixation,and also established a way on how to study with3-D digital,precise position and quantitative.Objective(1) To reconstructed distal femoral models(2) To provide a basis on fracture of distal femoral,22anatomical parameters of distal femoral fixation were be measured by digital3-D.(3) To3-D digital simulate of fracture of distal femoral LISS steel fixation and proof parameter feasibility,and apply operational reference plan.(4) we would analyze three types of fixation and two types of motion FEA models evaluated the stress of screw,stick stress and to compare with different types and motions.To supply the suggestion of fixation improvement and verificate the feasibility fixation application.(5)We retrospective analyzed15cases fracture of distal femoral modus operandi therapeutic efficacy and prostecdtive efficacy and compared with FEA results,verificated reliability of FEA results and applied suggestion of operation.Methods and materials:(1) To collect CT primary data and establish database of3-D reconstruction models:CT scanning images of health adult physical examination were collected.Scanning condition is that voltage is120kv,electric current is150mA, level thickness is1.25mm and512×512matrix.The data included30cases healthy adults (From the lower of greater torchanter of femur to upper of tibia1/3,18～41years old, average32years old)(2) The measurement of parameter on distal femoral fixation of LISS:With Mimics registry three plane(transverse plane,coronal plane,sagittal plane),active "Tool" toolbar,choose "Distance measure tool"to measure follow parameter on2-D imaging:The width of condylus medials femoris; The width of condylus lateralis femoris;The angles of condyles of femur and trunk; The length of cancellated bone on distal femur;We divided5segment from the lower of greater trochanter of femur to lateral epicondyle,and measured cortical thickness and transverse diameter of pulp cavity,and compared the difference of two sides.(3)We imported3-D models of LISS into15cases of3-D models of distal femur,and registrated and simulated of situation of screws and steels,read the coincidence. (4)A young man’s distal femur was scanned by CT with lmm interval. Then, the jpg-format data of CT was input into computer. Used Mimicsl3.0"Threshold" to choose distal femur reconstuction segment,We constructed3species and5ligaments digital models. We import3-D models of LISS into3-D model of distal femur,and registrated,exported by "Stl" files. With Ansys productsll.0,We construced finite element model,fixed distal femurs,oaded340N on greater trochanter of femur,Analysised stress on middle/tail of screw and upper/middle/lower segment of steel.(5)We retrospective analyzed15cases fracture of distal femoral modus operandi, therapeutic efficacy and prostecdtive efficacy and compared with FEA results,verificated reliability of FEA results and applied suggestion of operation.Results:(1)The width of distal femur were (84.80±1.27) mm and (84.60±1.40) mm;The A-P of condylus lateralis femoris were (67.36±1.41) mm and (66.27±1.42) mm; The basic of condylus lateralis femoris were (42.53±3.42) mm and (42.98±1.25) mm; The angles of condylus lateralis femoris and trunk were (7.58±0.69) mm and (7.66±0.79) mm; the width of interior and laterioros integumentale were to increase,but the scope of change was small, the interior scope of change was [left (4.37±0.55～3.61±0.43) mm]。The width of medullary cavity were to increase, the scope of change was biger [left (15.61±0.83～21.77±1.31) mm]; There were no difference between two sides.(2) The canal of screws were increase from uper to lower of femur. There were no difference between two sides.beside for B,C,E and C,B; Among D、E、F, E was difference.On the left,completely suit case was10,5cases were not suitable; On the right completely suit case was8,7cases were not suitable.(3)We reconstructed3-D models of distal femur on LISS fixation system,43, 536units,41,256nodes,The shape of3-D models was similar with entity;(S1～S5),The stress of steel was to be increase,and the Spearman of stress and segment was0.966, P<0.001; A1～A5, The stress of steel was to be increase, and the Spearman of stress and segmentwas0.895, P<0.001, but A6was small; According to the cloud atlas of stress we could see that these were well distributed except A1,Form distal to extremity of screw,The stress of screws were to increase, the Spearman of stress and segment was0.913, P<0.001。The stress of countersinks were difference from steels,the stress of steel were bigger than countersinks.(4)We reconstructed3-D models of distal femur on LISS fixation system,41,245units,39,140nodes,The shape of3-D models was similar with entity;(S1～S5),The stress of steel were to be increase,and the Spearman.of stress and segment was0.988, P<0.001; Al～G, The stress of steel was to be increase, and the Spearman of stress and segmentwas0.834, P<0.001, B and G were bigger; According to the cloud atlas of stress we could see that these were well distributed except A1,Form distal to extremity of screw,The stress of screws were to increase, the Spearman of stress and segment was0.499, P<0.001。Among S1～S5, A1～A5,The stress of countersinks were difference from steels,the stress of steel were bigger than countersinks. B and G were bigger than S5,there were significance between each other.(5) We reconstructed3-D models of distal femur on LISS fixation system,42,011units,40,010nodes,The shape of3-D models was similar with entity;(S1～S5),The stress of steel was to be increase,and the Spearman of stress and segment was0.958, P<0.001; The stress of screws were to be increase, and the Spearman of stress and segmentwas0.903, P<0.001; According to the cloud atlas of stress we could see that these were well distributed except Al,Form distal to extremity of screw,The stress of screws were to increase, the Spearman of stress and segment was 0.943, P<0.001. Among S1～S5, A1～A5,The stress of countersinks were difference from steels,the stress of steel were bigger than countersinks.,there were significance between each other.(6) We reconstructed3-D models of distal femur on LISS fixation system From A to D, Stress of each segments were decrease. According to the cloud atlas of stress we could see that,the segment of A was concentrate,but the stress of all segments were smaller than894～1034MPa.Conclusion:(1) The diameters of distal femur were smaller than white people. According to the The width of distal femur, The A-P of condylus lateralis femoris and the basic of condylus lateralis femoris:The cancellated bone screws were not longer than85mm on laterior distal femur.From posterior to anterior, screws were not longer than70mm o The screw of posterior steel were not longer than45mm, and to prevent screw crossing condylointergroove,There were no difference between two sides.According to the angles of condylus lateralis femoris and trunk, the trunf of LISS was to be8°introversion angle,and made to suit to distal femur,and prevent angulation malformation.From Slto S5,the width of os integumental change from thinness to thicken and then from thicken to thinness,the width of cavitary was opposite.when twisted,we could referto our parameter and prevent to penetrate cortex and decrease compliation of operation.(2)The srew canal of diatal femur,we could choose25mm～30mm screw on NO.5,4hole,30-35mm screw on NO.3hole,40～45mm screw on NO.2hole,45mm～50mm screw on NO.1hole. There were no difference between two sides.A,B,C,D holes,the screws were difference between each others,except C-B, A and G were bigger than C and B,50mm～55mm screw on B hole,60mm～65mm screw on A hole;65mm～70mm screw on G hole;There were difference between two sides,D,E,F holes, except E-F, E and D were bigger than F,75mm～80mm screw on E,D hole,There were difference between specification and distal femur of Chines.(3) We reconstructed3-D models of distal femur on LISS fixation system,and the stress of all segments were smaller than894～1034MPa, The fixation system were not collapse;Whole putting screws group and nut blocking group were to be fatigue break.The stresses of part putting screws group were concentration, were to be fatigue break to compare with nut blocking group. |
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