| The precise aetiology of lunate ischemic osteonecrosis is not well known which cause dorsal wrist pain. It usually affects adults between 20 and 40 years of age, who are predominantly male manual workers.In 1910, Kienbfick, published his classic description of lunatomalacia, so it named Kienbfick's disease. Multiple factor are involved in lunate vessel destruction or increasing the pressure in lunate improvement then induce the loss of blood supply and lunate ischemic osteonecrosis.Lichtman classified Kienbfick disease into four stages. The selection of surgical procedures may accord to the stage of the disease. Stages I, there is an opportunity to adopt arthrodesis for a favourable biomechanical situation. Stages II, the major problem to solve is restore the normal blood circulation. In the earlier period, articular immobilization may be used. If there is no change for the better, surgical approach should be considered. For instance, vessel regeneration operation, include pure vascular bundle implantation and bone flap implantation combined with vessel fascia pedicel, muscular pedicel. In addition, vitodynamics mothed also can be used, radial shortening and ulnar lengthening, care must be taken to avoid ulnar impaction syndrome when vitodynamics performed. The last one is intercarpal arthrodesis, four-corner arthrodesis. Stages III, operation must performed as early because of the lunate collapse. There is still little evidence to support any particular form of operative treatment. Surgical removal of lunate usually adopted at initial stage, but presents a higher risk of articulatio carpi disorder. In recent years, a great deal of implant button have been employed. Autologous periosteum wrapped tendon with spongiosa homogenate, tendon bolus, capitate bone with Vascular pedicle, pisiform bone with vascular pedicle, artificial prosthetic appliance, the second head of metatarsal bone. These surrogate also could substitute for the lunate. Every method has its own forte and defect, there is no one standpoint recongized by all. Some of them presents severe side effect and should be verified more over. Stagesâ…£, proximal row carpectomy and partial or total intercarpal arthrodesis on the wrist are available. Wrist denervation also can be used, but it would speed up the arthritis.General from the second phase of lunate osteonecrosis the surgery can be carried out. If there is no lunate collapse symptom, total intercarpal arthrodesis would be carried out. Otherwise, partial intercarpal arthrodesis is operated after lunate collapse removal. The effect of the second one is open to question, so most operators utilize capitate bone substitute the lunate collapse.Anyway, there is no strong evidence to support any particular form of treatment. So the surgery option should be made according to the pathogenetic condition and the request of the function restore. The experience and technique also should be considered.The finite element method is created in the 1940's,and then widely used in various fields of engineering technology,used to simulate and solve a variety of engineering mechanics, electromagnetism, thermal and so on.Brekelmans firstly introducted the finite element method into the field of bio-mechanics,the method has been continuously developing during the following 30 years,getting great progress on the research of technology and mechanism,evaluation of medical devices,clinical simulation and other issues. With the development of the computer and software technology, at present, the three-dimensional non-linear model build with a finite element method can not only simulate real bones and joints, but also the surrounding ligaments, muscles and other soft tissue structure to join models, so have a more realistic simulation.Formerly, the finite element method is widely used in the orthopedics and oralogy, and there are many remarkable results in these fields. In the recent years, this method more and more be used of hand wrist biomechanical analysis.This research runs 3-demensional modeling using the finite element analysis software for the two kinds of treatment after the necrosis of lunar bone, which are fusion of carpal bone with and without reservation of lunar bone. The purpose is to analyze the maximum contact stress of radiocarpal joint after these two operations which are the fusion of the carpal bone and with removal lunar bone and evaluate the difference between the two methods according the comparison. Then get a model for analysis and treatment of wrist diseases.We receive the CT scanning data of functional position of wrist joint using Mimics software, and select the scope of wrist, radial and ulna we need, then establish the 3D modeling of the fusion of carpal bone and with removal of lunar bone. The modeling are imported into Geomagic 6.0 forming the STL file and thin the contacting articular surface by 1mm. Then the data is returned back to Mimics and the operation is done. The cartilage in the joint is formed by the 1mm dissecting crust. The two fusion models and the ulna and radial are install into contacting modeling in the Mimics. In Mimics, all the models are output by the form of INP file and then input into Abaqus software. In fact, these models which are comprised by triangle are divided into mesh by the Abaqus which has the function to transform the triangle to tetrahedron. All the materials are supposed to isotropism and line elasticity,The bone and cartilage are given the same material . Set up two models contact in the Abaqus,one is ulna-radial, and the other is scaphoid-radial. Then fix the inferior part of ulna and radial, bind the cartilage with wrist and ulna and radial. Exert the pressure of 10N,20N,50N,100N,150N,200N to the center of transverse cross section of the metacarpal bone along the perpendicular direction. After these procedures, we get directly the stress scattergram of radial scaphoid fossa and the maximum stress value according the FEA. Data indicate ,The stronger power was loaded, the bigger Differentials power values increased. Therefore, with the time lapse, loaded Differentials power will result in damage of articular surface and finally induce arthritis.Above all, we conclude that simple fusion of carpal bone with removal of ulna make the scaphoid fossa to accept greater stress. If the area accepts the greater stress than normal for a long time, it will be vulnerable so as to induce arthritic. So after the collapse of ulna, we could excise it and at the same time, stuff the absence of ulna using the capitate bone osteotomy and bone grafting. Then the new joint will be formed to share the greater stress in the lunate fossa. In this way, the rate of arthritic in the lunate fossa will be lessened. This provide a proof for those heavy manual workers who undergo arthrodesis of wrist will be easier to get arthritis than light manual workers.Thereout ,We explore a new model to analyze the wrist disease and its therapeutic efficacy.
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