The Study Of Mini-external Fixation And Kirschner Wire For The Treatment Of Bennett Fracture By Three-dimensional Finite Element Analysis

Objective:To analysis of mini-external fixation and percutaneous k-wire internal fixation for Bennett fracture by FEA, and to compare the two fixations for treatment of that fracture by oberserving the nephograms of displacement and stress of the distal and the proximate pieces of fracture.Methods:(1) The stage of establishing a3-D digital model:In order to obtain the Dicom digits and restore into computer, the right hand and distal of the radial of a healthy25years old volunteer man, was scanned by CT with0.625mm intersection. Introducting all the digits to Mimics, the first and second metacarpal bone and the trapezium were formed into three-dimensional model, and mini-external fixation and k-wire, which were output*.STL style.(2)Modeling solid model:Inputting the former digits into Geomagic, we can obtain the solid volumn of them and output the digits into*. IGES forms.(3) Modeling finite element models and analysis:In the Ansys,the models, which were Bennett fracture and the mini-external fixation or k-wire internal fixation for it, were established and fixed and attributed to different types and properties, and then the finite element models were setted up. After that, the same load(100N) was exerted on both mini-external fixation and k-wire internal fixation for the fracture of the Bennett respectively. At the end, the none-line solution was analyzed. the nephograms of displacement and stress of the distal and the proximate pieces of fracture were gotten.Result:The high-precision three dimensional finite element model of mini-external fixation and percutaneous k-wire internal fixation for the fracture of the Bennett were established. The nephograms and digits of displacement and stress of the distal and the proximate pieces of fracture were obtained under x-axial100N load. In mini-external fixation model, The max and the min of displacement of the proximate piece of fracture is(X-component of displacement)-0.342mm and-0.174mm,the average is-0.258mm.Abut that of distal one is-0.492mm and-0.293mm,the average is-0.393mm. Relative displacement of the distal and the proximate pieces of fracture is0.135mm.Using the same method, can we got the same digits of the displacement vector sum of them. Relative displacement of the distal and the proximate pieces of fracture is0.026mm. The stress nephogram of the pieces of fracture is-81.234MPa-134.035MPa; In k-wire internal fixation model, The max and the min of displacement of the proximate piece of fracture is(X-component of displacement)-2.546mm and0.504mm,the average is-1.021mm.Abut that of distal one is2.573mm and2.476mm,the average is2.524mm. Relative displacement of the distal and the proximate pieces of fracture is3.545mm.Using the same method, can we got the same digits of the displacement vector sum of them. Relative displacement of the distal and the proximate pieces of fracture is2.643mm. The stress nephogram of the pieces of fracture is-760.386Mpa-184.349MPa.Conclusion:(1) I have grasped the method to establish finite element model and setted up the high-precision three dimensional finite element model of mini-external fixation and percutaneous k-wire internal fixation for the fracture of Bennett by learning softwares of Mimics10.01、Geomagic Studio10.0、Ansys12.0.(2) The fixation stability of mini-external fixation for the fracture of the bennett is better than that of percutaneous k-wire internal fixation. With steping down incidence rate of the traumatic arthritic of it, having the value effect to function of the hand and speeding the heal of fracture,the former is a more perfect treatment than that of the later.