Three-dimensional Finite Element Model And Operation Simulation For Cleft Lip

Face plays an important role in people's aesthetic feeling. As the means of rectify facial abnormality, the operations of Craniofacial Surgery are paid more and more attention on by people. Generally speaking, sanction is applied to make the face normal in the operation. Therefore, stress analysis has a great meaning for a good effect on the Craniofacial operations.The cleft lip is congenitally facial deformities with high occurrence rate in China. For the treatment of cleft lip, surgical procedure involving Millard or Tennison methods is usually employed. Though the surgical procedure has been improved greatly during the past half century, it's still quite difficult for the surgeons to anticipate the postoperative outcome accurately due to the structure complexity and deformation of soft tissue. There are still high occurrence of facial abnormality or dehisce after the operation, leading to multiple operations for the treatment of the same patient. The aim of this study is to build a three-dimensional (3D) finite element model (FEM) of the cleft lip, simulate the interaction between the soft tissue and maxillary, especially the stress distribution of soft tissue/skin during surgical operation, and provide more accurate prediction of possible treatment for surgeons.The setup of 3D FEM consists of two major steps. The first one is the reconstruction of 3D geometrical model of the cleft lip from scanning data acquired by computed tomography (CT). The second step is the build-up of finite element model for cleft lip. With the 3D geometric model from CT data, we got the 3-D geometry model by the methods of segmentation,geometrical mimesis and 3-D reconstruction. We divided the model with surface gridding and then we got the volume. We divided the volume model into volume gridding of elementary tetrahedrons. Then material property of all the tetrahedrons was calculated respectively from the linear elasticity model and CT density. We input the model into The Finite Element Software ANSYS9.0. After the definition of boundary conditions and forces simulating the surgical procedure, we got the simulation result using the Finite Element analysis program. The result contain three parts: the value of pull based on different materials, the deformational situation of the entire model, the stress situation of the entire model.