Establishment And Application Of Three-dimensional Finite Element Model Of Cranial-maxillary Complex And Rigid Internal Fixation For Craniofacial Fractures

Object: The purpose of this study was to establish three-dimensionalfinite element model (3-D FEM) of cranial-maxillary complex and rigid internalfixation (RIF) for craniofacial fractures with better similarity, and research onstress distribution during working occlusion and RIF of craniofacial fractures.Then the stress distribution was evaluated so as to provided theoreticallydirection for the diagnosis, protection of craniofacial fractures and RIF design.Methods: A young male skull with normal occlusion was adopted forCT scanned transverse section. Then the standard of DICOM was used totransfer the CT dates to personal computer. The super scientific calculatesoftware (Matlab) and the finite element software (ANSYS) were used to takeand analyse the date to establish the 3-D FEM of cranial-maxillary complex andRIF for craniofacial fractures. The working occlusion of cranial-maxillarycomplex were modeled; The stress distribution of zygomatic bone by attackingwas analysed to find the cause of zygomatic bone fracture; The stressdistribution and the mobility of fracture segment in craniofacial fractures withminiplates and microplates fixation under working occlusion, so as to evaluatedthe effect of the fixation method.Result: 1. A 3-D FEM of cranial-maxillary complex including cirticalbone, cancellous bone and dentition was established, which consisted of 170,840nodes and 673,618 elements. Then, a 3-D FEM of RIF for craniofacial fracturesincluding zygomatic bone fractures, maxilla fractures and orbital fractures werealso established, which consisted of 255,970 nodes and 1,022,820 elements.2. When cranial-maxillary complex was under working occlusion, the Von-mises stress of the caninus brace was 7.997 MPa, the zygomaticoalveolarcrest brace was 22.185 MPa, the zygomatic arch was 14.830 MPa, the pterygoidprocess was 32.959 MPa. There were higher Von-mises stress at the plates forRIF of craniofacial fractures, the highest Von-mises stress in the miniplates was101.478 MPa, in the microplates was 85.316 MPa, the most displacement offracture segment was 0.003245mm;3. When the zygomatic bone was attacked by force, the Von-mises stress ofthe zygomatitemporal suture was 26.760 MPa, the zygomaticsphenoid suturewas 43.476 MPa, the zygomatic-maxillary suture was 11.490 MPa.Conclusion: 1. The above mentioned methods were proved to befeasible in the establishment of 3-D FEM of cranial-maxillary complex and RIFfor craniofacial fractures and could improve the biomechanical similarity ofFEM effectively. The 3-D FEM could analyse the regularity of stressdistribution of craniofacial fracture by using RIF.2. There were higher Von-mises stress at canius brace, zygomaticoalveolarcrest brace, zygomatic arch, pterygoid process in the working occlusion.3. The RIF with miniplate and microplate were safe and effective.4. There were higher Von-mises stress at zygomatitemporal suture,zygomaticsphenoid suture and zygomatic-maxillary suture When zygomaticbone was attacked by force.The above position of zygomatic were feasible tofracture and displacement.