The Morphological Parameter Analysis And Biomimetic Reconstruction Of Trabecular Bone

Damaged trabecular bones are difficult to self-recover,resulting in structural dysfunction and affecting normal activities.External implants are needed to help recover living standard.The existing solid implants have the disadvantages of easily causing body discomfort and high fixation failure rate.In order to reduce the impact of solid implants,the structural design is developing towards the porous direction.Trabecular bone is a porous structure that affects the biomechanical properties.Therefore,the design of porous implants that simulates trabecular bone has become an important focus.The porous structure reconstructed with trabecular bone images is porous but difficult to process.The use of a porous structure such as a cube can ensure the supporting effect,but the structural difference is large.Therefore,designing a uniform porous structure model is of great significance for designing implants.In this paper,the trabecular bone in the femoral head is taken as the research object,and the calculation methods of morphological parameters and mechanical properties are studied and calculated.A design method of porous structures imitated structure and function of trabecular bone by topology optimization method is proposed.The main contents are as follows:Firstly,according to the non-uniform characteristics of trabecular bones,the trabecular bone morphological parameters calculation method was studied and the thickness,number,separation,structure model index,connectivity and other parameters were measured and analyzed.It was found that the morphological parameters of trabecular bone showed a certain variation from the edge to the middle.The morphological parameters were used to quantify the structural characteristics of trabecular bone,and it was used as the objective function and test standard for the reconstruction of porous models,which improved the rationality of structural design.Then,aiming at the complex structure connection problem,the finite element method combined with the representative voxel method were used to calculated mechanical properties,elastic modulus,Poisson's ratio and shear modulus.And the change trend of the mechanical properties of the trabecular bone were analyzed,which provides a mechanical performance objective function for the reconstruction of porous models.The measurement results show that the mechanical properties of x,y,z directions are different,and the y direction(direction of pressure)is larger than other directions.The closer to the top edge of the femoral head,the denser distribution of trabecular bone,the larger equivalent value of the mechanical properties.Finally,aiming at the inconsistency of structure and function in the porous structure design method,a topological optimization method combining the homogenization method with the variable density method is proposed.The porous model is designed based on the volume fraction,structural direction and mechanical properties of trabecular bone.Then,the mechanical properties and morphological parameters of the model were measured to calculate the comparative structural differences.The results show that the error of equivalent parameters of the mechanical properties of the reconstructed porous model is less than 10%,which is 4% lower than the method based on the optimization of mechanical properties.The thickness,number,and separation do not exceed 6%,and the connectivity value is in the same range with trabecular bone,the anisotropy value is about 9%.t-Test of morphological parameters and mechanical properties showed no statistical differences between reconstructed porous structures and trabecular bone.It is proved that the designed porous models in this paper satisfy design requirements,which can be designed and implemented repeatedly.This method can greatly reduce the amount of computational data and facilitate the subsequent processing.The topological optimization methods are used to design the porous models based on the morphological and mechanical properties of trabecular bone.While this method ensures support and connectivity,the rationality of result design is improved,and the complexity and computational complexity of structures is also reduced.It provides an important basis for the design of reconstructed porous implants.