Study On Elastic Fixation Of Phalangeal Fracture With 3D Printing

In the field of external fixation of phalanx fractures,in order to void the poor permeability of plaster,unstable of high polymer bandage,and splint compress marginal skin,so the purpose of this paper is to study a kind of personalized elastic external fixator with unequal stiffness,which can meet the biomechanics of human hand.The external fixator not only can match the shape of the patient’s fingers,but also can match the fracture site of the patient,which can achieve accurate and precise fixation of the fracture site of the phalanx.In this paper,the patient with distal thumb phalanx fracture as the research object,the main contents are as follows:1.Three-dimensional reconstruction of thumb model and design of external fixator model.The reconstructed thumb model consists of the three-dimensional models of the thumb bone and the entire thumb.Using the hand CT data of the patients with phalangeal fracture,the threshold segmentation method of Mimics software was studied,and the three-dimensional models of hand skeleton and hand were reconstructed.In order to simplify the calculation,the three-dimensional models of the thumb bone and the whole thumb were segmented.According to the three-dimensional model of the whole hand,the personalized,and breathable external fixator with unequal stiffness was designed via 3DMax.2.The establishment of finite element analysis(FEA)model.Three kinds of solid models were established to be used in FEA which include thumb bone,thumb soft tissue and external fixator.The thumb soft tissue model can be obtained by performing a Boolean subtraction in the finite element software,and the materialized thumb bone model and the entire thumb model are used as objects of Boolean subtraction.In modeling,the NURBS surfaces of each model were manually planned,and the meshes were partitioned by the hexahedron dominant partition method.3.Finite element analysis.To explore the stress and deformation of the fracture site when the surface of the external fixator be hit by different external force.The external force of 49 N applied on the surface of the external fixator,and the surface area is 1cm2.though the maximum stress focus on the fracture site which value is 2.0435 Mpa,the fracture site of the small deformation can be ignored.4.Research on materials and 3D printing technology for the external fixator.By comparing formed external fixators which were printed respectively by TPU,PLA,photosensitive resin.The selection of TPU was proved correctness.Then compare external fixators which formed respectively by granular and linear TPU,as well as the use of the printer equipment,to determine the linear TPU is better.Ultimately,the linear TPU and the 3D printer of Ultimaker2+ were selected to form external fixator,and this external fixator is best suited for phalangeal fractures.The external fixator in this study has gone through the entire process from scratch,and finally,the rapid prototyped external fixator has realized the breathable,reliable fixation,wear comfortable.In addition,the external fixator has an exact biomechanical performance indicators,which is the surface of brace with the area of 1cm2 can withstand impact of 49 N external force without re-injury to the fracture site.