ABSTRACT
Objective To establish a three-dimensional finite element model and make mechanical analysis of "V"-type atlantoaxial reduction and internal fixation. Methods According to "V"-type atlantoaxial and internal fixation,based on screw-type Ⅱ design parameters,and using Pro/E 2001 and MSC.Patran 2005 software,we set up a finite element model and calculated the region containing the node scope of the force as the sites binding and 100N mechanics adding. Results The model looked realistic,geometric similarity.The deformation stress field mainly concentrated in the reset device V-tip arm bending and stability.The strength of its maximum stress was 4.78MPa,and the scope had 2794 nodes.V-type wing of the acute angle point of convergence of the premises to bear the stress intensity followed.It was 0.31MPa,and the scope had 1953 nodes.V-type wing by the end of edge was the smallest for the 1.22?10-3MPa,and there was the scope of 1730 nodes. Ⅱ-shaped fixed nail stress concentrated at the central parts of tooth and the art on both sides of teeth,with maximum stress intensity of 1.68?10-2MPa,and there was the scope of 1146 nodes. Conclusion The reduction and fixation devices to load at the time of recovery deformation forces and mechanical characteristics adapted to Ni-Ti shape memory alloy material functions and super-elasticity completely,which meets the clinical needs.
ABSTRACT
[Objective]To evaluate the biomechanical features of Ni-Ti shape memory alloy stemless femoral prosthesis.[Method]Using CT(computer tomography) scanning photographs of adult femur,three-dimensional model of the femur was built by CAD(computer aided design) software.Based on the the structure of femoral model,shape memory alloy stemless femoral prosthesis was designed.Three-dimensional finite element model was created for the normal femur,Ni-Ti shape memory alloy stemless femoral prosthesis,and traditional stemmed hip prosthesis.Under static loads and walking loads,the Von Mises stress distributions of each model were analyzed and compared.[Result]The stress distribution of shape memory alloy stemless femoral prosthesis was not obviously different from normal femur,stemless femoral prosthesis's proximal femoral stress was close to that of normal femoral model but significantly higher than traditional stemmed hip prosthesis.Von Mises stress of memory alloy claws was distributed evenly,and the Max was only 13.23Mpa,there was no stress concentration.[Conclusion](1) Ni-Ti shape memory alloy stemless femoral prosthesis has great biomechanical properties,may reduce the stress-shieding effect of the proximal femur.The fixed method that use memory alloy claws can make prosthesis fixed firmly to the bone and reduce stress concentration.