Evaluation of fixed power to the low profile of the spinal implant

Abstract

Spinal implants used for treatment of spinal diseases are required to have high strength and rigidity, and high mating force to fix rods. On the other hand, there is no report on the mechanisms of these fittings and discussions on the breakage of implants. Also, in recent years, the problem of deterioration in quality of life (QOL) such as compression of the skin of the treated patient due to the use of a large implant made abroad has also been reported. While miniaturization of the implant device is required, on the other hand, reduction in strength due to miniaturization is concerned, and the mechanism of low profile is still unknown. Therefore, in this study, we examined the low profile of the spinal implant device. As a result of the experiment, it was found that the reduction of the height and the securing of the number of threads as well as the suppression of the opening by increasing the stiffness of the screw socket are effective for low profile. From observation results, it was found that the cause of decrease in fitting force is wear and plastic deformation of thread surface as well as reduction of contact area due to incomplete contact between threads.