| Summary: | 碩士 === 國立臺灣科技大學 === 機械工程系 === 96 === Spinal instrumentation has been widely used to treat the spinal trauma, disease and degradation. In clinical observation, the spinal fixator failed in the interface between the plate and screws because of the stress concentration. Therefore, designing the spinal implants with a sufficient strength was an important issue.The purpose of this study was to compare the different angle effect to the plate fixator.
Three-dimensional finite element models for pullout and bending strength were developed by using COSMOSWorks. Seven types of the plate angle (0˚, 5˚, 10˚, 15˚, 20˚, 25˚ and 30˚) and one commercial type with a plate angle of 22˚ were discussed and analyzed. In the pullout analysis, increasing the plate angle could increase the pullout strength of new anterior thoracolumbar plate. Two kinds of bone screws were analyzed and discussed including the traditional bone screws and the unthreaded bone screws. The pullout strength of the traditional bone screws was greater than that of the unthreaded bone screws. Nevertheless, the tendency of these two kinds of screws was almost the same. In the bending analysis, the von Mises stress of the screw holes and the screws were changed by different plate angles. Increasing the plate angle would decrease the maximal von Mises stress of the implants. Therefore, the larger plate angle could provide the smaller von Mises stress and reduce the stress concentration.
We concluded that increasing the plate angle would increase the pullout strength and bending strength of anterior thoracolumbar plate fixator. The results of this research may provide the useful information to engineers and surgeons.
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