Analysis of stress induced by screws in the vertebral fixation system
نویسندگان
چکیده
OBJECTIVE To compare, using photoelasticity, internal stress produced by USS II type screw with 5.2 and 6.2 mm external diameters, when submitted to three different pullout strengths. METHODS Two photoelastic models were especially made. The simulation was performed using loads of 1.8, 2.4 e 3.3 kgf.The fringe orders were evaluated around the screws. In all the models analyzed the shear stress were calculated. RESULTS Independently of the applied load, the smaller screw showed higher values of shear stress. CONCLUSION According to the analysis performed, we observed that the place of highest stress was in the first thread of the lead, close to the head of the screws. Experimental study.
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