Dual-trajectory pedicle screw system for improvement of fixation stability

摘要

A dual-trajectory pedicle screw system includes an internally threaded sleeve and including first part and cylindrical second part, the first part being recessed to form a space, and the second part including projections on top; a main screw including a universal head and a first conic member, the universal head including first and second threaded holes, the first threaded hole being inclined at a first angle, the second threaded hole being inclined at a different second angle, bottom of the universal head being a convex and rotatably disposed in the space; and an auxiliary screw including external threads threadedly secured to the first or second threaded hole so that the auxiliary screw is secured to the main screw at the first or second angle with respect to the main screw, a second conic member extending downward from the external threads, and a fitting member on top of the external threads.