Vertebral fixation device for the treatment of spondylolisthesis

Vertebral fixing device for treating spondylolisthesis which has a screw that has a spherical head designed for fixing to a bone, a tulip that incorporates vertical notches aligned with each other in which a bar is placed, forming a link between screws of other devices and an interior threaded section into which fits a closing screw that rests on the bar and moves a locking cap, essentially wherein the tulip has a cavity inside and below, delimited by an upper spherical wall and a lower conical wall in which a rosette is located, formed by an upper protuberance that has a conical section ending at a top with another cylindrical section that serves to guide the movement axially inside the tulip and which on its upper face has a series of flexible slats arranged down from the upper protuberance, separated by slots that form a housing in which the head of the screw is housed and which has free polyaxial orientation movement, there being a threaded section located next to the cavity in which a tightening screw moves, acting on the upper face of the upper protuberance of the rosette to close the slats by pressure on them against the conical wall, slats which in turn will press against the head of the screw to fix it in position.