A pedicle screw assembly includes a fixation element, a coupling element, a bottom saddle, and a compression nut. The fixation element is adapted to engage a bone having a head portion and a shank portion. The coupling element includes an internal bore sized to receive the shank portion, a seat adapted to support the head portion, and a retention region in a sidewall of the coupling element that extends from a proximal ridge to the seat, the retention region including non-parallel opposed internal surfaces therebetween. The bottom saddle is disposed within the retention region and including a frustoconical outer surface formed by opposed walls and a rod-receiving region to receive a rod. The compression nut is coupled with the coupling element and adapted to translate a force to the head portion through the rod and bottom saddle to prevent relative movement between the fixation element and the coupling element.
