Disclosed herein are spinal fixation systems that may comprise a screw, a body, and a pressure cap. A screw may comprise a head at a proximal end, a bone connection element at a distal end, and a first mating element disposed on a head of a pedicle screw. A body may comprise a proximal end, a distal end, a mounting rod receiving channel at a proximal end, and a screw head receiving aperture at a distal end. A portion of the mounting rod receiving channel may be operable to receive a compression element. A pressure cap may comprise a proximal end, distal end, and a second mating element on a distal end. A first mating element of the screw may be configured to mate with the second mating element of the pressure cap thereby limiting the pivotal movement of the screw to that of a monoaxial screw.
