The present disclosure relates, in some embodiments, to spinal fixation systems that may comprise a bone screw, a body, and a pressure cap. A bone screw may comprise a head at a proximal end, a bone connection element at a distal end, and an external protrusion on a head of a bone screw. A body may comprise a proximal end, a distal end, a mounting rod receiving channel at a proximal end, and a bone screw head receiving channel 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 an internal recess on a distal end. An internal recess may be configured to mate with an external protrusion of a bone screw so as to limit the movement of a bone screw.
