There is provided a modular pedicle screw assembly that includes various components which may be configured in various manners so as to provide different functionalities to the pedicle screw assembly. This advantageously decreases surgery time, reduces repetitive and tedious surgical steps, and allows for streamlining inventory of expensive medical equipment. In one embodiment, a pedicle screw assembly includes a pedicle screw, a rod holding element, an insert, a rod, and a set screw. The pedicle screw includes a threaded shaft and a cap. The rod holding element includes a screw hole, an insert bearing area, a chamber, chamber walls, a saddle area, and a threading area. The insert is disposed within the chamber, and the insert defines a bearing surface, an upper surface, side walls and a receiving area. The insert is positioned within the chamber such that the insert bearing surface contacts the rod holding element insert bearing area; additionally the side walls of the insert can bear against the chamber walls. The pedicle screw is positioned so that the screw shaft passes through the screw hold of the rod holding element and the screw cap rests within the receiving area of the insert. The rod is disposed so as to rest on the upper surface of the insert; and the set screw, joined to the threading area of the rod holding element, secures the rod to the upper surface of the insert. The insert may have a uniplanar configuration which allows movement of the insert, prior to final attachment, in a plane of motion. The insert may optionally have a monoaxial configuration which prevents movement of the insert.