A spinal fixation assembly includes a pedicle rod and pedicle screws which secure the pedicle rod to the spine. Each pedicle screw includes a head configured to receive a portion of the pedicle rod, and a threaded portion extending from a first end of the head and configured to engage a vertebra. The pedicle rod is secured to the head by a fastener. The head includes a breakaway region that defines a location in which at least a first portion of the head can be easily separated from the remainder of the head upon application of sufficient force to the first portion. A minimally invasive method of implanting the spinal fixation assembly is disclosed.