Abstract: A cannulated screw and core assembly includes a cannulated screw having an elongate shaft with a central bore including internal threads and a recess at a proximal end for receiving a tool for applying torque to the screw; and a complementary core shaped to be threaded into the central bore and having a frangible portion. Rotation of the core causes the core to separate at the frangible portion, resulting in a screw having a reinforcing core extending substantially along the internal bore of the screw. The disclosure includes a tool for attaching the disclosed cannulated locking screw to a bone fragment or plate. The tool may include a barrel shaped to receive the core assembly and includes a handle attached to a proximal portion of the barrel and a shank that extends through the barrel to engage an end of the core.