An olecranon fracture fixation system includes an intramedullary core that is dimensioned for insertion in an intramedullary canal of the bone, and a hollow shell that is dimensioned for insertion in the intramedullary canal. The shell includes fixation elements that extend outwardly away from a proximal end of the shell. A fastener is provided for attaching the shell to the core in the intramedullary canal. When the core and shell are inserted in the intramedullary canal, the fixation elements extend away from the fracture line of the bone, and when the core and shell are attached in the intramedullary canal, the fixation elements engage an end surface of the end section of the bone. In one example version of the invention, the system is an olecranon fracture fixation system wherein the fixation elements are dimensioned to engage the triceps tendon and an end surface of the olecranon when the core and shell are attached in the intramedullary canal of the proximal ulna.