Systems and methods for intermedullary bone fracture fixation are described herein. The fixation device includes a main body having a flexible state and a rigid state. The fixation device further includes a proximal interface coupled to a proximal end of the main body to anchor the fixation device to an exterior surface of the bone and a distal interface coupled to a distal end of the main body to anchor the fixation device to an interior cavity of the bone. The fixation device further includes a locking interface to configured to convert the main body from the flexible state to the rigid state.