An intramedullary bone fixation device is provided with an elongate body having a longitudinal axis and an actuator to deploy at least one gripper to engage an inner surface of the intramedullary space to anchor the fixation device to the bone. Methods of repairing a fracture of a bone are also disclosed. One such method comprises inserting a fixation device into an intramedullary space of the bone to place at least a portion of the fixation device on one side of the fracture, providing rigidity across the fracture, and operating an actuator to deploy at least one gripper to engage an inner surface of the intramedullary space to anchor the fixation device to the bone. Various configurations allow a segmented device body to lock in the intramedullary space before and/or after fixation of the bone.