A bone fixation system includes a plate and a set of fixation locking screws. The plate defines a set of locking screw holes each having an internal thread. Each respective locking screw has a head with an external structure that is adapted to self-tap into the internal thread of a given locking screw hole to secure the respective first-type fixation locking screw at an surgeon-directed angle relative to the plate. This angle is defined during forcible insertion and rotation of the respective locking screw into the given screw hole. The system may also include unidirectional locking screws. In a preferred embodiment the plate and first-type of screw are made of different metals, with the plate made of titanium alloy and the screw made of cobalt chrome alloy.