The present invention relates to a bone fixation assembly for securing a fixation device, such as a bone plate, to bone. The assembly includes the fixation device, a bushing, a fastening screw, and a locking screw. The bushing is seated within a through hole in the fixation device and can rotate within the through hole and has a sidewall with a bore. The sidewall has at least one slot for allowing outward expansion of the sidewall against the through hole to thereby lock the bushing at a selected angle relative to the axis of the through hole. The fastening screw has a threaded shaft for insertion through the bore of the bushing and threads into bone to secure the bushing and fixation device to bone. The head of the fastening screw fits in the bushing and includes a radial wall and open end defining a recess. The radial side wall has at least one slit for allowing outward expansion of the radial wall thereby outwardly expanding the sidewall of the bushing. The locking screw has a body that threads in the head of the fastening screw to thereby outwardly expand the radial wall of the fastening screw.