A clamp assembly for repairing a bone defect according to the invention includes a base, a cap opposing the base, and a post connecting the cap and the base in a fastening position on adjacent bone plate and surrounding cranium. The clamp assembly may further include an applier interacting with the post to position the cap and base in the fastening position. A method according to the invention includes placing the base and cap on opposing internal and external surfaces of the bone plate, with a portion of each of the base and cap overlapping a border of junction between the bone plate and surrounding bone. The post is rotated to bring the base and cap to the fastening position. The method may further include removing a distal portion of the post projecting from the cap and leaving a proximal portion of the post projecting from the cap and which can be deformed to secure the base and cap in the fastening position.