Bone screw with two-part screw head

A bone fixation device comprising:

• at least one bone fastener comprising:
• a shank having a longitudinal axis extending from a bottom end to a top end;
• a head positioned adjacent the top end of the shank and having at least two portions separable in the axial direction, the head comprising a bottom portion connected to the shank and a top portion connectable to the bottom portion, wherein
• the bottom portion defines a socket situated coaxially to the longitudinal axis to accept a driver to rotate the fastener;
• and
• the top portion has an exterior with a convex design and the top portion at least partially covers the socket when the top portion is connected to the bottom portion;
• and
• at least fixation body having at least one bore with a central axis for receiving the bone fastener and defining an bore inner surface, wherein the bottom portion is dimensioned to contact the inner surface at different angles between the longitudinal axis of the shank and the central axis.