Abstract: A fastener system for use in reattaching a skull flap in an opening formed in a patient's skull during brain surgery, is simple, quick, and easy to use, and is cost effective. The system includes a fastener element and a substantially disc shaped lock element. Both are made of bio-compatible radiolucent rigid plastic material. The fastener element has a substantially disc shaped head and a shank, the shank having substantially flat first and second substantially parallel surfaces having ratchet teeth on them. The shank typically has a thickness, with ratchet teeth, where it extends through a gap between the skull flap and the skull, of about 1-2 mm. The lock element has a through extending opening defined at least in part by locking teeth which cooperate with the ratchet teeth to allow the lock element to be brought tightly into contact with the skull and skull flap to hold the fastener and lock elements in place and to position the skull flap in the skull.