SCHAEDELSCHRAUBE.

摘要

A cranial screw (10) transparent to X-ray or magnetic fields so that it is compatible with CT or MR scanning techniques. The screw (10) has a hollow shank (12) with a threaded distal portion (22) for insertion into a hole in the cranium and an emergency removal drive (14) head spaced proximally from an insertion drive head (16) by a frangible connecting portion (18), so that if excessive torque is placed on the screw during insertion, it will break at the frangible portion (18) leaving the emergency removal drive head (14) and the threaded distal portion (22) intact so that they can be removed using the emergency removal drive head (14).