Patent ID: 7220263

Claim:
A plate system for immobilizing adjacent vertebral bodies or stabilizing an interbody device, comprising: a plate having at least one opening therein, said at least one opening having an upper section with a pre-selected width w 1 for receiving the head section of a bone screw and a lower section having a width less than w 1 and defining at least a partial helical track through which the threaded end of the screw may be threaded; and a bone screw having a cylindrical head section of diameter d 1 , an intermediate neck section of a diameter d 2 and a depending threaded section of a diameter d 3 , the threaded section having a pitch matching the pitch of the at least the partial helical track in the plate, where d 3 <d 1 , the threaded section of the screw being arranged so that once the screw is threaded completely into the plate opening the screw may be rotated relative to the plate to thread the screw into the vertebral body without causing any axial movement between the screw and the plate and may be removed from the plate only by reversing its rotation into said at least partial helical thread.