Patent ID: 7699881

Claim:
A bone screw comprising: an elongated cylindrical shank having a free end and at an opposite end a screw head; a screwthread extending generally helically along the shank from the free end toward the screw head and itself having a first screwthread portion extending from the free end toward the screw head, comprising three turns, and forming a generally continuous and smooth cutting edge, a second screwthread portion extending from the first portion toward the screw head and formed of a plurality of turns each formed with at least one respective outwardly open recess, the recesses being of increasing angular dimension away from the free end, and a third screwthread portion extending from the second portion to the screw head and formed of a plurality of turns each formed with three outwardly open recesses equispaced every 360°, all of the recesses of the third portion being of generally the same angular dimension.