Patent ID: 6565567
Filing Date: 2003-05-20
Classification: A61B,Y10T

Abstract:
A pedicle screw assembly for use with a rod for immobilizing bone segments comprising:a pedicle screw having a threaded shaft for insertion into a bone segment and an enlarged generally spherical head; a polyaxial housing having a bore with a longitudinal axis therethrough, for accommodating the passage of the threaded shaft there through, the upper portion of the housing including a pair of internally threaded opposed posts defining an opening substantially perpendicular to the bore axis for receiving the rod, the housing terminating at its lower end in a reduced cross sectional area for engaging the bottom of the screw head along a line circumscribing the generally semispherical bottom surface thereof to retain the screw head within the housing; a washer positioned within the housing between the rod and the top of the screw head, the washer having a generally semispherical roughened bottom surface defined by a plurality of sharp projections; and a set screw for threadably engaging the internally threaded posts to clamp the assembly together, whereby the head of the screw is clamped between the roughened lower surface of the washer and the lower end of the housing.