Patent ID: 8506601
Filing Date: 2013-08-13
Classification: A61B

Abstract:
1. A pedicle screw assembly for securing a spinal rod to a vertebral bone, the pedicle screw assembly comprising: a coupling device configured for receiving a spinal rod seated therein and having a central axis with the spinal rod extending generally orthogonal to the central axis when seated in the coupling device; a through passageway of the coupling device extending along the coupling device central axis; an elongate screw anchor member having proximal and distal ends, an elongate threaded shank portion configured for being rotated to be anchored to a vertebral bone, a central longitudinal axis extending along the elongate threaded shank portion and about which the elongate threaded shank portion is rotatable for being driven into a vertebral bone, and an enlarged, generally spherical head portion at the screw anchor member proximal end and having a center; a bottom opening of the coupling device through passageway; an engagement surface of the coupling device for engaging the screw anchor member head portion with the screw anchor member extending out of the bottom opening for anchoring the elongate threaded shank portion thereof to a vertebral bone; and a non-threaded neck portion of the elongate screw anchor member connected to the enlarged head portion and the elongate shank portion to extend therebetween and having a central axis extending therealong obliquely to the threaded shank portion central longitudinal axis so that the enlarged head portion is proximally spaced from the elongate threaded shank portion and the center thereof is offset from the shank portion central longitudinal axis to allow the coupling device to be pivoted toward the elongate shank portion by a greater amount in one direction than in an opposite direction and to allow for 360° relative rotation between the coupling device and the screw anchor member head portion so that the greater amount of pivoting between the coupling device and the elongate shank portion in the one direction is accessible by relative rotation, if necessary, between the coupling device and the screw anchor member head portion, wherein the generally spherical enlarged head portion of the elongate screw anchor member has a truncated upper portion in which a drive recess is formed and has an axis extending centrally through the drive recess and the enlarged head portion center that is offset and generally parallel to the threaded shank portion longitudinal axis due to the obliquely extending neck portion therebetween, and wherein the generally spherical enlarged head portion of the screw anchor member has one spherical surface portion along one side thereof that extends to and between the truncated upper portion and the anchor member neck portion in a proximal-to-distal direction down along the one side of the generally spherical enlarged head portion for a longer distance than a diametrically opposite spherical surface portion along a diametrically opposite side of the generally spherical enlarged head portion with the opposite spherical surface portion extending to and between the truncated upper portion and the anchor member neck portion in the proximal-to-distal direction down along the opposite side of the generally spherical enlarged head portion.