Patent ID: 8840652
Filing Date: 2014-09-23
Classification: A61B

Abstract:
1. A polyaxial bone screw assembly comprising: a) a shank having an elongate body and an upper portion, the body being configured for fixation to a bone, the shank supper portion having a lower neck and an upper region that extends radially outward from the neck and has a lower semispherical surface; b) a receiver having a top portion and a base, the receiver top portion having an upper channel adapted to receive a longitudinal connecting member, the base having an internal seating surface partially defining a cavity, the channel communicating with the cavity, the cavity communicating with an exterior of the base through an opening; the shank upper portion being received through the opening and positioned within the cavity; c) a retainer having an inner surface and an outer surface, the retainer inner surface configured to be in pivotal engagement with the shank upper portion semispherical surface and the retainer outer surface configured to be in engagement with the receiver seating surface when the retainer is captured between the shank upper portion and the seating surface, the retainer preventing the shank upper portion from passing through the receiver opening allowing the shank to move polyaxially relative to the receiver during positioning, the retainer includes two discrete portions that are not joined together.