Patent ID: 8403962
Filing Date: 2013-03-26
Classification: A61B

Abstract:
1. A polyaxial bone screw assembly comprising: a) a receiver defining a central bore and having a top portion and a bottom portion, the bottom portion defining a first recess communicating with the central bore and having a bottom opening, the bottom opening having a diameter; b) a shank having an upper portion and a lower portion for fixation to a bone, the upper portion having an upper surface and a maximum first width smaller than the receiver bottom opening diameter; the shank upper portion including a radially outward extending stop that is sized and shaped to pass through the receiver bottom opening and having a maximum second width; the shank upper portion having a second recess on the upper surface thereof that is sized and shaped to receive a driving tool for operably rotating the shank for installation and removal; c) an independent retaining and articulating structure mateable with the shank upper portion, the retaining and articulating structure having a contact surface configured for slidable engagement with the receiver at the bottom portion defining the first recess; the retaining and articulating structure having a top surface; the retaining and articulating structure being located on the shank upper portion above the stop and having an internal minimum third width less than the stop second width such that the retaining and articulating structure cannot pass the stop and the shank stop operably positions the retaining and articulating structure on the shank and has a lower surface configured to be able to move into the bottom opening with polyaxial motion between the shank and receiver; d) a compression structure insertable in the receiver and pressable against the retaining and articulating structure; and e) the shank, the retaining and articulating structure and the receiver being joinable as a unit wherein, after the shank and the retaining and articulating structure are joined in the receiver, the shank tool receiving second recess on the shank is accessible to the driving tool to allow manipulation of the shank in a patient's bone while the shank is part of the unit.