摘要：

A polyaxial bone anchoring device is provided including an anchoring element (1) having a shank (2) for anchoring in the bone and a head (3), the head having a spherically-shaped outer surface portion (3a); a receiving part (4), the receiving part having a top end (4a) and a bottom end (4b), a central axis (C) extending through the top end and the bottom end, a transverse channel (9) for receiving a rod (100) and an accommodation space (11) for accommodating the head (3), the accommodation space (11) having a lower opening (12) at the bottom (4b), a sleeve-like insert piece (5) encompassing a portion of the head (3) and being configured to pivot in the accommodation space (11) of the receiving part (4), a pressure member (6), the pressure member being arranged at least partially in the accommodation space (11) and wherein the pressure member has a lower surface portion (61) that contacts the head (3) to exert pressure onto the head; wherein the anchoring element (1) is pivotable with respect to the receiving part (4) and can be locked at an angle by exerting pressure with the pressure member (6) onto the head (3) to lock the head and the sleeve-like insert piece (5) simultaneously in the receiving part (4); and wherein the receiving part (4) has a first engagement portion (13) near the bottom end (4b) and the sleeve-like insert piece (5) has a second engagement portion (51) for engaging the first engagement portion (13); and wherein the sleeve-like insert piece (5) is insertable into the accommodation space (11) through the lower opening (12) by advancing it into the accommodation space (11) such that the first engagement portion (13) engages the second engagement portion (51) and after disengagement of the first engagement portion (13) and the second engagement portion (51) the sleeve-like insert piece is freely pivotable in the accommodation space (11).

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