Abstract: A locking element is configured to be used with a polyaxial bone anchor, and is substantially cylindrical with a bottom side facing a head of the bone anchor, a top side opposite to the bottom side, and a surface portion with an external thread. The locking element has a first recess at the bottom side for accommodating at least a portion of the head, and a second recess at the top side for engagement with a driver. The second recess is located outside the center of the top side. The head has a portion with a largest diameter, and a first level L1 is defined by the highest point of a circle with the largest diameter drawn around the head, and a second level L2 is defined by the bottom of the second recess, L2 being at a level not higher than L1.

Abstract: A bone plate assembly is provided including a plate member with a top side (1a) and a bottom side (1b), at least one hole (2) extending from the top side (1a) to the bottom side (1b), an insert (3) arranged in the hole, the insert having a through hole (31), a guide member (4) removably arranged in the through hole of the insert, the guide member having a guide channel (40) and an outer surface portion (41) which engages an inner wall portion (32) of the through hole (31) to allow a pivoting movement of the guide member within the insert.