Importance

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Abstract

A polyaxial bone anchoring device includes an anchoring element having a shaft for anchoring in a bone and a head, a receiving part having a first end and a second end, a channel for receiving a rod therein, a bore extending from the first end to the second end, and a seat for receiving the head, a pressure element configured to be arranged in the bore and to exert pressure onto the head when the head and the pressure element are in the receiving part, wherein the head is pivotable and can be locked at an angle relative to the receiving part by the pressure element, wherein an outer wall of the pressure element has one of a recess or a deformable portion, and an inner wall of the receiving part has the other one of a deformable portion or a recess configured to be positioned corresponding to the recess or deformable portion of the pressure element, wherein when the head and the pressure element are in the receiving part, the pressure element is movable from a first position wherein the deformable portion protrudes a first distance into the recess and engages the recess while the head is pivotable relative to the receiving part, to a second position wherein the deformable portion protrudes a second distance greater than the first distance into the recess and engages the recess, where the pressure element is closer to the second end of the receiving part in the second position than in the first position, such that a force is exerted by the pressure element onto the head that holds the head at one of a plurality of releasable angular positions relative to the receiving part by friction before locking the head in the receiving part.

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First Claim