Patent ID: 9333011
Filing Date: 2016-05-10
CPC Classification: A61B

Claim Text:
1. A polyaxial bone anchoring device comprising: an anchoring element having a shaft for anchoring in a bone, a head having a curved outer surface portion, and a longitudinal axis extending through the shaft and the head; a receiving part having a top end and a bottom end, a channel for receiving a rod therein, a coaxial bore extending from the top end in a direction of the bottom end, and a seat portion for receiving the head at the bottom end; and a pressure element configured to be arranged within the bore, the pressure element having a head contacting surface portion configured to contact at least a portion of the curved outer surface portion of the head having a greatest width or diameter in a direction perpendicular to the longitudinal axis of the anchoring element; wherein when the head and the pressure element are in the receiving part, the head is pivotable with respect to the receiving part and can be locked at an angle by exerting a downward pressure via the pressure element onto the head to press the head against the seat portion of the receiving part; wherein the greatest width or diameter of the head is greater than a greatest width or diameter of an inner space defined by the head contacting surface portion of the pressure element when the head contacting surface portion is unbiased, such that when the pressure element is in the receiving part and the head is fully inserted in the pressure element, the head biases the head contacting surface portion of the pressure element in a radially outward direction resulting in an interference fit wherein the head is not locked but is prevented from freely pivoting by friction; and wherein the head and the pressure element are movable relative to each other to a plurality of different angular positions, and the interference fit results at each of the plurality of different angular positions before locking the head in the receiving part.