Patent ID: 9597121
Date: 2017-03-21
CPC Classifications: A61B,F04C

Claim:
1. A polyaxial bone anchoring device comprising: a bone anchoring element having a head and a shaft for anchoring to a bone; a receiving part for coupling the bone anchoring element to a rod, the receiving part having a first end and a second end, a head receiving portion at the second end with an accommodation space for accommodating the head, and a rod receiving portion at the first end, the rod receiving portion having an inner wall defining a bore, the bore having a bore axis; and a pressure member movable in the bore and comprising a first section defining a first surface for engaging the head, and a one-piece second section that is axially connected to the first section and that defines both a second surface for engaging the rod and an outer surface; wherein when the bone anchoring element and the pressure member are in the receiving part, the pressure member is configured to assume and be held at a first position where friction between the first surface and the head generates a preload on the head to maintain the shaft at a temporary angular position relative to the receiving part, and a second position different from the first position where the head is locked relative to the receiving part; and wherein when the pressure member is at the first position, a portion of the inner wall of the receiving part that is directed towards the bore axis exerts a holding force on the outer surface of the pressure member to restrict movement of the pressure member towards the first end of the receiving part, and wherein the pressure member is movable out of the first position towards the first end of the receiving part by applying a sufficient axial force on the pressure member.