Bone anchoring device

摘要

A bone anchoring device includes an anchoring element having a head, a receiving portion having a first region adjacent to a second end for receiving the head and a recess which is open towards a first end to form two free legs for receiving a rod. The anchoring device further includes a pressure element configured to couple to the head, a first closure element and a second closure element. The first closure element cooperates with the legs to simultaneously fix the rod in the recess and fix the head in the receiving portion, and the second closure element cooperates with the legs, the second closure element acts on the pressure element and on the rod to independently fix the head in the receiving portion and fix the rod in the recess. The first closure element and the second closure element are interchangeable.

主权项

1. A bone anchoring device comprising:
an anchoring dement comprising a shank to be anchored to a bone or a vertebra and a head; a receiving portion comprising a first end and a second end opposite to the first end, a longitudinal axis passing through the two ends, a bore coaxial with the longitudinal axis, a first region adjacent to the second end for receiving said head and a recess which is opened towards the first end and which forms two free legs for receiving a rod, wherein the bore has a first bore region and a second bore region between the first bore region and the first end, the second bore region having a larger diameter than the first bore region such that a shoulder is formed at a transition from the first bore region to the second bore region; a pressure element to exert a pressure on said head to lock said head in the receiving portion, wherein said pressure element has a first end and a second end opposite to the first end of the pressure element, a recess which is open towards the first end of the pressure element to receive the rod, two legs extending towards the first end of the pressure element, and a circumferential projection having an enlarged diameter adjacent the first end of the pressure element; and a closure element configured to engage with said legs of the receiving portion to fix the rod in said recess of the pressure element and fix said receiving portion to the head, wherein the receiving portion has an inner thread from the first end of the receiving portion to a thread end in a direction of the longitudinal axis, and a greatest diameter of the bore at a region adjacent the inner thread is smaller than a greatest diameter of the inner thread, and wherein, when the bone anchoring device is assembled, the closure element is screwed-in between said legs of the receiving portion to fix the rod in said recess of the pressure element and fix said receiving portion to the head, and the thread end is between the first end of the receiving portion and the first end of the pressure element along the direction of the longitudinal axis, and the circumferential projection of the pressure element is in the second bore region.