BONE ANCHORING DEVICE

摘要

A bone anchoring device has an anchoring element, a receiving portion, and a pressure element. The anchoring element includes a shank to be anchored in a bone or a vertebra and a head, the head having an exterior surface with a spherical segment-shaped portion. The shank and the head are separate parts. The receiving portion includes a first end, a second end opposite to the first end, a longitudinal axis passing through the two ends, a bore coaxial with the longitudinal axis, and a first region adjacent to the second end for receiving a spherical segment-shaped section of the head. The pressure element exerts pressure on the head to lock the head in the receiving portion. The head has a hollow inner portion to receive a free end portion of the shank and wherein the head and the end portion are formed such that the end portion can be elastically clamped by the head.

主权项

1. A bone anchoring device comprising:
an anchoring element comprising a shank to be anchored in a bone or a vertebra and a head, the head having an exterior surface with a spherical segment-shaped portion, wherein said shank and said head are separate parts; a receiving portion comprising a first end, a second end opposite to the first end, a longitudinal axis passing through the two ends, a bore coaxial with the longitudinal axis, and a first region adjacent to the second end for receiving the spherical segment-shaped section of said head; and a pressure element which exerts pressure on said head to lock said head in the receiving portion, the pressure element being of cylindrical construction and having a spherical recess on a side facing the head, which cooperates with the head when pressure is exerted; wherein said head has a hollow inner portion to receive a free end portion of said shank, wherein said head and said end portion are formed such that the end portion is elastically clamped by said head while the head and end portion are located in the receiving portion and the head and the receiving portion are unlocked to each other, and wherein said end portion is conically shaped, the diameter increasing towards a free end of the shank opposite a second end of the shank.