| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a polyaxial bone anchoring device. <P>SOLUTION: The polyaxial bone anchoring device includes: an anchoring element having a shaft to be fixed to a bone and a head having a curved outer surface portion; a receiving part having a top end and a bottom end, a channel for receiving a rod, a coaxial bore extending in a direction from the top end to the bottom end, and a seat portion for receiving the head at the bottom end; and a pressure element disposed in the bore and having a head contacting surface portion that contacts with the curved outer surface portion of the head, wherein the head is pivotable with respect to the receiving part and can be fixed at an angle by exerting pressure using the pressure element, and wherein the head has an oversize in the curved outer surface portion with respect to the head contacting surface portion so that an interference fit is achieved that clamps the head by the friction between the outer surface portion and the head contacting surface portion. The curved outer surface portion has the maximum diameter and the head contacting surface contacts with the head in a region including at least the maximum diameter. <P>COPYRIGHT: (C)2012,JPO&INPIT |
