Patent ID: 9655652
Date: 2017-05-23
CPC Classifications: A61B

Claim:
1. A bone anchoring device comprising: an anchoring element comprising a shank and a head; a rod; a receiving part configured to pivotably receive the head and to receive the rod for connecting the rod to the shank, the receiving part comprising two legs defining a U-shaped recess, each leg having a free end and an internal thread comprising a plurality of thread turns formed in one-piece with the leg; a filling piece comprising a rod contacting surface configured to correspond with shape of and contact an outer surface of a first portion of the rod, and a second surface opposite the rod contacting surface; a pressure element configured to be arranged its the U-shaped recess and having a seat for receiving the rod, wherein the seat of the pressure element comprises a rod contacting surface configured to face in the direction of the filling piece for contacting a second portion of the rod, wherein a shape of the rod contacting surface of the seat is adapted to the shape of an outer surface of the second portion of the rod, the pressure element having a bore through a central portion of the rod contacting surface of the seat to expose the head of the anchoring element when the pressure element is arranged in the U-shaped recess; a first locking element having a central axis, a solid tubular wall around the central axis and a threaded outer surface on the solid tubular wall configured to engage with the plurality of thread turns of each leg to secure the rod in the seat, the first locking element also configured to contact the pressure element when assembled with the receiving part to secure the head relative to the receiving part; and a second locking element configured to couple to the first locking element and contact the filling piece to secure the rod in the seat of the pressure element, the second locking element comprising an annular surface around the central ax configured to be facing in the direction of the rod when the rod is secured in the seat; wherein the second surface of the filling piece is configured to contact a majority of a width of said annular surface of the second locking element when the rod is secured in the seat, wherein the filling piece is spaced apart from the receiving part assembled in the receiving part with the rod and the pressure element, wherein the filling piece further comprises two opposite outward-facing flat side surfaces extending in a direction of a longitudinal axis of the rod and facing respective opposite inward-facing portions of the pressure element when the filling piece is assembled in the receiving part with the rod and the pressure element, and wherein the rod contacting surface of the filling piece that is configured to contact the rod has a length from a first end to a second end, and a shape of the rod contacting surface of the filling piece from the first end to the second end corresponds to the shape of the outer surface of the rod along a corresponding length of the rod in the direction of the longitudinal axis of the rod such that the rod contacting surface of the filling piece is configured to provide a homogenous load distribution along the corresponding length of the rod.