Coupling assembly for coupling a rod to a bone anchoring element, kit of such a coupling assembly different rod receiving elements and bone anchoring device

[0050]In FIGS. 1 and 2, a bone anchoring device includes a bone anchoring element 1 in the form of a bone screw having a shank 2 that is at least partially provided with a bone thread and a head 3. The head 3 has a spherical segment-shaped outer surface portion including a greatest outer diameter E of the sphere and a flat free end with a recess 4 for engagement with a screwing-in tool.

[0051]The bone anchoring device further includes a coupling assembly 5 for receiving a stabilization rod 100 and for coupling the stabilization rod 100 to the bone anchoring element 1. The coupling assembly 5 includes a receiving part 6 for receiving the head 3 of the bone anchoring element 1 and for receiving the rod 100, a pressure element 7 configured to be arranged in the receiving part 6 and a rod receiving element 8 also configured to be arranged in the receiving part 6. The pressure element 7 serves for locking the head 3 in the receiving part 6. The rod receiving element 8 serves for receivin...

[0088]the coupling assembly is described with reference to FIG. 30. FIG. 30 shows the bone anchoring device with the anchoring element 1, the rod 100 and the locking element 10 as in the previous embodiments. The pressure element 700 differs from the pressure element of the previous embodiments in that it is free from a deformable portion that cooperates with the rod receiving element and does not have the annular projection for connecting it in an interference-fit manner to the rod receiving element. Instead of this, the pressure element 700 comprises a non-deformable annular projection 790 with a flat upper surface 790a that cooperates with a collar-like conically widening projection 890 at the second end of the rod receiving element 800. The collar like projection 890 has a substantially inverse shape compared to the collar 79 as described in the previous embodiments. It is slightly flexible when it engages the flat upper surface 790a of the pressure element 700 when a load acts ...