Receiving part for receiving a rod for coupling the rod to a bone anchoring element and a bone anchoring device with such a receiving part

A bone anchoring device comprising:

• a bone anchoring element having a shaft and a head;
• and
• a receiving part for receiving a rod for coupling the rod to the bone anchoring element, the receiving part comprising:
• a receiving part body having a channel at a first end for receiving the rod, and defining an accommodation space at a second end opposite the first end for accommodating the head of the bone anchoring element;
• a pressure element positionable in the receiving part body, the pressure element comprising a first portion configured to extend into the channel to contact the rod, and a second portion axially connected to the first portion and having a compressible portion, to accommodate and clamp the head;
• and
• a separate ring configured to radially expand and/or compress;
• wherein when the pressure element and the ring are in the receiving part body, the head of the bone anchoring element is insertable into the receiving part, and the pressure element is movable away from the first end of the receiving part body to a pre-locking position wherein the head is restricted from being removed from the receiving part, while the ring forms an abutment restricting movement of the pressure element back towards the first end of the receiving part body;
• and
• wherein the pressure element is movable from the pre-locking position further away from the first end of the receiving part body to a locking position wherein a compressive force is exerted on the compressible portion to lock an angular position of the head of the bone anchoring element relative to the receiving part.

A method of coupling a rod to a bone via a bone anchoring device comprising a bone anchoring element having a shaft and a head, and a receiving part comprising a receiving part body having a channel at a first end for receiving the rod, and defining an accommodation space at a second end opposite the first end for accommodating the head of the bone anchoring element, a monolithic pressure element comprising a first portion configured to extend into the channel to contact the rod, and a second portion having a compressible portion to accommodate and clamp the head, wherein a recess extends circumferentially around an outer surface of the second portion adjacent to the first portion, and wherein an outer diameter of at least part of the second portion increases as the second portion extends away from the first portion, and a closure element, wherein when the pressure element is in the receiving part body, the head of the bone anchoring element is insertable into the receiving part, the method comprising:

• inserting the bone anchoring element into a bone;
• adjusting an angular position of the receiving part relative to the bone anchoring element when the head and the pressure element are in the receiving part body and when the pressure element has been moved to a pre-locking position wherein the head is restricted from being removed from the receiving part while a first surface of the pressure element that faces upwards towards the first end of the receiving part body engages the receiving part body to restrict the pressure element from moving towards the first end of the receiving part body;
• inserting the rod into the channel of the receiving part body;
• and
• advancing the closure element in the channel to push the rod against the pressure element to move the pressure element from the pre-locking position away from the first end of the receiving part body to a locking position wherein a compressive force is exerted on the compressible portion to lock the rod and the angular position of the head of the bone anchoring element relative to the receiving part.