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 first end and a second end, a channel at the first end for receiving the rod, and an accommodation space for accommodating the head of the bone anchoring element, the accommodation space having an opening for inserting the head at the second end of the receiving part body;
• and
• pressure element comprising a first portion configured to contact the rod and a second portion axially connected to the first portion and having an expandable portion configured to accommodate and clamp the head,
• wherein the pressure element is moveable along a longitudinal axis of the receiving part body from an inserting position to wherein the head is insertable from the opening of the receiving part body into the pressure element, to a pre-locking position wherein the receiving part prevents removal of the head through the opening, and to a locking position to lock the head in the receiving part, and
• wherein when the pressure element is at the pre-locking position, the pressure element engages a portion of an inner wall of the receiving part body that is directed towards the second end of the receiving part body to hold the pressure element against movement towards the inserting position.

A receiving part for receiving a rod for coupling the rod to a bone anchoring element, the receiving part comprising:

• a receiving part body having a first end and a second end, a channel at the first end for receiving the rod, and an accommodation space for accommodating a head of a bone anchoring element, the accommodation space having an opening at a second end of the receiving part body;
• and
• a pressure element comprising a first portion configured to be positioned in the channel when the pressure element is in the receiving part body and a second portion axially connected to the first portion and having an expandable portion defining a hollow section and an opening,
• wherein the pressure element is moveable along a longitudinal axis of the receiving part body from an inserting position wherein at least a part of the expandable portion is positioned in the accommodation space and spaced apart from an inner wall of the receiving part body, to a pre-locking position wherein the expandable portion contacts the inner wall of the receiving part body, and to a locking position wherein the inner wall of the receiving part body urges the expandable portion radially inwards, and
• wherein when the pressure element is at the inserting position, the pressure element engages a first portion of the inner wall of the receiving part body to hold the pressure element against movement towards the first end of the receiving part body, and wherein when the pressure element is at the pre-locking position, the pressure element engages a second portion of the inner wall of the receiving part body that is directed towards the second end of the receiving part body to hold the pressure element against movement towards the inserting position.

A method of coupling a rod to a bone via a bone anchoring device, the bone anchoring device comprising a bone anchoring element having a shaft and a head, a receiving part comprising a receiving part body having a first end and a second end, a channel at the first end for receiving the rod, and an accommodation space for accommodating the head of the bone anchoring element, the accommodation space having an opening for inserting the head at the second end of the receiving part body, a pressure element comprising a first portion configured to contact the rod and a second portion axially connected to the first portion and having an expandable portion configured to accommodate and clamp the head, and a closure element, the method comprising:

• inserting the bone anchoring element into a bone;
• introducing the head of the bone anchoring element through the opening of the receiving part body and into the expandable portion of the pressure element when the pressure element is in an inserting position;
• moving the pressure element along a longitudinal axis of the receiving part body to a pre-locking position, wherein an engagement between the pressure element and a portion of an inner wall of the receiving part body that is directed towards the second end of the receiving part body holds the pressure element against movement back towards the inserting position and the receiving part prevents removal of the head through the opening;
• adjusting an angular position of the receiving part relative to the bone anchoring element;
• 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 further along the longitudinal axis to a locking position, to lock respective positions of the head and the rod relative to the receiving part.