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 threaded 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 comprising a rod receiving portion with a channel for receiving the rod, and a head receiving portion for accommodating the head of the bone anchoring element, the head receiving portion having an open end and being flexible for inserting and clamping of the head;
• a locking ring around the head receiving portion to exert a first force onto the head receiving portion to lock the head therein when the receiving part is in a locking position;
• and
• a pre-locking ring separate from the locking ring and around the head receiving portion to exert a second force less than the first force onto the head receiving portion to clamp the head when the receiving part is in a temporary pre-locking position different from the locking position.

A method of coupling a rod to a bone anchoring element via a receiving part, the receiving part comprising a receiving part body comprising a rod receiving portion with a channel for receiving the rod and a head receiving portion having an open end and being flexible for inserting and clamping of a head of the bone anchoring element, a locking ring around the head receiving portion, and a pre-locking ring separate from the locking ring and around the head receiving portion, the method comprising:

• introducing the head of the bone anchoring element into the open end of the head receiving portion;
• mounting the pre-locking ring around the head receiving portion, wherein the pre-locking ring exerts a first force onto the head receiving portion to clamp the head and to temporarily hold a position of the receiving part relative to the bone anchoring element when the receiving part is in a pre-locking position;
• pivoting the head receiving portion relative to the head to align the receiving part with the rod;
• inserting the rod into the channel of the rod receiving portion;
• advancing a closure element in the channel to push the rod against the locking ring;
• and
• further advancing the closure element in the channel towards the head receiving portion to force the locking ring towards the open end of the head receiving portion via the rod to adjust the receiving part to a locking position different from the pre-locking position, wherein the locking ring exerts a second force greater than the first force onto the head receiving portion to lock the position of the bone anchoring element relative to the receiving part.