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 having 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;
• and
• a locking ring around the head receiving portion,
• wherein in an insertion position of the locking ring, the head is insertable into the head receiving portion,
• wherein in a pre-locking position of the locking ring, a spring portion on one of the locking ring or the receiving part body engages a corresponding portion on the other one of the locking ring or the receiving part body, forming a stop that restricts the locking ring from assuming the insertion position, and the locking ring exerts a first force onto the head via the head receiving portion to maintain a temporary angular position of the bone anchoring element relative to the receiving part body,
• wherein in a locking position of the locking ring, the locking ring exerts a second force greater than the first force onto the head via the head receiving portion to lock the angular position of the bone anchoring element relative to the receiving part body.

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 having a channel for receiving the rod and a head receiving portion for accommodating a head of a bone anchoring element, the head receiving portion having an open end and being flexible for inserting and clamping of a head of the bone anchoring element, and a locking ring around the head receiving portion of the receiving part body, the method comprising:

• introducing the head of the bone anchoring element into the open end of the head receiving portion when the locking ring is in an insertion position;
• advancing the locking ring relative to the head receiving portion to a pre-locking position wherein a spring portion on one of the locking ring or the receiving part body engages a corresponding portion on the other one of the locking ring or the receiving part body, forming a stop that restricts the locking ring from returning to the insertion position, where the locking ring exerts a first force on the head via the head receiving portion to maintain a temporary angular position of the bone anchoring element relative to the receiving part;
• pivoting the receiving part relative to the bone anchoring element 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 toward the head receiving portion to further advance the locking ring relative to the head receiving portion to a locking position via the rod, where the locking ring exerts a second force greater than the first force on the head via the head receiving portion to lock the angular position of the bone anchoring element relative to the receiving part.