Coupling assembly for coupling a rod to a bone anchoring element and bone anchoring device with such a coupling assembly

摘要

A coupling assembly for coupling a rod to a bone anchoring element includes a receiving part with an accommodation space defining an opening for inserting and accommodating a head of the bone anchoring element, and a pressure element having a cap portion configured to hold the head. In an inserting position, the cap portion of the pressure element is expandable in the accommodation space of the receiving part, and a first retaining element is configured to prevent the pressure element from moving towards a first end of the receiving part. In a pre-locking position, the head is held in the cap portion of the pressure element and is pivotable in the receiving part, while the cap portion is restricted from expanding to prevent removal of the head, and where a second retaining element is configured to prevent the pressure element from moving from the pre-locking position towards the inserting position.