Method and tool for assembling a bone anchoring device

A method for assembling a bone anchoring device, the bone anchoring device comprising a bone anchoring element comprising a shaft for anchoring in a bone 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 for accommodating the head of the bone anchoring element in a polyaxial manner, and a locking ring in a first position around the receiving part body, where the locking ring is latched to the receiving part body and in a position in which the head of the bone anchoring element can be introduced into the receiving part body and can freely pivot therein, the method comprising:

• inserting the bone anchoring element in a first holder of a tool and inserting the receiving part in a second holder of the tool;
• actuating the tool from a first configuration towards a second configuration to insert the head of the bone anchoring element into the receiving part body;
• continuing actuation of the tool towards the second configuration to move the locking ring and the receiving part body relative to each other until the locking ring assumes a second position with respect to the receiving part body in which the locking ring is latched to the receiving part body in a position where the looking ring compresses a portion of the receiving part body to compress the head, such that the head is held in and cannot be removed from the receiving part body and the bone anchoring element is held adjustably at a first angular position relative to the receiving part;
• and
• removing the attached bone anchoring element and receiving part from the tool.