A method for osteosynthesis of a spinal column using an assembly including a bone anchor, a connector and a ring, the method comprising: inserting an anchoring part of the bone anchor into bone, the bone anchor including the anchoring part and a head, the head positioned to be in contact with the connector and ring inserting a connecting member into the connector and applying a force to the connecting member such that the connecting member applies the force against the ring and the bone anchor, wherein the head of the bone anchor contacts the connector, ring and connecting member during the application of the force.
