System comprising for each vertebra at least one bone anchoring element (10) having an axial part (11) to be anchored into a vertebra (V) and a head (12) pivotally connected to a receiving part (21) which is attached to a hollow threaded elongate member (22) which include two longitudinal slots (24) on opposition allowing insertion there through of a corrective rod (30), being displaceable by means of a threaded pusher wherein the threads (41) of the threaded pusher (40) have a zip configuration with protrusions (46), comprising at least a thread distal portion protruding relative to a thread more proximal portion, said zip configuration being complementary with the threads (25) of the threaded elongated member (22).
