The invention relates to a surgical instrument comprising a bone screw (1) having a screw head (5), and a shaft (2) for rotating the bone screw in a bone, the shaft and/or head forming a single element with the bone screw and having a predetermined breaking point (4). A driving element is inserted into the bone screw by the shaft, said driving element screwing the screw further in or out once the shaft has broken off from the screw.
