A semi-left-hand-thread-removal screw including a screw end head and a bolt, wherein a sink hole is provided on the screw end head, a lower portion of the sink hole is an inscribed polygon structure or an I-shaped structure, a thread which is opposite to the bolt is provided on an upper portion of the sink hole, the inscribed polygon structure is an inscribed hexagon. A screw according to aspects of the disclosure may be screwed in with a common inscribed hexagon screwdriver and an inscribed hexagon structure thereof which are embedded into each other; the screw can be unscrewed with a left-hand-thread screwdriver which is matched with a left-hand-thread structure thereof and screwed in the left-hand-thread structure thereof, after the left-hand-thread screwdriver is screwed in tightly, the screwdriver is continuously co-rotated and then the screw may be unscrewed.

A screw element for the fixation of bone components and bone fragments is disclosed having a shaft with an outside screw thread and a longitudinal axis extending along the shaft and defining a distal direction and a proximal direction, and an insertion direction and an opposite removal direction, and has a tool attachment point starting radially inwards and the tool attachment point has a central opening and in the wall of this opening at least five tooth profiles directed radially outwards and mainly parallel to the screw axis directed radially outwards and mainly parallel to the screw axis are formed in the wall of this opening, and for each tooth profile an insertion wall in insertion direction and a removal wall in removal direction can be separated, and that the surface of the insertion wall is greater than the surface of the removal wall.