Abstract: The outer periphery of a head section (11e) of a medical screw (11) is provided with an inverse external screw thread (11h) that is formed in the opposite screw direction from that of a screw thread (11b) provided to a tip section (11a). An inverse internal screw thread (14a) provided to the leading end of a rod-shaped body constituting an extraction jig (14) is rotated in the opposite direction from the screw direction of the screw thread (11b) so as to be screwed onto the inverse external screw thread (11h) and thereby integrate the screw (11) and the extraction jig (14). The screw (11) is gently extracted from the bone fracture site (D) and is removed from the body by rotating the extraction jig in the reverse direction from the insertion direction of the screw (11).

Abstract: A graduated guide pin for selecting a screw for connecting a fractured bone is formed by a pin-like main body 11 of a radiotransparent metal and ring-like members 12 of a radioopaque metal. The ring-like members are arranged on an outer surface of the main body such that successive members are separated from each other by a distance equal to that of the ring-like members. On an X-ray image, by counting the number of dark portions corresponding to the ring-like members, a length of the fractured bone is measured, and a screw 20 having a suitable length is selected.