Tightening device for bone fastening cable

Abstract

A bone-tying cable tightening device is disclosed which makes itself unusable after having been used a predetermined number of times. The device includes a grip portion, a rod-like member, a knot-supporting means at the tip, and a cable-holding means to grip and hold the two arms of a cable, and is provided with a sliding block mounted around the rod-like member and connected to a pulling means, and an operation lever, wherein the cable-holding means includes (a) a longitudinal through groove defined in the upper part of the sliding block, (b) a locking recess which extends at the rear end the through groove, either transversing the cross section of the through groove or containing the cross section of the through groove, and whose width in the cross section thereof widens in the rearward direction, and (c) a backward biased locking member which is provided movably back and forth behind the locking recess on the upper side of the sliding block and so made that its forward movement is blocked when it fits in the locking recess, and wherein the device further includes a pull-releasing means which can be operated to release the one-way detent means for the pulling means, and a release locking means to lock the one-way detent means in a released state after the pull-releasing means has been operated a predetermined number of times.