A device for repairing a bone disorder using a polyaxial screw. The device has a pivoted lever mounted rotatably to an extension of a bone screw and which extends essentially at right angles to the longitudinal direction of the extension to which it is mounted and is in contact with a stop on the other extension associated with the vertebral body to be repositioned. The extension that acts on the polyaxial bone screw comprises a longitudinal sleeve, a rod, preferably threaded, extending from within the sleeve and moveable within the sleeve, and a contact surface disposed on the end of the threaded rod which is configured to transmit a force against the bone screw to prevent polyaxial movement of the polyaxial bone screw for as long as the force is transmitted.