Abstract: The invention provides apparatuses and systems for cutting off electromagnetic radiation (ER) beams, such as laser beams. The apparatuses and systems employ gravitational force on a shutter to close off the path of the ER beam if power is cut to an electromagnet holding the shutter out of the beam path. Power to the electromagnet is typically connected to a safety interlock connected to a door or other entry point to an enclosure in which the ER beam is being used. Additionally, the invention provides add-on devices that allow the ER beam to be blocked to change lenses or targets.

Abstract: A surgical screwdriver for inserting bone screws in bone tunnels in ligament reconstruction has, in a preferred embodiment, a cannulated flexible shaft portion. The flexible shaft portion is formed by a plurality of linkage members disposed in series. Each linkage member is joined to an adjacent linkage member so as to permit adjacent linkage members to be pivotally movable with respect to one another about a pivot axis. The screwdriver is used in methods of arthroscopic cruciate ligament reconstruction including the steps of introducing the screwdriver along a guide wire through a portal that is offset from the longitudinal axis of a bone tunnel and driving an interference screw mounted on the driver in the bone tunnel to fixate a bone block in the bone tunnel.