an apparatus and method for joining members together using a self - drilling screw apparatus or stapling apparatus are disclosed . the screw apparatus includes a shell and first and second first screw members having tapered ends and threaded bodies that are disposed within the shell . a drive mechanism rotatably drives the first and second screw members from the shell in opposite directions and causes the screw members to embed themselves in the members to be joined . the screw apparatus can be used to join members such as bones , portions of the spinal column , vertebral bodies , wood , building materials , metals , masonry , or plastics . the stapling apparatus includes first and second lever arms rotatably joined together at a fulcrum , and the lever arms rotate in opposite directions . first and second cartridges are disposed at the ends of the lever arms . each cartridge is capable of holding a staple including a bracket , a nail member and an alignment slot . when the ends of the lever arms are rotated towards each other the staples from the cartridges are interlocked . the staples can be also be used to join members such as bones , portions of the spinal column , or vertebral bodies .