Cancellous Bone Screws - Screws that are characterized by a relatively thin core and a wide and deep thread. They can be fully or partially threaded and vary in size. Fully threaded screws are used for fastening devices such as plates into metaphyseal and epiphyseal areas of bone while partially threaded screws are used as lag screws. Cancellous screws are designed as non-self-tapping screws. Tapping of the cancellous bone is unnecessary because the screw can easily create threads in the soft cancellous bone during insertion. Additionally, its holding power is greater if the threads are not cut because the untapped trabeculae are compressed together as the screw is driven into the bone.