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A bone screw 104 is a type of screw adapted for use with implants in, on, or in connection with, parts of the body of a patient. As used herein, a "screw" refers to a type of fastener characterized by a helical ridge, known as a male thread (external thread). Screws may be made from a variety of materials including metal, plastic, composite materials, natural materials, or the like. Screws can be used to fasten materials by the engagement of the screw thread with a similar female thread (internal thread) in the matching part. Screws can also be self-threading (also known as self-tapping) where the thread cuts into the material when the screw is turned, creating an internal thread that helps pull fastened materials together and prevent pull-out. There are many screws for a variety of materials; those materials commonly fastened by screws include wood, sheet metal, and plastic. (Search "screw" on Wikipedia.com Apr. 6, 2021. Modified. Accessed Apr. 20, 2021.) A screw generally includes a head connected to a shank. The helical ridge extends from the shank.

Added by DJM 5 2021