US Patent 9138274 Fasteners with shape changing bellows and methods using same

A fastening device having a bellows made of a material that changes shape when activated by a catalyst, and having a pleated structure that contracts from an extended state to a contracted state upon activation. The shape changing material may be a shape memory metal alloy, shape memory polymer or elastic memory composite. A method of using this fastener provides apposition and compression of abutment surfaces to join together two pieces of material, and is suitable for joining apposing bone surfaces together to heal fractures via the use of orthopedic hardware.