Design Considerations for Nitinol Bone Staples

The use of Nitinol in orthopedic staples has a long, successful history beginning with their first commercial introduction in the early 1980s. The first Nitinol bone staples were chilled, opened, inserted into predrilled holes, and recovered their shape upon warming to body temperature. More recently, Nitinol bone staples have been introduced which are deployed either superelastically or with the application of an external heat source. These three different design approaches—superelastic, body-temperature recoverable, and heat-activated—each have distinct advantages and disadvantages. This paper will explore the design choices, procedural issues, and potential clinical effects of these three different Nitinol bone staple alternatives, including such factors as ease-of-use, periprocedural stability, control of compression forces, equipment requirements, and length of procedure.