The Super-V Cannula’s Innovative Use of Nitinol

Orthopedic surgeons recognize nitinol as a material with superelastic properties that’s used to make orthopedic staples and implants. The alloy has unique properties that enable it to exhibit excellent shape memory in medical devices.

Arthroscopic Innovations uses nitinol in all of our products, and we’re the first company to utilize the elasticity and shape memory of nitinol for arthroscopic access.

Nitinol is used in the Super-V Cannula to overcome limitations caused by the minimally invasive approach. Specifically:

  • The auto-retracting nitinol fins provide excellent, flexible arthroscopic retraction of the soft tissues
  • When the device is inside the joint, the nitinol walls pinch together for minimal fluid leakage
  • The compressive nature of nitinol allows the outside diameter of the Super V Cannula to be smaller than other cannulas

Development of Nitinol in Commercial Medicine

Nitinol is a nickel-titanium alloy that exhibits shape memory and superelastic properties. The alloy was discovered in 1959 by William Buehler, a scientist from the U.S. Naval Ordnance Laboratory (NOL). The name “nitinol” comes from a combination of the elements it’s made up of (Nickel, or Ni, and Titanium, or Ti) and the group that discovered it (NOL).

The commercial applications of nitinol in medicine increased dramatically after two breakthrough medical devices, Mitek’s Homer Mammalok and the Simon Nitinol Filter, were released in the late 1980’s. Today, the shape-retaining alloy can be found in a plethora of medical devices, ranging from orthodontic archwires and stents to dental drills. 

“Nitinol has become the material for novel medical devices, particularly in the minimally invasive implantable or diagnostic devices and instruments,” writes Xiao-Yan Gong in Nitinol: The Flexible Friend.

The incorporation of nitinol in commercial medical devices is not going away anytime soon. According to a Technavio study reported by BusinessWire, the market for nitinol-based medical devices is predicted to grow at a rate of 11% between 2017 and 2021. What explains this increase in global demand for nitinol-based devices? The “increased efficiency and improved outcomes delivered by nitinol-based devices,” Technavio reports.

“Devices made of Nitinol enable surgeons to achieve complex surgical tasks.”
Chenli Song, in “History and Current Situation of Shape Memory Alloy Devices for Minimally Invasive Surgery"

Nitinol’s Shape Memory Effect

Nitinol, or Nickel Titanium, is a shape memory alloy. Its superelastic and shape memory properties are due to a thermoelastic phase transformation that occurs when the alloy undergoes temperature changes. When the temperature of the alloy is cooled (in what’s known as the martensite phase), it can be molded and shaped. But when the alloy is heated again (in the austenite phase), it returns to its original shape. Nitinol’s shape memory effect is a direct result of this reversible martensitic to austenitic phase transformation. 

Nitinol is also:

  • Biocompatible and non-ferromagnetic
  • Protected from corrosion by a surface layer of titanium dioxide
  • Kink, crush, and fatigue resistant