Superelastic Nitinol Technology Supports Subtalar Fusion

An innovative orthopedic device designed specifically for subtalar fusion maintains active compression post-surgery to promote healing and joint stability.

The MedShape (Atlanta, GA, USA) DynaNail Mini Fusion System features an internal superelastic nickel titanium (Nitinol) compressive element that provides dynamic compression in order to facilitate healing in the fusion site. During the surgical procedure, the compressive element is held in the stretched, activated position and fixed into position with transverse screws into the talus and calcaneus bones. Subsequently, it recovers its passive length in response to bone resorption or settling, allowing for compression to be maintained throughout the healing process.


Manual compression can also be applied during surgery via the proprietary Mini Targeting Frame, which ensures tight bone apposition immediately post-surgery. The Mini Targeting Frame, which is made of a blend of carbon-fiber and polyetheretherketone (PEEK), also features a robust, universal one-arm design that allows for reliable drilling and screw placement. The DynaNail Mini is supplied with the compressive element pre-stretched on a disposable nail guide attached to the Targeting Frame, thereby reducing the number of steps in the operating room (OR).

“As a market leader in Nitinol devices, we are proud to provide another novel solution that surgeons can add to their arsenal of surgical tools to address challenging pathologies,” said Kurt Jacobus, CEO of MedShape. “Early successful outcomes observed with the DynaNail Mini further validate the expansion of the DynaNail technology to other foot and ankle and trauma fusion applications. We are excited to see what the future holds.”

“I was initially attracted to the DynaNail due to its excellent post-operative compression, particularly in patients with poor bone quality and in more complex cases,” said Terrence Philbin, DO, of Orthopedic Foot & Ankle (Columbus, OH, USA), who was one of the first users of the DynaNail Mini. “From my experience so far, I have found the Mini nail to be easy to use and the results reproducible across my patient population.”

Nitinol is a metal alloy of nickel and titanium (in roughly equal atomic percentages), which exhibit two closely related and unique properties. The first is shape memory, which refers to its ability to undergo deformation at one temperature, then recover its original, non-deformed shape upon heating above its transformation temperature. The second is superelasticity, which occurs at a narrow temperature range just above transformation temperature; in this case, no heating is necessary to cause the non-deformed shape to recover.

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