MedShape, Inc. has announced the introduction and first surgical use of the DynaNail Ankle Arthrodesis Nail, an intramedullary (IM) nail that contains an innovative internal nickel titanium (NiTiNOL) element. The product is the first IM nail to harness the shape memory properties of NiTiNOL, which up to now has been impeded from clinical use due to various technological challenges ranging from basic materials science to manufacturing and device design.
“The NiTiNOL compressive element allows DynaNail the ability to apply sustained compression across the joint on the level of an external fixator. Traditional nails lose compression upon hardware removal or require follow-up procedures to re-apply compression, ” said Jeremy Blair, team leader for DynaNail, in the November 14, 2012 news release. “NiTiNOL gives DynaNail ‘shape memory’ so that it can automatically transform and adapt to bone resorption minimizing the need for follow-up procedures.”
According to MedShape, the use of NiTiNOL for orthopedic fixation implants was first identified more than 30 years ago by American metallurgist William Buehler and surgeon Dr. James Hughes of Johns Hopkins in a report to the United States Army. Until now, researchers and companies were unable to translate the alloy into a large commercial orthopedic device due to challenges across various engineering disciplines. As a result, NiTiNOL’s use in orthopedic implants has been limited to small staples and suture anchors, neither of which fully harnesses the capabilities of the alloy. In addition to patenting a new surgical method to activate NiTiNOL inside the body across fracture and fusion sites, scientists at MedShape developed and cleared a new NiTiNOL material, one that facilitates machining into complex geometries necessary to integrate the NiTiNOL into a titanium platform. The combination of the titanium and NiTiNOL provides the rigidity of traditional IM nails in bending and torsion with the axial compressive power of an external fixation frame.
Asked what issues had to be overcome, Blair told OTW,
The primary issues were: (1) making an alloy that was readily machinable into complex geometries using conventional machining; (2) finding a surgical procedure (now patented) for activating NiTiNOL inside the body across fusion/fracture joints; (3) combining NiTiNOL with titanium in a way to harness the best of both materials.
Blair added, “Our next steps are to continue ramping up the DynaNail launch, including expanded size offerings, leading up to a full launch at the annual AAOS [American Academy of Orthopaedic Surgeons] meeting in Chicago. MedShape will then follow up with several NiTiNOL-based devices, currently in development.”
