MedShape Innovates with Nitinol

Atlanta, Ga.-based MedShape Inc., a company that produces shape memory orthopedic devices, has introduced the DynaNail, an intramedullary (IM) ankle arthrodesis nail that contains an 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 not been used clinically due to various technological challenges ranging from basic materials science to manufacturing and device design.

After receiving 510(k) clearance from the U.S. Food and Drug Administration, DynaNail was successfully used in an ankle arthrodesis procedure performed by Doug Pacaccio, D.P.M., at Valley West Community Hospital in Chicago, Ill.

“I was impressed with the performance of the DynaNail device,” commented Dr. Pacaccio, a co-founder of MedShape. “The nail sustains compression across the joint like an external fixator, but because it is inserted like traditional IM nails, it reduces operating time significantly. I believe many podiatrists and orthopedic surgeons will recognize the benefits of the DynaNail device and will incorporate it in their ankle fusion procedures.”

MedShape is working to make DynaNail an effective alternative to external fixators for limb salvage procedures on the merit of nitinol’s compression features. Compression across the joint is important not only for ensuring the joint bones remain in close apposition, but also for promoting healing.

“The nitinol compressive element allows DynaNail the ability to apply sustained compression across the joint on the level of an external fixator,” said Jeremy Blair, team leader for DynaNail. “Traditional nails lose compression upon hardware removal or require follow-up procedures to re-apply compression. Nitinol gives DynaNail ‘shape memory’ so that it can automatically transform and adapt to bone resorption minimizing the need for follow-up procedures.”

The promise of nitinol for orthopedic fixation implants was first identified more than 30 years ago by American metallurgist William Buehler and surgeon James Hughes, M.D., of Johns Hopkins University in Baltimore, Md., in a report to the United States Army. Until now, researchers and companies were unable to transform the alloy into a large commercial orthopedic device due to various engineering challenges. 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 with regulators 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.

“…[W]e are proud of the DynaNail launch and enthusiastic about its efficacy in orthopedic surgery,” said Blair. “Its successful use by Dr. Pacaccio in ankle arthrodesis surgery is a clear indicator of the future it holds for podiatrists and orthopedic surgeons everywhere.”