For decades, foot and ankle surgeons treating patients with complicated comorbidities faced a frustrating reality: Despite considerable surgical effort, patients treated with traditional hindfoot fusion implants frequently experienced nonunions, resulting in potential device fractures, and ultimately yielding disappointing patient outcomes.

In 2005, however, things began to change when MedShape, Inc. (acquired by Enovis Foot & Ankle in 2021 and now part of Enovis’ Trilliant Surgical, LLC business) began developing a fusion nail designed to maintain compression after surgery and adapt to changes throughout the healing process. Drawing on prior academic research, the team recognized NiTiNOL as the key to unlocking this potential.

The Story Behind NiTiNOL

Made from an alloy of nickel and titanium, NiTiNOL was developed in the late 1950’s and early 1960’s by the United States Naval Ordnance Laboratory as part of a program aimed at improving military technologies like missile nose cones. NiTiNOL’s pseudoelasticity enables it to sustain compression, making it an ideal component of an intramedullary nail. However, its benefits had yet to be harnessed well for continuous compression in orthopedic joint fusion.

“People have wanted to use NiTiNOL this way for decades,” says Ken Dupont, Ph.D., Director of Clinical Affairs at Enovis Foot & Ankle. “But we were the first to solve the challenging manufacturing issues in creating complex shapes for device application while maintaining NiTiNOL’s desired properties for our application.”

“I believe many podiatrists and orthopedic surgeons will recognize the benefits of the DynaNail device and incorporate it in their ankle fusion procedures.” - Dr. Paccacio

This understanding led to the creation of DynaNail®, an ankle and hindfoot fusion nail that deploys NiTiNOL’s pseudoelastic properties to maintain post-operative active compression like an external fixator, deliver immediate dynamization, and provide the bending and torsional resistance of a traditional IM nail in complex procedures.

Building the Case for NiTiNOL and the DynaNail® System

An early major milestone for MedShape came in 2011 with a benchtop biomechanical study by Yakacki et al, which showed DynaNail’s sustained compression ability in contrast to the loss of compression observed in competitor static nails.1 This introduced the compression vs simulated resorption “recovery curve”—a visual representation of compression during resorption at the fusion site. Unlike static nails, the NiTiNOL-based construct preserved compression even when large amounts of resorption were simulated, confirming its potential to adapt under long-term challenging physiologic conditions.

Building on this biomechanical study, researchers evaluated how NiTiNOL’s sustained compression capabilities translated into real-world clinical fusion outcomes using the DynaNail system. This phase of validation helped determine if the system’s biomechanical advantage could consistently lead to better results in high-risk patients.

DynaNail’s inaugural surgical use came soon after, performed by Dr. Pacaccio at Valley West Community Hospital in Sandwich, IL.

“The nail sustains compression across the joint like an external fixator, but because it is inserted like traditional intramedullary nails, it reduces operating time significantly,” said Dr. Paccacio. “I believe many podiatrists and orthopedic surgeons will recognize the benefits of the DynaNail device and incorporate it in their ankle fusion procedures.”

In 2015, Foot and Ankle Specialist published the first peer-reviewed clinical paper on DynaNail.2 Led by investigating surgeons Dr. Andrew Hsu, Dr. Samuel Adams, and Dr. Kent Ellington, it described the technology to a clinical audience and showed that DynaNail achieved reliable fusion in complex tibiotalocalcaneal (TTC) fusion cases with historically high nonunion rates.

That seminal study led a wave of peer-reviewed and presented studies further confirming the benefits of sustained dynamic compression for joint fusion, as well as tracking compressive recovery in patients.

In 2019, researchers at Duke conducted a study comparing 50 DynaNail cases to 36 static nail cases.3 They found that despite having more patients with complicating factors typically linked to nonunion (like revision surgery, smoking, or prior trauma), the DynaNail group saw higher fusion rates and a significantly faster time to fusion—36% faster to be exact.

The DynaNail system had surpassed expectations of what a nail can do. Traditional nails lose compression as soon as the installation frames are removed during surgery or need follow-up procedures to restore compression through weight-bearing. In contrast, DynaNail offered a new fusion method by using NiTiNOL to maintain compression across fusion sites.

The Data Backing DynaNail

Simply put, DynaNail was designed to actively support healing in ways that are not possible with static nails. Dozens of studies conducted over the past decade support its consistent performance across high-risk patients and in revision cases. Key findings include:

  • 36% faster time to fusion compared to competitors.3
  • 90+% overall fusion rate compared to 65% in competitor nails.4,5,6,7
  • Successful outcomes in challenging patient populations, including those with diabetes or poor bone quality, tobacco users, and prior nonunions.
  • Repeated high performance in independent studies from leading investigators across the United States.

The Next Chapter of Fusion

The DynaNail story is far from finished, as the technology that made the original system a breakthrough in TTC fusion has since laid the foundation for an entire portfolio of sustained dynamic compression implants.

Today, the DynaNail portfolio includes:

Each of these solutions builds on the original DynaNail concept: to deliver sustained, dynamic compression that supports fusion, even in high-risk cases. As clinical evidence grows, so does our understanding of how dynamic compression improves outcomes. Ongoing research, including studies supported by a Congressionally Directed Medical Research Program grant, continues to explore how DynaNail’s mechanical support influences healing at the cellular level. Advanced imaging and dynamic histomorphometry are uncovering how bone biologically responds to this type of fixation, which has proven to improve fusion outcomes.

In 2020, the Centers for Medicare and Medicaid Services (CMS) introduced new ICD-10-PCS codes for sustained compression internal fixation, based upon submitted biomechanical and clinical performance data on DynaNail and DynaNail Mini, recognizing this technology as a distinct advancement. Today, the DynaNail and DynaClip® device families remain the only devices explicitly listed under these codes, setting them apart in both industry recognition and clinical performance.

A 2025 study using these codes tracked TTC patients treated with sustained compression nails and found significantly higher union rates (94% vs. 83% in the static group, P = 0.002) and a 5% lower complication rate compared to traditional static fixation.7

The DynaNail Difference

More than just a nail, the DynaNail system leverages decades of biomechanical, mechanobiological, and clinical research, as well as innovative material science, to redefine fusion possibilities for patients with limbs otherwise deemed suitable only for amputation. This is what makes DynaNail different.

  1. Yakacki CM, Gall K, Dirschl DR, Pacaccio DJ. Pseudoelastic intramedullary nailing for tibio-talo-calcaneal arthrodesis. Expert Rev Med Devices 2011; 8(2): 159-66.
  2. Hsu AR, Ellington JK, Adams SB, Jr. Tibiotalocalcaneal Arthrodesis Using a Nitinol Intramedullary Hindfoot Nail. Foot Ankle Spec 2015; 8(5): 389-96.
  3. Steele, JR et al. Comparison of Tibiotalocalcaneal Arthrodeses Using a Sustained Dynamic Compression Nail Versus Nondynamized Nails. Foot & ankle specialist vol. 13,3 (2020): 193-200. doi:10.1177/1938640019843332.
  4. Kreulen C, Giza E, Natsuhara K, Ip W. Dynamic Nitinol Compression Versus Static Compression in Tibiotalocalcaneal Nail Fusion, presented at the 2022 Western Orthopaedic Association Annual Meeting; Maui, HI.
  5. Griffin MJ, Coughlin MJ. Evaluation of Midterm Results of the Panta Nail: An Active Compression Tibiotalocalcaneal Arthrodesis Device. The Journal of Foot and Ankle Surgery, 57,1 (2018): 74-80. doi:10.1053/j.jfas.2017.08.010.
  6. Ellington K, Ford S, Kwon J. Tibiotalocalcaneal Arthrodesis Utilizing a Titanium Intramedullary Nail with an Internal Pseudoelastic NiTiNOL Compression Element: A Retrospective Case Series of 33 Patients. The Journal of Foot and Ankle Surgery, 2019; 58(2):266-272. doi:10.1053/j.jfas.2018.08.046.
  7. Chundi G, Dawar A, Ahn DB, Chopra AA, Joshi T, Lin SS, Jones T. Use of Sustained Compression to Mitigate Nonunion in Tibiotalocalcaneal Arthrodesis: A Propensity Score-Matched Nationwide Readmissions Database Analysis. J Am Acad Orthop Surg. 2025 Apr 15. doi: 10.5435/JAAOS-D-25-00011. Epub ahead of print. PMID: 40249946.

*Dr. Pacaccio and Dr. Adams are paid consultants to Enovis™ Foot & Ankle.

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