MedShape Reports DynaNail Successful in High-Risk Patients

MedShape Inc., a developer of shape memory orthopedic devices, reported on the first wave of clinical outcomes in patients who have received the company’s DynaNail TTC fusion System. To date, during its targeted soft launch period, DynaNail has been successfully implanted in more than 100 tibiotalocalcaneal (TTC) fusion procedures (which fuses the shin bone [tibia] to the main bones in the back of the foot [talus and calcaneus]), according to the company.

Because the internal nickel titanium (nitinol) element maintains the target fusion bones in close apposition and under sustained compression, fusions are being observed with the DynaNail TTC Fusion System in high-risk patients, specifically those who require bone allografts.

Since its introduction in October 2012, DynaNail has been used to address a number of different pathologies, including Charcot neuroarthropathy, severe ankle and subtalar osteoarthritis, failed total ankle replacement and non-union following a previous arthrodesis (the surgical fixation of a joint, ultimately resulting in bone fusion) procedure. In many of these patients, a bone allograft was used in combination with DynaNail to fill large bony defects and/or replace a fractured or missing talus.

Achieving fusion using an allograft has previously proven challenging, particularly in high-risk patients with degenerative bone conditions or who are immuno-compromised. A 2013 study published in Foot & Ankle International reported a 50 percent non-union rate in patients who underwent TTC fusion when an allograft was used and no fusions when the graft was used on diabetic patients.

However, a large number of high-risk patients have experienced fusions with DynaNail, as confirmed by CT scan, including many with bulk allografts.Thomas San Giovanni, M.D., of the UHZ Sports Medicine Institute in Coral Gables, Fla., has implanted DynaNail in five patients, using a femoral head allograft for three, and has reported successful fusion in each.

“I believe we may be entering a new era within orthopedics where the unique properties of certain materials such as nitinol will be used to our advantage to assist in the healing of bone—complementing both the mechanical and biologic nature of bone healing,” said San Giovanni. “The DynaNail is the first product of its kind and certainly is on the brink of this technology. I’ve had very good success with the DynaNail in some of the most difficult clinical scenarios where combined arthrodesis of the ankle and subtalar joint was needed. It has become my preferred fixation method when using a nail for TTC fusions. I have been very impressed by its performance and foresee the technology and unique properties of this nail lending itself to many future applications, even for other conditions.”

Eric Giza, M.D., at the University of California Davis in Sacramento, Calif.,also has used DynaNail in three TTC fusion procedures. In his first case he used a fibular autograft, and for the second case he implanted a synthetic trabecular metal spacer due to severe bone loss. At four months, there is evidence of fusion for both patients while the third patient is still outside the fusion window.

“I have found that the maintenance of compression from DynaNail has led to impressive stability for complex cases,” Giza said.

DynaNail is the only TTC fusion device to harness the elastic properties of nitinol, according to company officials. Its internal nitinol element allows for compression to be maintained across the joint post-operatively by automatically adapting to loading changes due to settling or resorption. Samuel Adams, M.D., from Duke University in Durham, N.C., first used DynaNail based on its sustained compressive power. Adams has implanted DynaNail in five patients, all using a bone allograft.

“The DynaNail is an unrivaled orthopedic device and my implant of choice for hindfoot arthrodeses,” said Adams. “No other hindfoot fusion device allows for intraoperative compression and accounts for postoperative bone resorption through sustained dynamic compression. It’s amazing to ‘see’ the DynaNail at work.”

Compression across the joint is important for not only ensuring the bones remain in close apposition, but also in promoting healing. According to Daniel Latt, M.D., from the University of Arizona in Tucson, Ariz..

“The DynaNail is the perfect alternative to a multiplanar external fixator in the treatment of failed hindfoot fusion,” Latt said. “It is the only internal device capable of generating continuous compression to stimulate growth of the fusion mass.”

Latt has performed four TTC fusions using DynaNail, all in combination with a cancellous bone allograft. Three patients have shown evidence of fusion at three months post-operation while the fourth patient is still in the early stages of recovery.

The DynaNail TTC Fusion System will be available for full release beginning in January 2014.

Atlanta, Ga.-based MedShape is a privately held medical device company that develops surgical solutions that use its patented shape memory technologies in the sports medicine, joint fusion, and musculoskeletal trauma markets.