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Amedica's Momentum Continues

Earlier this year, officials at Salt Lake City, Utah-based Amedica Corp. had a number of items on their to-do list.

Among the goals was to obtain U.S. Food and Drug Administration (FDA) clearance for a second-generation family of cervical and lumbar interbody fusion devices manufactured with the company’s propriety silicon nitride biomaterial. Check.

Another item on the list was to complete studies at Brown University to support the antimicrobial properties of silicon nitride. Done.

“We’re getting it done,” Eric Olson, president and CEO of Amedica told Orthopedic Design & Technology during the recent annual meeting of the North American Spine Society in Dallas, Texas. “It’s been a very busy, but productive year.”

During NASS, Alpesh Patel, M.D., associate professor in the Division of Spine Surgery at the Loyola University Chicago Stritch School of Medicine, presented a poster about the advantages of silicon nitride for use in interbody fusion devices compared to polyetheretherketone (PEEK) and titanium.

The presentation, titled "Decreased Bacterial Count and BioFilm Formation Associated with Silicon Nitride (Si3N4) Materials Used in Interbody Fusion Cages (IBF) Compared to Titanium and Polyetheretherketone (PEEK)," reported on recently published peer-reviewed studies conducted at Brown University that demonstrated silicon nitride's decreased vulnerability to bacterial colonization and biofilm formation in comparison with PEEK and titanium.

Officials for the privately helf firm believe that these attributes will contribute significantly to achieving optimal patient outcomes in clinical applications.

Bryan McEntire, Amedica's chief technology officer, also provided overview of the results of the studies conducted at Brown, and the company's expansion of biomaterial claims for its FDA 510(k)-cleared Valeo interbody fusion devices. Two spine surgeons, Grant Skidmore, M.D., and Mark Crawford, M.D., presented patient case studies using the company’s silicon nitride interbody fusion devices to treat patients suffering from back pain requiring spinal fusion surgery.

“Spine surgeons are increasingly recognizing the value and benefits of silicon nitride for interbody fusion. Material matters and we have scientific, peer-reviewed results that prove silicon nitride's ability to promote bone on-growth and minimize patient exposure to infection risk while increasing the potential for fusion in comparison to PEEK and titanium," said McEntire. "Dr. Skidmore and Dr. Crawford use silicon nitride interbody fusion devices to treat patients and truly understand the vast benefits of our technology.”

In-vitro data from the studies indicate that silicon nitride is far less vulnerable to bacterial colonization (S. epidermidis, S. aureus, P. aeruginosa, E. coli and Enterococcus) than PEEK and titanium. Additionally, because of the positive surface charge, nanostructure and hydrophilic nature of the material, there was also rapid adherence of fibronectin, vitronectin and laminin proteins. which can decrease susceptibility to bacteria and increase osteointegration (bone growth).

In one in-vivo study, the amount of regenerated bone associated with silicon nitride implants was essentially two to three times that of the other two implant materials at three months after surgery. In as little as 14 days, the material demonstrated significantly greater new bone formation at both the surgical site and the implant interface, according to the data.

"Bacterial infection is a serious risk that can lead to non-healing fusions, implant loosening, device failure and, in extreme cases, death," said Dr. Thomas J. Webster, lead investigator, and chair and professor of the Department of Chemical Engineering at Northeastern University in Boston, Mass., at the time the study results were announced. "Selectively engineering the biomaterial or surface structure of the implant can decrease bacterial adhesion, lessening the potential for infection. Our study examined the innate biomaterial characteristics of silicon nitride, PEEK and titanium, and it was evident that silicon nitride holds the greatest potential for decreased risk of bacterial infection."

Surgical site infections are a significant concern for orthopedic surgeons. Bacteria such as methicillin-resistant staphylococcus aureus (MRSA), can initiate severe implant infections and lead to biofilm adhesion. MRSA is difficult to manage clinically due to its high resistance to antibiotics. Biofilm formation or adhesion occurs when free-floating microorganisms attach themselves to the surface of an implant and act as protection for the bacteria. Biofilms often are more resistant to traditional antimicrobial treatments, and can't be treated effectively through antibiotics alone once formed on a medical implant, causing health risks.

Current treatment has focused on surgically removing the infected tissue and implant as well as prolonged antimicrobial therapy. However, as the bacterial strains evolve they form resistances to anti-microbial therapy yielding it ineffective.

According to Olson, silicon nitride has been used in spine applications for more than four years with a “proven record of safety and effectiveness,” adding that he is “incredibly optimistic” about the capabilities of the technology, its future applications and the “ability to rapidly increase sales by demonstrating a clear advantage over PEEK and titanium.”

Following the release of the study findings in early September, on Sept. 27 Amedica received 510(k) clearance from the FDA for its second-generation of cervical and lumbar interbody fusion devices using silicon nitride.

According to the company, the product portfolio expansion offers design enhancements including a threaded insertion feature, additional footprints, and design elements that will allow surgeons to perform minimally invasive and lumbar lateral interbody fusion approaches.

The most common reason for performing a spinal fusion is to eliminate the pain caused by abnormal motion of the vertebrae as a result of diseased discs, slippage of the vertebrae, or other degenerative spinal conditions, and the goal of the procedure is to immobilize the faulty vertebrae themselves.

An interbody fusion device is a prosthesis used in spinal fusion procedures to restore and maintain disc space height following a spinal decompression while fusion occurs. These devices are often filled with bone or other materials in order to promote a spinal fusion at the level that the disc was removed.

Company officials hope that this recent news positions Amedica as a strong competitor in the $1.5 billion IBF market and now allows it to enter the $147 million lateral lumbar interbody fusion (LLIF) segment.

Minimally invasive LLIF procedures may offer improved patient outcomes by allowing reduced operative time, post-operative pain and hospital stays, as well as a rapid return to normal activity. Among the challenges in performing an LLIF procedure is the proximity to nerves during implantation requiring the use of neuromonitoring to ensure precise, safe placement of the implant. Silicon nitride is semi-radiolucent, which enables an exact view of the implant for precise intraoperative positioning, thereby alleviating this challenge.

“Amedica is now better positioned to deliver a technology that can change the standard of care for spinal surgery,” Olson said following the FDA announcement.

During NASS, when asked if who the FDA application process had been, Olson told ODT that the agency was “actually very easy to deal with,” adding that “they understand this technology.”

And let us not forget about the need to keep costs down in healthcare.

With the rules changing for how healthcare facilities are reimbursed for the treatment of hospital-acquired infections, the antimicrobial properties on a material such as silicon nitride could be a “game changer,” McIntire told ODT. “Hospitals are going to be on the hook for preventable infections. And for spinal surgeons, infection can affect 8 to 9 percent of all cases.”

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