Polyethyl ethyl ketone, commonly referred to as PEEK, is no stranger to the medical device world, and is well vetted in orthopedics. One of the downsides of PEEK, compared to titanium, is its lack of stable bone ingrowth. Companies have tried to augment PEEK with coatings or surface modifications, but those methods haven’t been as widely accepted or as successful as other materials, such as titanium, which traditionally have been better suited to bone ingrowth.
Atlanta, Ga.-based Vertera Spine seems to have developed a way to change that.
The company, which specializes in surface technologies for spine applications, recently received U.S. Food and Drug Administration (FDA) 510(k) clearance for its Cohere Cervical Interbody Fusion Device. Cohere features the company’s PEEK Scoria biomaterial, a proprietary porous surface technology that is based on Zeniva PEEK resin from Alpharetta, Ga.-based Solvay Specialty Polymers. While PEEK implants with porous or rough metal coatings have found their way into clinical use, Cohere is the first FDA-cleared spine device to be manufactured entirely out of PEEK and contain porosity. Solvay Specialty Polymers provides high-performance thermoplastics for use in permanent and prolonged exposure implants as well as limited-exposure devices. The company provides global technical and regulatory support for medical OEMs and processors, and devotes R&D activities to developing novel polymer technology and materials.
Unlike surface treatments that are coated onto a device, Scoria is grown directly out of the solid PEEK Zeniva material, creating a seamless surface-to-solid material interface that company officials claim is more durable than metal coatings and two-times stronger under shear loading than trabecular bone. In addition, because Scoria can be fabricated onto the device without using any additive material, manufacturing costs are lowered compared with metal-coated implants.
Dane Waund, global market manager at Solvay Specialty Polymers, told Orthopedic Design & Technology that the manufacturing process allows implants with this porous technology to be priced competitively with current PEEK device offerings and more cost effective than titanium-coated fusion devices.
PEEK Scoria was developed to address the clinical need for fusion devices that better osseointegrate while still remaining cost-effective. Backed by extensive research at Durham, N.C.-based Duke University and the Parker H. Petit Institute for Bioengineering and Bioscience at Georgia Institute of Technology in Atlanta, Scoria—according to Vertera officials—“represents a breakthrough in how surface technologies are applied to medical devices.”
Privately held Vertera Spine received grant funding from the National Science Foundation and Georgia Research Alliance to help translate its technology portfolio into commercial products.
"The FDA clearance of Cohere represents a significant milestone for Vertera Spine and fusion devices in spine," said Chris Lee, Ph.D., co-founder and CEO of Vertera Spine. "Given the new economics of healthcare, market demands are shifting toward more effective implant technologies at a better price. Cohere, featuring surface porous PEEK Scoria, will be the first in a new generation of biomedical implant innovations to meet this demand."
Studies cited by Vertera highlight the advantages of adding porosity to implant surfaces to form a more stable union with bone.
At the previous two Spine Technology and Educational Group Organization meetings, Frank Phillips, M.D., a founder and past president of the Society for Minimally Invasive Spine Surgery and a member of the Vertera Spine Scientific Advisory Board, delivered a presentation highlighting surface effects on implant integration. Designed to facilitate bone tissue in-growth, Scoria features a fully interconnected pore network with an 300 micrometer (μm) average pore size, more than 500 μm layer thickness, and wettable surface. According to the company, initial pre-clinical testing has demonstrated that bone is able to infiltrate the porous feature and form direct contact with the PEEK Scoria surface. The results, published in Acta Biomaterialia and also presented by Phillips, suggest that the Scoria technology could improve how PEEK devices interact with bone.
"What convinced me of PEEK Scoria's clinical potential were the substantial results compiled from academic research showing that the Scoria surface can effectively osseointegrate with bone and does not have the potential to shear off like titanium coatings," Philips said.
Developed in collaboration with a select team of surgeons, Cohere uses PEEK Scoria to combine the benefits of introducing a porous environment to bone without compromising the mechanical integrity of the implant. Since it is made entirely out of PEEK, Cohere also provides the additional advantage of not producing any medical imaging artifacts, allowing the surgeon to easily assess the fusion site.
“People have been trying to create a porous PEEK for a while—in many different ways, usually a coating or some sort of surface modification,” Lee told Orthopedic Design & Technology. “But it’s important to understand that this isn’t a coating. This is a solid material with porosity.”
Vertera Spine plans to launch Cohere in multiple footprint and height configurations in 2016. Lee said that “down the road” the company also exploring other types of implants, including technology for the lumbar spine.
"Surgeons have been seeking an all PEEK fusion solution that leads to direct bone apposition instead of fibrous encapsulation," said Tim Nash, a Vertera Spine board director who has more than 20 years experience in the spine and orthopedics industries. "Cohere is a game-changing device for spine fusion. By leveraging the performance of the Scoria technology, Vertera Spine will be able to generate a portfolio of implant solutions that were previously not possible."
Solvay's Zeniva PEEK is part of the Solviva Biomaterials lineup, which is offered for use in implantable medical devices. According to Solvay officials, the biomaterial boasts a modulus very close to that of cortical bone plus excellent biocompatibility, toughness and fatigue resistance.
“Vertera Spine’s novel porous surface layer may change the game in how future PEEK-based intervertebral joint fusion devices integrate with bone,” said Maria Gallahue-Worl, global business development manager for Healthcare at Solvay Specialty Polymers. “Also, neither the porosity of PEEK Scoria nor its growth onto bulk polymer is something you can achieve easily with metal solutions or even with many competitive resins. In many ways, this makes Vertera Spine’s application emblematic of the incredible potential that Solvay’s comprehensive line of biomaterials holds for the future of implantable medical device innovation, and it further illustrates the growing momentum behind our advanced materials portfolio.”