As materials specialist Victrex celebrates the 40th Anniversary of PEEK, Invibio is making significant progress with its implantable PEEK, providing non-metal solutions for implantable medical devices. MPN recently had the opportunity to talk to John Devine PhD, Business Director at Invibio Biomaterial Solutions, to assess that progress.
JUVORA implant prosthetic framework
In 1978, PEEK (polyetheretherketone), a member of the PAEK (polyaryletherketone) family of high-performance polymers, was invented. Beyond the tongue twisting names are materials with significant properties. These exceptional polymers have come to play an important role in replacing metal within several sectors, including automotive, aerospace and energy. The first commercialisation of the new polymer came in 1981, in the form of Victrex PEEK. In 1993, a company called Victrex was formed around these polymers, focusing on the development of the PAEK family, and in particular PEEK – new materials that clearly had an enormous potential.
The focus sectors now include the medical field. In 1999, PEEK-OPTIMA Natural was launched as the world´s first implantable PEEK polymer, which resulted in the manufacturing of an intervertebral cage – in other words, a spinal implant. The rest, as they say, is history. That spark of innovative genius was instrumental in the formation of Invibio Biomaterial Solutions in 2001. Operating as a division within the Victrex group of companies today, Invibio continues to actively pursue R&D and forge partnerships as it develops the potential of PEEK as an alternative to metal in spinal fusion, trauma, orthopedics (total knee replacement) and even dental prosthetics. Today, Victrex and Invibio remain ardent pioneers of PEEK, with a long track record of impressive achievements.
MPN: PEEK's 40th anniversary seems a good time to assess the impact of the high-performance polymer on the medical field. We know that Invibio’s PEEK is now being used to make implantable medical devices, for example. What are your thoughts on the future of PEEK as a material for medical implants?
JD: Over the last 15 years we have made enormous progress in the use of PEEK-OPTIMA-based solutions for medical implants, and we are absolutely sure this will continue to be the case. In spinal fusion, our PEEK-OPTIMA Natural has become one of the leading interbody fusion (IBF) biomaterials. Today, its many advantages, including a modulus similar to cortical bone, as well as radiolucency for artefact-free imaging, are maintained with PEEK-OPTIMA HA Enhanced, where hydroxyapatite (HA), a well-known osteoconductive material found within bone, is fully integrated, encouraging bone ongrowth.1
Similarly, for the treatment of trauma, Invibio has developed PEEK-OPTIMA Ultra Reinforced, which combines the mechanical properties of PEEK-OPTIMA Natural with the additional strength imparted by continuous carbon fibres. Compared to metals typically used in anatomic trauma plates, PEEK-OPTIMA Ultra-Reinforced may offer earlier and greater callus formation for improved secondary bone healing,2 greater material fatigue life allowing healing to occur before the implant fails,3 and all the advantages of radiolucency for 360° fracture visibility during and after the procedure.
The PEEK-OPTIMA Knee Implant, meanwhile, has the potential to offer surgeons an alternative to metal implants for total knee replacement (TKR). Together with Maxx Orthopedics, we are progressing this program and fully expect it to contribute, in the long term, to improved operative procedures and economic and patient outcomes, with the potential to improve the patient's quality of life.
Our vision for the future also includes the potential use of additive manufacturing techniques in the production of medical implants using PEEK OPTIMA. Victrex, our parent company, is currently cooperating with Exeter University in the development of VICTREX PAEK polymers for 3D printing processes and recently announced a high-strength PAEK-based material for laser sintering (LS), plus a filament with better Z-strength than existing PAEK materials and better printability for filament fusion (FF), although these are not currently available for use in medical implants.4
MPN: The use of PEEK in medical applications was perhaps an unexpected development. What has driven these breakthroughs?
JD: Initially, the medical adoption of PEEK may have been motivated by its flexibility – it has a modulus closer to that of bone. It is not excessively stiff, unlike many metals, and perhaps this suggested the possibility of PEEK as a biomaterial. That it is also radiolucent and provides artifact-free imaging, while metals do not, could have been another compelling point of interest for researchers. That PEEK is chemically inert and a biocompatible polymer also strongly supports the possibility of its use for medical implants.
Forming Invibio in 2001 to focus on the medical field and achieving the first ISO compliances in 2003 and accreditation to ISO 17025:2005, in 2014, probably reinforced Invibio’s standing as a pioneering, reliable R&D partner. In addition, we opened a dedicated Global Technical Centre in the UK, in 2007. The centre houses processing facilities, testing laboratories and a Class 10,000 clean room, ensuring contaminate-free manufacturing capabilities for research and development grades as well as prototype materials and application components.
Over two decades, Invibio has successfully progressed the use of implantable PEEK, evolving, in the process, from a materials supplier to an industry-leading provider of PEEK-OPTIMA-based biomaterial solutions. We have commenced work with world-class research institutions, and leading HCPs, to develop and commercialise six implantable PEEK grades, based on supporting data obtained from clinical studies. Today, some nine million devices manufactured from PEEK-OPTIMA polymers have been implanted worldwide.5
MPN: Can you highlight two or three clinical results that have unequivocally demonstrated positive patient outcomes?
JD: A summary of peer-reviewed published literature showed that the clinical history of PEEK in interbody fusion indicates that among comparative cervical interbody studies, fusion rates range from 88-100% for PEEK-OPTIMA Natural, while 47-93% fusion is achieved with titanium cages.6.7.8 Subsidence rates range from 0-14% of levels for PEEK-OPTIMA Natural, whereas it has consistently been reported as higher in titanium cage groups, from 16-20%.6.7.8.9 Odom criteria was available for three of the studies, demonstrating good or excellent outcomes in 64-80% of the patients receiving PEEK-OPTIMA Natural cages compared with 55-75% of patients receiving titanium cages.7.8.9
Cranio-maxillofacial studies have been conducted, on embedded cranioplasty (CP) and covered cranioplasty. In one study, including 185 patients, the reoperation rate was lower (1.3%) and brain function improvement was higher (25.3%) with PEEK compared to titanium, where there was a high patient reoperation rate (10%) and lower brain function improvement (10.9%).10
In 2017, Alex Jahangir, MD presented results for a study using continuous carbon-fibre reinforced PEEK (CFR-PEEK) plates in the treatment of distal femur fractures.11 Distal femur fractures are most commonly treated with stainless steel (SS) or titanium lateral locked plating. CFR-PEEK plates are an alternative fixation, with a potentially higher fatigue strength compared to metal implants3 and a modulus of elasticity close to that of cortical bone. In a study of 38 patients, with an average age of 54 years, CFR-PEEK plates showed a similar time to radiographic union and full weight bearing as SS plates, with no hardware failures, reoperations, or non-unions in short-term follow-up. In contrast, while the patient population receiving SS implants was healthier, not all patients healed and plates broke. These data suggest that CFR-PEEK plates may be a viable alternative to SS plates in the fixation of these fractures11.
I think that these are three compelling examples of positive patient outcomes where PEEK-OPTIMA-based implant solutions have been applied.
MPN: Despite a wealth of increasingly convincing clinical evidence that PEEK-based devices can result in more favourable patient outcomes, metal implants remain the first port of call in many, if not the majority of cases. What challenges are you facing?
JD: Invibio is attempting an enormous sea-change, as we develop and supply PEEK-based devices. In this situation, progress is understandably gradual. Across all industries, driving innovation is challenging, but even more so in the medical field, for a variety of reasons. This applies in particular to the smaller makers of medical devices, who may not have the resources to support sufficiently large and long-term clinical studies. This is where Invibio can perhaps assist through some form of collaborative arrangement.
The social phenomenon of the diffusion and adoption of technological innovation is an interesting one. It's been observed that the early adopters of innovative technologies and products are a minority. The vast majority in the community are slow to adopt change, even when it is clearly for the better. In the medical field, that's compounded with the risk factors that are involved with the adoption of innovative products and practices.
It’s important for medical device manufacturers to address two questions. First, are they offering a solution to a significant medical problem? Second, in an era when medical costs are threatening to escalate out of control, can they offer a significant value proposition?
At Invibio, we are confident we are offering innovation as we partner with medical device manufacturers to deliver implants that have the potential to offer improved outcomes and quality of life for patients. We are also confident that the potential to reduce post-operative complications will save costs for healthcare systems. It's this conviction that gives us the resilience to keep driving innovation into the market.
MPN: I understand there is also a prosthetic solution for use in dentistry, the JUVORA dental disc, made from Invibio's PEEK-OPTIMA, and that this is now under long-term study. What would you say is the likely future role of PEEK prosthetics in dentistry? Is this yet another example of PEEK's versatility?
JD: The JUVORA disc is CAD/CAM millable, so it can be used with all the advantages and efficiency of digital workflows. We expect computerised design techniques to have an increasing impact on PEEK-based implants and prosthetics, in dentistry, and quite possibly in other medical fields.
Dental clinician Bernd Siewert, at the Clinica Somosaguas, Madrid, has used the JUVORA disc extensively, evaluating patients long-term as his practice moved to fully digital workflows and a current third-generation of JUVORA-based prosthetics, reducing manufacturing time while delivering all the benefits of implantable PEEK.
Very positive findings at the Clinica Somosaguas, obtained from 21 patients with full-arch implant-supported screw-retained bridges on a PEEK framework, certainly indicate that PEEK has a potentially major role to play in the field of dental prosthetics due to its excellent biocompatibility and the many advantages of being metal-free. In this particular study there was no corrosion, and healthy soft tissue was maintained.12
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Supporting information available upon request from Invibio Biomaterial Solutions for all claims.