Company insight
New PEEK biomaterial for ingrowing implants
An additive makes the difference: Evonik modifies its proven PEEK polymer with osteoconductive properties. The innovative biomaterial can also be injection moulded, as Evonik is demonstrating with its partner Samaplast in initial prototypes. VESTAKEEP Fusion opens up new possibilities for modern implant medicine.
mplants made of the high-performance polymer polyether ether ketone (PEEK) have long been recognised as an equivalent alternative to metals, such as stainless steel, cobalt-chrome and titanium in many areas of application. However, these metals have so far been superior in terms of cell adhesion. Evonik, as an innovation driver, has recognised the need for ingrowth polymer-based implants. The manufacturer of high-performance polymers for medical technology has launched a new, osteoconductive PEEK biomaterial under the brand name VESTAKEEP Fusion, which improves fusion between bone and implants.
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Metal-free alternative for implants with permanent body contact VESTAKEEP is a proven biocompatible and biostable high-performance material for implants. Like all conventional PEEK plastics, it is inert and ignored by bone cells. This is an advantage in many cases, especially when an implant is not intended to ingrow, such as heart valves and stents, ports or pumps. In other applications, on the other hand, a stable bond to the bone is desirable, for example, in the case of spinal disc replacement bodies (cages) that remain permanently in the body.
“Implant manufacturers were missing a PEEK material that fuse with bone cells and thus accelerates healing, for example, after spinal surgery,” explains Marc Knebel, head of the medical systems market segment at Evonik. The speciality chemicals company is filling this gap in the market with VESTAKEEP Fusion. This provides an alternative to titanium, stainless steel or cobalt-chromium implants.
Functional additive: Biphasic calcium phosphate accelerates healing The experts from Evonik have succeeded in giving PEEK osteoconductive
112 Cage prototype from injection moulding demonstrates design diversity.
properties with the help of an additive, for example, modifying the compound so that bone cells adhere to the implant. The functional speciality additive is biphasic calcium phosphate (BCP). Calcium phosphates are a natural component of bone. If osteoblasts find body-like substances at the implant, they can dock there more easily. This positively influences osteointegration, the interfacial fusion between bone and implant. “This accelerates healing and thus convalescence and the patient’s quality of life,” Knebel emphasises. The development team at Evonik explored more than 50 different formulations to match the morphology and size of the particles to achieve optimal mechanical properties. The new compound was specially designed so that the functional additives are available on the surface of the injection moulded part.
Over 30% higher cell proliferation The first new development from the VESTAKEEP Fusion product line, the compound VESTAKEEP iC4800, has
excellent biocompatibility like all other VESTAKEEP i-grades for permanent implants. In addition, it facilitates the formation of new bone substance. This has been confirmed by common test methods. In vitro studies document over 30% increased cell attachment and cell proliferation. In preclinical tests, histological examination reveals a dense network of newly formed osteoblasts at the bone- implant interface. Bone histomorphometry shows an approximately twofold increase in bone apposition. And pull-out tests demonstrate a more than twofold increase in implant fixation.
Like all other high-performance polymers based on PEEK for medical technology, VESTAKEEP Fusion does not form any disturbing artefacts in imaging procedures such as X-ray or MRI – an advantage over implants made of metals. Similarly, for progress monitoring, it is necessary for the implant to be clearly visible on X-ray images. The BCP additive creates a natural shadow that allows the practitioners to accurately locate the implant and observe the fusion process.
Medical Device Developments /
www.nsmedicaldevices.com
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