Evonik and Samaplast AG are developing an osteoconductive PEEK biomaterial that can be injection molded. Previously it had been nearly impossible to manufacture implants from polymer compounds with bioactive particles by injection molding, because a thin polymer layer usually forms on the surface that overlays the particles, preventing the implant from growing in, the companies reported in a news release. VESTAKEEP Fusion's specially configured microparticles and their homogeneous distribution, however, makes functional BCP additives (biphasic calcium phosphate) available on the surface of injection-molded components.
"Implant manufacturers were missing a PEEK material that fuses with bone cells and thus accelerates healing, for example after spinal surgery," stated Marc Knebel, head of the medical systems market segment at Evonik, in a news release. "We are closing this gap in the market with VESTAKEEP Fusion and offering an alternative to titanium, stainless steel, or cobalt-chromium implants right away."
Added Samaplast CEO Stefan Okle: "We tested VESTAKEEP Fusion on injection molding machines in the clean room and found that it was very easy to process. Thanks to the excellent exchange with Evonik, we were able to produce a prototype within ten days." Previously, tool development alone had taken eight to ten weeks. With rapid prototyping, this process can be shortened considerably, it was reported.
Evonik and Samaplast's first prototypes are intervertebral implants, known as cages or spacers, which are used to fill the disc space in the spine following its removal due to disc degeneration. "We have produced a cage that contains all the details, such as serrations, threads, and apertures, that are relevant for spinal implants," stated Okle. The cage models show the design diversity in the interlocks and in the cavities for ossification. In addition, the design facilitates instrument guidance during surgery and also enables minimally invasive, patient-friendly surgical techniques.
Evonik's polymer experts are also developing a 3D-printable VESTAKEEP Fusion filament that could be processed in additive manufacturing using fused filament fabrication (FFF) technology. The material can also be milled, compression molded, and extruded.