Custom-made implants: osteoconductive filament for 3D printed implants

Evonik recently expanded its product line to include VESTAKEEP® iC4800 3DF, a new osteoconductive PEEK filament that improves fusion between bone and implants. COMPAMED-tradefair.com wanted to know what makes this new filament so unique and asked Marc Knebel, Head of the Medical Systems Market Segment at Evonik.

Mr. Knebel, Evonik has developed a new filament for 3D printing that promotes fusion between bone and implant. First things first, what makes your new product stand out from other filaments?

Mark Knebel: The new material is a special compound, a particular formulation which includes an additive that improves adhesive performance.  The functional specialty additive is biphasic calcium phosphate or BCP.

Does that mean adhesion is not improved via a coating but is rather the result of a material attribute?

Knebel: That’s right. We are talking about particles that are added to the material. We pay special attention to the size and morphology of the additive to ensure the mechanical properties of the filament are not altered too much.

So, this is not a new type of additive?

Knebel: No, BCP is a widely used additive and considered the gold standard in this area by most implant manufacturers.

How do you process or print the filament?

Knebel: We use granules to fabricate the filament. The latter is wound on spools and fed into the printer via the spools at the production site of the medical device manufacturer. Subsequently, it is being fused and printed layer by layer via the printhead and nozzle to achieve the desired shape.

Does this mean you create the accurate fit on the computer and then just print it?

Knebel: That’s right. Due to high melting temperatures, PEEK-based printing is more intricate than printing with other materials. However, the technology is similar to "conventional" filament printing. Still, the processing conditions differ because of the high melting point of about 400 C.

What types of implants can be created with the new filament? Are there any restrictions?

Knebel: A medical device is always subject to multiple factors, which include both the material and the design. Essentially, there is nothing we must explicitly eliminate in this setting. It can be evaluated whenever you want implant adhesion. It all depends on the requirements a material must meet. You must always check on a case-by-case basis whether it is consistent with the material properties, the printing process, and the design.

Does this type of filament provide more advantages than the types you have fabricated in the past and are there already any studies on the subject?

Knebel: We have conducted research that confirms improved adhesion. This is shown by the pullout strength of pins which proves two-fold and an in-vitro study documenting an over 30 percent increased cell attachment.

What feedback have you received pertaining to the new filament?

Knebel: We have presented it to a select group of innovators and received positive feedback. These companies have also conducted their own research and confirmed that the additive indeed affects the surface and improves fusion.

Are you planning on attending COMPAMED 2022?

Knebel: Yes, we will be an exhibitor at COMPAMED.