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WhitePaper: Bioplastics for 3D Printed Medical Implants

Polymers are particularly attractive in the medical device field due to their biocompatibility, mechanical properties comparable to those of the host tissues, and customizable manufacturing processes. Many synthetic polymers have been in clinical use for decades, both non-degradable (such as polypropylene, polytetrafluoroethylene, polymethylmethacrylate, or polyetheretherketone) and degradable (such as polycaprolactone, polyglycolic acid, or polylactic acid).

The 3D printing technology plays an increasingly important role in implantable medical devices due to its ability to print structures with complex geometries, thereby mimicking intricate designs found in nature and offering the possibility to create personalized geometries.

The use of polymers has advantages over metal printing approaches, which often result in metal implants that do not degrade in the body and may lead to mechanical issues such as stress shielding. 

In this whitepaper we present a database of bioplastics that can be used for 3D printing in the orthopaedic field, including manufacturing techniques, and mechanical and biocompatibility properties for the most commonly used polymers.

3D Printing Techniques

Several printing techniques are available for printing bioplastics:

  • Direct 3D printing/Inkjet
  • Selective Laser Sintering (SLS)
  • Stereolitography (SLA)
  • Low-temperature Deposition Manufacturing (LDM)
  • Fused Deposition Modeling (FDM)

Each technique uses specific materials, and has its own advantages and limitations. The wide choice of printing techniques provides versatility for material selection and supports designs with diverse structures and features.

Non-degradable and degradable plastic biomaterials in orthopaedics

In this whitepaper we present relevant mechanical properties (e.g., Young’s modulus, compressive and tensile strength) of the most commonly used non-degradable (polytetrafluoroethylene, polymethylmethacrylate, and polyetheretherketone) and degradable (polylactic acid and polycaprolactone) polymer materials in a clinical setting. We also discuss their biocompatibility and provide examples of current applications.

Towards customized, living bioplastics

Currently, there is a limited number of biodegradable polymers available for 3D printing. Therefore, there is a major need for research to fabricate novel biopolymers with tunable properties that can restore functionality at the site of application. 

However, design strategies such as architected, responsive, or functionally graded polymers, multi-material combinations, or material customization provide versatility and the possibility to manufacture 3D-printed parts with specific desired characteristics. Particularly with the recent developments in the field of mechanoresponsive materials, an implant material could become a living tissue with strong similarity to the original organ.

This whitepaper is part of a series on biomaterials suitable for additive manufacturing processes. Part 1 of this series, on metallic bio-materials was published before and can be found on our NEWS page.