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3D Printing Materials: A Missing Link. M. Scott Taylor, Poly-Med, explains why 3D printing has huge medtech potential.

Just the other day, as I was purchasing a new set of tyres, I was reminded of the importance of quality in materials. While new features and technological advancements are obvious on recent cars (few of which are present on my 15-year-old commuter), the only parts keeping 3,200 pounds of steel firmly to the road is the rubber I was about to buy. The decision to select a certain tire was not based entirely on price. This critical product met a variety of other specialty requirements including total lifetime value, safety profile, and manufacturer reputation. A closer look, and this checklist mirrors selection requirements we use for medical materials.

I recently attended a talk by Dr. Frank Rybicki (The Ottawa Hospital), a major proponent of 3D printing applications in medicine. Dr. Rybicki is calling 3D printing the next revolutionary advancement in medtech, akin to the introduction of CT and MRI. Just like CT and MRI, 3D printing provides the ability to create and study, peel away confounding layers, and simplify the complex. A low-hanging fruit for this technology, similar to other imaging formats, is to create patient-specific anatomical models for pre-surgical planning and customised surgical guides. These are powerful, life-saving tools that improve outcomes.

And what if we could do more?

The full benefit of 3D printing lies in our ability to see and plan better, and to also improve therapies through cutting edge devices. Quality and speed of additive manufacturing continues to advance, creating a new need for a variety of materials to support implant applications. Permanent polymers, such as PEEK, have been adapted for use in 3D printing, except that few implant-grade bioresorbable materials have been introduced.

An implanted device carries additional risks over a visualisation or practice aide and requires full functionality, performing the designed task as well as or better than alternative products. In this way, 3D printing needs to be competitive with traditional manufacturing operations like injection moulding, not just in terms of part performance but also with manufacturing considerations such as cycle times and process costs. Printer manufacturers are continually pushing the envelope by producing relatively inexpensive and faster printers that may be reasonably associated with a manufacturing process. Part performance though, relies just as much on the quality of material used to create the product.

An excellent opportunity for applying advanced design capabilities with 3D printing includes the class of bioresorbable products. Benefits of bioresorbable devices are conceptually straightforward. These devices can provide structure for healing tissues when needed, and degrade to leave the body in a natural, pre-injury state with no need for further intervention. This is particularly of interest in paediatrics, where the patient is growing and permanent implants can be restrictive, causing complications after they are no longer needed. There are several case studies of successful applications in paediatrics, proving the utility and potential of 3D printing implants.

Bioresorbable materials are relatively common in 3D printing – PLA is easily purchased from a variety of sources. These products likely do not meet the minimal requirements for medical-grade use as many are modified, containing additives to improve printing performance. To create a device that is intended for implantation, it is necessary to be more selective about the materials used to generate parts that are consistently both safe and effective.

A first step towards supporting 3D printing of bioresorbable implants is creating more available materials. Having access to PLA that meets USP Class VI requirements is a start, and a good fit for orthopaedic applications, though future availability of alternative materials with a variety of performance and degradation profiles will support development of more diverse indications.

As we start to adopt 3D printing as a viable option to manufacture implanted products, there are best practices that can be applied to assure materials have the best chance of consistently meeting expectations. The promise of a revolution in patient care using 3D printing is being realised. Equipment is more accessible than ever, and by using the best materials we can maximise this benefit. Because using the right materials is where the rubber meets the road.

5 Best Practices for selecting bioresorbable 3D printing materials

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