It has been well over a decade since we first started to see metallic AM processes being used to make medical implants. Initially, these were bespoke implants made by companies such as Xilloc. But more recently we have seen companies such as Stryker, DuPuy, and Zimmer using AM for high volume device production. From hips and knee joints to cranial plates and spinal fusion cages, all made using medical-grade titanium by laser and electron beam melting.
In more recent years, we have also seen the advent of some medical-grade PEKK materials that can be processed using laser sintering. But beyond that, there is little in the way of ‘truly’ implantable 3D printing polymers, which is a shame as there are so many market opportunities emerging for such materials. That situation may however be about to change because new 3D printable polymers are being developed that can not only be implanted, but they can also be ‘tuned’ in several ways. The mechanical properties can be tuned to simulate different types of tissue. They can also be tuned to degrade over time within the body, slowly being absorbed and replaced by healthy new cells.
Many AM machine vendors and materials companies will claim to have a ‘medical-grade material’ that will be ‘biocompatible’ and tested to ISO-10993. However, on closer inspection, you will find that these materials can only be used in applications with a limited exposure period to human cells. In other words, there are suitable for functional prototypes, but little else.
Of course, there are 3D Printing systems, such as FDM, which can process biodegradable and bioresorbable materials such as PLA and PLGA. However, these processes fail to achieve the resolution needed for microscale implant manufacture, which is where these materials are typically used. That is because the human body finds it challenging to resorb large amounts of PLA or PLGA without localized swelling and rejection.
So, is there a more viable 3D Printing solution, suited to both small scale micro-device manufacture and larger scale reconstructive implants and scaffolds? Moreover, is there a commercially available material that can be tuned to have a specific rate of degradation in the human body, along with tunable mechanical properties?
Well, I think there might be!
In a bizarre coincidence, in a world of 7.8-billion people, I happen to live in the same small market town as the CEO of newly created 4D Biomaterials. 4D Biomaterials was spun out from the Universities of Birmingham and Warwick here in the UK back in April 2020. The company’s mission is to commercialize a new class of photocurable resins based on polycarbonate chemistry. The resins, developed by the company’s founders Professor Andrew Dove and Dr. Andrew Weems, are novel bioresorbable materials with good shape memory, tuneable mechanical and chemical properties, and promising tissue-healing performance.
Over the last 15-years, I have been asked numerous times by clients if I could identify biocompatible materials with these properties, and until now, I have struggled to find an answer. Now I think I have one. What is more, I am going to get a little closer to the action on this one, as Phil Smith CEO of 4D Biomaterials, has asked me to become the company’s 3D Printing advisor. It was not a difficult decision to make saying yes.
Images courtesy of 4D Biomaterials