The challenges of medtech 3D printing

If you are at all curious about how 3D printing is shaking up the medical space, you should make a point of attending the MD&M West exhibition and conference in Anaheim, CA, next month. The largest medical manufacturing event in the nation, MD&M West will devote a full day to a discussion of 3D printing, exploring its use in everything from prototyping and the production of finished custom devices to bioprinting tissues and organs. The regulatory pathway in all its twists and turns also will be addressed. One of the high-profile speakers at the session, Scott Hollister, PhD, a professor of biomedical engineering at the University of Michigan, can be called a miracle worker. He made headlines a few months back when he and a colleague at the university, Dr. Glenn Green, designed and 3D printed a tracheal splint that saved the life of an 18 month old. PlasticsToday reported on the story in March 2014.

While 3D printing clearly has tremendous potential in advancing medical technology, it is not without its challenges. Hollister will address some of them during his presentation, "Material developments for 3D printing: From biocompatible polymers to metals," on Feb. 10.

Materials pose a number of challenges in 3D printing of medical devices, Hollister told PlasticsToday.

Particle size is a significant issue, says Hollister, "as this has a big effect on being able to laser sinter structures. For us, the mean particle size of the poly-epsilon-caprolactone (PCL) should be between 75 and 100 microns, or 0.075 and 0.1 millimeters." PCL has a history of use in long-term implantable devices because of its degradation rate, which is slower than that of polylactide.

Another obstacle, according to Hollister, is the availability of materials. "You need to be able to work with a broad range of materials to produce medical devices, from soft elastomers to very stiff materials," says Hollister. That is lacking in 3D printing.

As for the materials currently used in 3D printing applications, they also are subject to a range of limitations, ranging from heat resistance to strength. And then there's cost. "When you are using qualified materials that have been through the appropriate regulatory process, you're looking at spending upwards of $7 per gram," says Hollister.

As demand for medical-grade materials increases--and it will--supply will follow. The other hurdle for 3D-printed devices is regulatory approval. Hollister was a speaker at an FDA-sponsored workshop in October, 2014, and he came away with a favorable impression.

His interactions with FDA regarding the 3D-printed tracheal splint went well–FDA granted him and Greene emergency clearance to implant the device–and he is mindful of the agency's mission to balance safety and efficacy. And it does seem that FDA is making a real effort to facilitate the emergence of 3D printing in medical applications.

In an interview published earlier this month in PlasticsToday, Steven K. Pollack, PhD, Director of the Office of Science and Engineering Laboratories at FDA, recognized the potential of the technology while cautioning users that in some cases it may lack the controls of traditional medical manufacturing technologies. "Devices manufactured using 3D printing technology may need additional or different testing than what is normally performed for products that are manufactured using traditional (subtractive) techniques," Pollack told PlasticsToday.

"Design controls and validation are challenging issues when it comes to 3D printing," agrees Hollister. "This is a paradigm shift for the industry and its regulators. It can't fit neatly into the 510(k) process, where a predicate device and some benchtop testing will suffice to get clearance. A big question is: How much testing needs to be done for custom devices?"

You can begin to find answers to some of these questions at Enter the 3D Printing Era, a full-day session on Feb. 10 during the MD&M West exhibition and conference in Anaheim, CA. The three day exhibition and conference is co-located with PLASTEC West at the Anaheim Convention Center from Feb. 10 to 12.