Additive Manufacturing: Advancing the Quality of Personalized Medicine
FDA Authors: Jennifer Y. Kelly, interdisciplinary scientist; Eric N. Horowitz, quality system lead; James C. Coburn, senior research engineer; and Matthew A. Di Prima, materials scientist
Additive manufacturing (AM), also known as 3D printing, has been used by the aerospace and automotive industries since the late 1990s. Until recently, it was the domain of large production operations, but now entrepreneurs have utilized the technology with food, toys, and gadgets. In addition, more members of the medical and healthcare community are adopting 3D printing to create truly personalized medicine.
AM printers fabricate objects by laying down successive layers of material using four main techniques: stereolithography, selective laser sintering, ink jet printing, and fused filament fabrication. AM techniques can fabricate single piece components of almost any shape—no matter how complex—from metal, polymers, or ceramics. This capability allows for flexible manufacturing on shorter timelines. Physicians and surgeons now can use AM to create anatomic models of patient organs for surgical planning, preparation, as well as educational tools. AM also is used to make patient-matched surgical guides. Over time, the accuracy of production and material choices have improved, allowing manufacturers and specialized research hospitals to use AM to create implantable devices.
Developing completely personalized medical products remains challenging, however, due in part to limitations in the precision of medical imaging data to produce accurate device blueprints. Final quality also depends on various factors associated with all phases of the process. Technical challenges remain, including, but not limited to, material deposition control and monitoring, porosity, biocompatibility, anisotropy, recyclability of materials, and cleaning of internal structures.
There are a range of medical devices approved or cleared by the U.S. Food and Drug Administration that are manufactured using AM, including: skull replacements, patient-matched implants, patient-matched surgical guides, orthopedic devices (hip cup, spinal cages, knee trays), and dental devices (temporary bridges, reconstructive). Bioresorbable tracheobronchial splints have also been implanted under Emergency Use Authorizations in patients younger than 2.1 The technology allows for new design freedoms and device personalization; however, it also poses new challenges for designers and regulators.
One potential challenge is the utilization of alternative manufacturing locations. Production soon may take place outside conventional factory settings, such as at bedside in a hospital or in other locations that lack the controls called for by the Quality System Regulation. The traditional roles of designer, manufacturer, and users may become blurred as groups develop novel products. AM equipment manufacturers and software developers also may play a larger role in the device development process.
The FDA is considering how current regulations best ensure reasonable safety and effectiveness of medical devices, while allowing for rapid innovation. Changes to the traditional device manufacturing paradigm may require a re-examination of which stakeholder (printer maker, software producer, final device manufacturer) assumes which regulatory responsibilities. The Center for Devices and Radiological Health realizes the potential and challenge of AM of medical devices and hosted a technical workshop this past October to discuss the critical aspects of fabricating medical devices using AM. Content of the technical workshop is being considered for draft guidance.