Commercial-scale production of medical implants meets the needs of large groups of patients suffering from specific diseases. The advent of additive manufacturing offers a route to the design of personalized devices for patients with rare conditions not addressed by conventional mass manufacturing. However, as researchers from the University Medical Center Utrecht in The Netherlands discovered, regulatory and logistical challenges can impede the timely adoption of new technology.

Two case studies outlined in The Lancet provide a blueprint for overcoming these hurdles in outfitting two (A) First step in the design process: a prototype that follows the mechanical axis near the spine, attaching to the last mechanically stable vertebrae in the cervical spine (C4–C5) and bridging the unstable part (C6–T11) to the first mechanically stable vertebra distal of the defect (T12). (B) Restructured prototype with addition of screw holes and their trajectories. (C) Final implant design (rendered picture). (D) Close-up view of the porous mesh structure to allow bone ingrowth, with distal screw holes. Source: K. Willemsenpatients with rare spinal conditions with custom-made 3D-printed metal implants. The research team ensured compliance with EU Medical Device Regulations with a procedural agenda and a technical file with a detailed description of all steps and procedures. This process involved the collaboration of surgeons and engineers with input from the department of medical technology, which has extensive knowledge of implant legislation and legal matters.

The implants were customized to treat a patient with neurofibromatosis and another with vanishing bone disease. The devices were designed based on patient CT scans and with the aid of CAD software, and were 3D-printed using titanium. Prototypes were evaluated in compression strength tests and cadavers.

The planning and workflow framework described could encourage physicians to treat patients — previously considered untreatable — with personalized techniques.