A few years ago, there were only plastics, which could be printed into custom prosthetics and manipulated into patient-specific surgical tools. Then, titanium powder was loaded into 3-D printers to produce custom implants. Now mixed materials are opening up new possibilities.
The Feinstein Institute for Medical Research on Long Island is experimenting with something MakerBot calls limestone. The material is actually a composite of organic plastic and calcium carbonate that together mimics bone. More flexible materials that can act as other body parts are also in the works.
To gain FDA approval, any 3-D-printed material or device that comes into contact with patients must be capable of being sterilized. It can be a challenging process.
“Some materials go through something in the 3-D printing process that makes them nonsterile,” said Weimer of 3D Systems. But she said FDA approval for 3-D printed products is becoming more common.
Some New York hospitals are hoping to speed up the pace of adoption — and plant the seed for more homegrown innovation — by creating in-house 3-D printing centers where experienced users can assist novices.
Within hospitals, 3-D printing capabilities can vary widely by department. Two medical units at NYU Langone have their own printers, while Levine and his team collaborate with 3D Systems, using the company's printers and software. Other departments don't use the technology at all.
Dr. Oren Tepper, director of craniofacial surgery at Montefiore Medical Center in the Bronx, has been using the technology since 2007 and, like Levine, outsources his printing needs to 3D Systems. Now, however, he is in talks with Montefiore about creating a 3-D printing center on-site that would be widely accessible to physicians at the hospital.
“I think the main limitation of 3-D printing is not functionality or cost but awareness of what can be done,” Tepper said. “The majority of health care workers don't even have the knowledge that this technology exists.”
Stern herself was only vaguely aware of 3-D printing before her diagnosis in March 2014 of a benign but fast-growing tumor called an ameloblastoma. While researching second opinions, she found Levine and his team of surgeons at NYU Langone and was soon buoyed by the doctors' confidence and the “after” pictures they showed her of previous patients.
Stern's jaw-in-a-day surgery began early one May morning in 2014. Her parents and sister bided their time in the waiting room as the surgical team removed her jaw and cut the bone from her leg.
Careful digital planning and the 3-D-printed cutting guides FedExed to them by 3D Systems allowed her doctors to work simultaneously, knowing that everything would match up in the end. The implant carved from her leg fit her jaw perfectly. The same was true of the titanium plate the surgeons had designed to hold Stern's new jaw in place.
Before 3-D printing entered the equation, there was a lot more “eyeballing,” according to Levine. He couldn't go into the operating room with a metal plate the exact size and shape he needed. Instead, he had to manipulate the standard pieces of metal he had on hand while the patient was sedated.
“As you can imagine, sitting in the O.R. with a set of pliers to make [the plate] fit the jaw is somewhat time-consuming,” said Dr. Daniel Ceradini, associate director of microsurgery at NYU Langone, who also helped develop the jaw-in-a-day procedure. If the placement of the plate or jaw implant were just a few millimeters off, the patient could suffer.
Into the jaw implant, the surgeons inserted the screws that would secure Stern's new dentures. For this, they used a drilling guide, which is really just a few centimeters of plastic that aids in the placement of a screw hole. Still, it's a piece of plastic that Levine and Ceradini insist makes all the difference by eliminating guesswork that could lead to costly complications.
When Stern left the operating room after 12 hours, disoriented because it was dark outside, her sister turned pale. “Is that Zeesy?” she asked her father. Stern's face was severely swollen. She had to spend a week in the hospital, being fed through a tube in her throat. Afterward, Stern spent two months at her parents' house, embarrassed to go outside because she had yet to receive her dentures.
Three months post-op, though, she was back at work. Despite the chunk of bone missing from her leg, she was running after the kids she teaches at a preschool near Central Park.
“It's always going to be a little stiff,” said Stern, touching her jawline. She has a faint scar on her throat where her feeding tube had been inserted, and a slight indentation to the left of her chin — both of which she has to point out to people for them to notice.
Since her surgery, Stern's doctors have continued to refine their methods. They are now able to fit a patient's dentures on the day of surgery. Soon, Ceradini said, the dentures will be 3-D-printed as well.
Within a decade, Levine predicts, 3-D printers will be as common as CAT scans, which, in 1995, were just as novel as 3-D printers are now. His colleague Ceradini agrees. “Looking down the road 10 years, having a 3-D printer that's in the office or in the clinic will become the new mainstay,” he said, “as opposed to having one company that prints these things and FedExes them to you the next day.”