Will 3-D Printing Revolutionize Medicine?
By Sonya Collins
Reviewed by Brunilda Nazario, MD
July 23, 2014 -- Sydney Kendall lost her right arm below the elbow in a boating accident when she was 6 years old. Now 13, Sydney has used several prosthetic arms. But none is as practical -- nor as cool, she'd argue -- as her pink, plastic, 3-D-printed robotic arm.
The arm was custom-designed for her this spring, in pink at her request, by engineering students at Washington University in St. Louis through a partnership with Shriners Hospital. They printed it while Sydney and her parents watched.
"It took about 7 minutes to do each finger," says Sydney's mother, Beth Kendall. "We were all blown away."
When Sydney wore her new arm to her school outside St. Louis, her classmates were blown away, too. "They were like, 'Sydney, you're so cool! You're going to be famous!'" Sydney recalls.
The robotic arm, with its opposable thumb, helps Sydney grip a baseball, maneuver a mouse, and pick up a paper coffee cup.
The cost? About $200. Traditional robotic limbs can run $50,000 to $70,000, and they need to be replaced as children grow.
"Kids don't usually get to have robotic arms because they are so expensive," Beth Kendall says.
Robotic arms like Sydney's are just one example of how 3-D printing is ushering in a new era in personalized medicine.
From prosthetics to teeth to heart valves, it's bringing made-to-order, custom solutions into operating rooms and doctors' offices. Experts say dozens of hospitals are experimenting with 3-D printers now, while researchers work on more futuristic applications of the technology: printing human tissue and organs. To foster even more research, the National Institutes of Health in June launched a 3-D Print Exchange that allows users to share and download files.
"3-D printing is a potential game-changer for medical research," said NIH Director Francis Collins, MD, PhD, in announcing the exchange. "At NIH, we have seen an incredible return on investment; pennies' worth of plastic have helped investigators address important scientific questions while saving time and money."
As one of the leading researchers in the field, Anthony Atala, MD, director of the Wake Forest Institute of Regenerative Medicine, understands its promise firsthand. The institute has already created miniature livers that live in petri dishes as a step toward creating organs. "3-D printing has the potential to revolutionize medicine," he says.
What Is 3-D Printing?
Imagine an ink jet printer that, rather than spraying out ink in the shape of letters, sprays out a plastic or metal gel or powder in the shape of a tooth, finger, or a hip joint. A typical printer receives a document to print, while 3-D printers take their commands from an MRI or a CT scan of a body part. Also known as "additive manufacturing," 3-D printing produces an object, layer by layer, from the ground up.
Although 3-D printers have been around since the 1980s, medical uses have skyrocketed in the past few years, experts say.
They can produce more complex shapes than traditional manufacturing. This allows the products to be highly personalized: a tooth that looks just like the one you lost, or an exact replica of a hip joint.
The process can save time and practically bring production of medical devices to the patient's bedside. Although no one has exact numbers, University of Michigan biomedical engineering professor Scott Hollister believes about several dozen medical centers in the country now use 3-D printers in some form.
Teeth, Limbs, and Hearing Aids
3-D printing is already widely used for body parts -- usually made of plastic or metal -- that come in contact with the body but don't enter the bloodstream. These include teeth, hearing aid shells, and prosthetic limbs.
"In the past, a dental crown had to be fabricated in a lab, which takes a few days if not a few weeks and two to three trips to the dentist by the patient," says Chuck Zhang, PhD, a professor of industrial and systems engineering at Georgia Institute of Technology. Now a dentist can take a 3-D scan of a tooth and print the crown on the spot.
The technique gives amputees like Sydney an alternative to ugly and ill-fitting prosthetics. 3-D printing studios often collaborate with clients to design stylized, artistic limbs the user wants to show off -- not hide.
Zhang and his colleagues at Georgia Tech are working with military veteran amputees to correct their prosthetics' notoriously poor fit. His team is using 3-D-printed materials to create a prosthetic socket that adapts to the body's changing fluid levels. It will tighten or loosen as needed so the limb doesn't fall off or become painfully uncomfortable.
3-D-printed plastics and metals have also made their way inside the body. Doctors at University of Michigan's Mott Children's Hospital have saved the lives of two babies since 2012 by implanting 3-D-printed plastic splints into their windpipes.
The babies had a rare birth defect called tracheobronchomalacia. Without treatment, their weak airways would collapse, suffocating them. The only treatment is to insert a tracheostomy tube and put the baby on a ventilator for up to several years until, hopefully, the airways become strong enough to stay open on their own.
But 17-month-old Garrett Peterson's airways weren't showing any signs of getting stronger while on the ventilator. Doctors in Utah, where the Petersons live, said they had done all they could.
"Everything had to be perfect in the world. Garrett couldn't cry, or he'd turn blue. He couldn't poop, or he'd turn blue," says his father, Jake Peterson. "We just had to hold him and keep him perfectly happy, so it wasn't realistic to keep him on the ventilator."
The Petersons had read an article about a similar baby helped at the university in 2012 with a 3-D-printed tracheal splint, and they sought the help of Mott surgeon Glenn Green, MD.
"We decided this was Garrett's only chance. The hospital here in Utah said to enjoy him for the rest of the time we had him. And we weren't ready to do that," says Natalie Peterson, Garrett's mother.
Based on CT scans of Garrett's airways, Green and biomedical engineering professor Hollister designed and printed custom-fit splints to hold Garrett's airways open. His body will eventually absorb the device, and the airways will stay open on their own. Mott Children's Hospital says it was the first facility in the world to perform this procedure.
"I think it was the first example of using a 3-D-printed device in a life-or-death situation," says Hollister, referring to the baby helped in 2012.
Costs for a tracheostomy and extended time on a ventilator exceed $1 million per patient. The splint totaled $200,000 to $300,000, says Hollister.
Surgeons have implanted other 3-D-printed devices into patients. Cranial plugs fill holes made in the skull for brain surgery. Cranial plates can replace large sections of the skull lost to head trauma or cancer. Mayo Clinic and some other hospitals offer 3-D-printed hip and knee replacements to eligible patients. The custom joints minimize surgery and recovery time, as surgeons do not have to chisel away at bone to put them in.
The FDA has two labs that are investigating how the technology may affect medical devices.
In addition to metals and plastics, doctors and scientists around the country are loading 3-D printers with human cells and printing living tissue, called bioprinting. The Holy Grail is to print a living organ for transplant using a patient's own cells. Some experts predict this could be just a couple of decades away and potentially revolutionize organ transplants. Patients wouldn't die waiting for organs, and their immune systems wouldn't reject the organs.
Atala of the Wake Forest Institute says researchers will use the miniature livers they created to test drug toxicity. They expect the method to be far more accurate than traditional animal and cell testing, he says.
Biomedical engineers use several methods to print an organ. The printer creates a plastic mold of the organ that can be covered with the human cells. Or the printer can jet the cells out inside a collagen-based gel that will hold it all together. The cells must grow on the plastic or collagen scaffold for several weeks before the organ could potentially work. After putting it into the body, the scaffold disintegrates, leaving only human tissue behind. For children, this would mean the tissues could grow with them, eliminating the need for surgeries as they grow.
Already, bioengineers at Cornell University have printed ears, and the University of Michigan is also testing the concept. Many labs already print tissue for research and drug testing, and patching damaged organs with strips of human tissue may happen in the near future, says Stuart Williams, PhD, of the Cardiovascular Innovation Institute at the University of Louisville.
The first printed windpipe may not be too far off either, says Faiz Bhora, MD, co-director of Mount Sinai Hospital's Airway Center. Bhora and his colleagues are building windpipes both with plastic and gel bases in hopes of helping patients born with defects or tumors that block their airways.
As centers like Bhora's work on future applications, Hollister predicts the immediate benefits of 3-D printing will lead to having one in every hospital.
Williams offers a prediction, too: "3-D printing will change the delivery of health care."
SOURCES: Chuck Zhang, PhD, professor, industrial and systems engineering, Georgia Institute of Technology. Scott Hollister, PhD, professor, biomedical engineering, University of Michigan. Anthony Atala, MD, director, Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine. Stuart Williams, PhD, chief, Bioficial Heart Division, Cardiovascular Innovation Institute, University of Louisville. Faiz Bhora, MD, co-director, Airway Center of New York, Mount Sinai Health System.The Kendall Family. The Peterson Family. National Institutes of Health: "NIH launches 3-D print exchange for researchers, students." FDAVoice: "FDA Goes 3-D."