Rebuilding Broken Bodies with 3D Printers
By Don Willmott
The Six Million Dollar Man may soon be available at a deep discount. Highly specialized and biologically savvy 3D printers are finding their way into hospitals, research labs, and medical schools, where they will undoubtedly upend healthcare in ways we can’t fully imagine yet. Sure, it’s easy to picture a 3D printer creating a replacement finger bone, but might it really be possible to “print” soft tissues, organs, and blood vessels for transplantation, improving surgical results while cutting costs at the same time?
Jawbones, hip joints, windpipe replacements, shoulder joints, even large skull sections and a face… the list of body parts that 3D printing has tackled continues to grow as the hardware, printing materials, and design software all steadily improve and come down in cost.
In fact, 3D printing is already playing an important role even before patients are wheeled into the operating room. At Boston Children’s Hospital, doctors routinely use 3D printers guided by pinpoint measurements gleaned from CT scans to create realistic models of patients’ body parts in order to perform “practice” surgeries. The printers they use build the models layer by layer with a resolution of between 16 and 32 microns per layer, about the width of a cotton thread. Using several kinds of resins, doctors can create colorful and detailed models of varying tissue types that are used not only by surgeons, but also as a tool to explain to anxious parents what’s going on to happen to their child. The end result: faster and more accurate surgery.
Orthopedics is a natural fit for 3D printing advances, and some of the 600,000 people who have knee replacements in the U.S. annually can benefit from getting their own knees scanned and then 3D-printed in wax. That mold is used to create a custom titanium replacement knee joint far more beneficial than an “off-the-shelf” replacement that would require more tissue and bone removal—and therefore more pain and a longer recovery cycle. While the procedure may cost more up front, insurance companies and Medicare seem poised to embrace it because of the lower cost of post-surgery therapy. Lower cost? It’s that kind of result that’s propelling 3D printing ahead at such a rapid pace.
Even the most delicate orthopedic surgery is being aided by 3D printing. In August, surgeons in Beijing were able to implant a 3D-printed second vertebra made out of titanium in a 12-year-old patient suffering from bone cancer. It’s the first time such procedure has been done, according to media reports.
What’s proving more challenging is the concept of 3D “bio-printing” of soft tissues. In June, researchers from the University of Sydney, Harvard, Stanford, and MIT printed the kinds of vascular networks that are necessary for growing large complex tissues and organs, a big step toward even more mind-boggling 3D bio-printing. The scientists were able to build a system of interconnected fibers that would serve as a sort of mold for artificial blood vessels. That structure was covered with a protein-based material and solidified by the application of light. When they removed the artificial structure, tiny channels coated with human endothelial cells were left behind. Amazingly, they grew into functioning capillaries in less than a week. The entire process was much faster and, at least in theory, far less expensive than other artificial methods of building blood vessels that have been attempted in the past.
One key to the ultimate success of 3D printing in the healthcare arena is the continuing development of so-called “biocompatible” materials that human bodies will readily accept and adapt to without post-surgery complications. For example, 3D parts are sometimes printed from the redundantly named polyetherketoneketone (PEKK), a semi-crystalline thermoplastic that has proved to work well for bone replacement. Connecticut’s Oxford Performance Materials recently won FDA approval for the use of PEKK in patient-specific 3D-printed cranial implants that can be used in facial reconstruction procedures.
The bottom line seems to be that no matter which body part is broken, diseased, or missing, engineering and medicine may soon be able to join forces to produce a spare with a comfortable custom fit. Last year, mechanical engineers at Princeton 3D printed their version of a bionic ear—so now even The Bionic Woman knows where to go for an upgrade.
Don Willmott is a New York-based journalist who writes about technology, travel, and the environment for a wide variety of publications and websites.