3-D printers in the operating room
Kim, an 18-year-old high school student, got into a car accident three years ago. He required a brain surgery that involved removing a part of his skull and augmenting it later. However, his body rejected the augmentation and the skull started to weaken, resulting in one side of his head being hollow.
In March, Yonsei Medical School pediatric neurosurgery Professor Shim Kyu-won created an artificial skull implant with a 3-D printer. The circular implant was made of titanium and 17 centimeters in diameter. Shim removed the bone cement and replaced it with the metal-based artificial bone.
“If the damaged part of skull is too large, existing surgical methods of reconstructing it with bone cement implant may be difficult to execute,” Shim said. “The metal skull implant printed out with a 3-D printer shortens the entire medical procedure and significantly reduces the risk of infection and complications.”
Doctors nowadays design shapes of internal organs using 3-D software programs and print them out.
According to U.S.-based Transparency Market Research, the medical 3-D printing market is expected to grow to $965.5 million by 2019, from $354.5 million in 2012.
Before the 3-D printer started being mobilized for bone implants, there were only two ways to fill the gap between bones. One way is to slice off a thin layer of skull on the undamaged side and the other way is to manually shape up a piece of plastic paste called polymethyl methacrylate (PMMA). Compared to the traditional manual way, 3-D printing is quicker and more sophisticated.
To print out a piece of human organ with a 3-D printer, doctors first take computer tomography (CT) on the body part and analyze it to design the blueprint using computer-aided design (CAD) software. Data is inserted into the program, which is connected to the 3-D printer, and the printer builds up the implant by spraying out titanium particles. Meanwhile, it trims the shape to make it more fitted to the skull gap by melting edges of the titanium with laser beams.
“3-D printers spray out particles in the air, so it allows doctors to skip the molding process,” said Lim Kwun-mook, a researcher at Medyssey, a local surgical instruments developer, “which saves significant time and expense.”
“It only takes a day to complete designing a titanium skull, and about three to 12 hours to print out it of the machine,” Lim added.
In the early days, surgeons and cosmetic surgeons were the first people who use 3-D printing technology in medical procedures. They usually used the printer when planning a surgery, training junior surgeons and manufacturing prostheses. Nowadays, the printer is also used to create artificial bones and cartilages.
“The 3-D printing technology is involved in the surgery procedure from very beginning, when we plan out the surgery,” said Baek Chung-hwan, head and neck surgeon at Samsung Medical Center. “We next print out the prostheses structures, implant them and then grow live cells on them so that artificial organs can operate like real organs.
“However, so far, no cases have succeeded in the last phase of surgery [growing live cells around the artificial implant],” Baek added.
Baek last year succeeded in nose implant surgery on a paranasal sinus cancer patient using the 3-D printing technology.
“The 3-D printing surgery can minimize side effects, as the doctor fully understands the patient’s face structure by simulating surgery via the 3-D printer program,” he said.
Following Baek’s nose success, a plastic surgeon successfully reconstructed a young man’s cheek.
Heo, an 18-year-old high school student, had almost half of his cheekbone removed as a child because of a tumor. Even though the tumor was successfully removed, Heo’s right cheek never recovered. As a result, he came to have a highly asymmetric face with his left eye higher than the right eye.
In September, Heo received a cheek implant with a small piece of customized artificial bone, about 4 centimeters wide and 2 centimeters high.
A month later, his eyes are level and his facial shape normal.
“In the past, we had to implant parts of the patient’s rib, which took seven to eight hours,” said Rhie Jong-won, a plastic and reconstructive surgeon at Seoul Saint Mary’s Hospital. “But now with 3-D printed artificial bones, surgeries only take two hours at most.”
“As the 3-D printing technology has advanced so it can restore a patient’s facial shape, the technology surely can come up with pieces of prostheses perfectly tailored to each patient,” said Cho Dong-woo, a bioengineering professor at Pohang University of Science and Technology (Postech) who constructed the artificial face bones for Heo.
Overseas medical societies are also working actively on developing surgical technologies in a bid to integrate 3-D printers in their medical practices.
The Peking University orthopedics department succeeded in printing out a set of titanium-based backbone pieces and implanting them in a 12-year-old bone cancer patient.
The medical circle predicts that 3-D printing medical technologies will further grow to be able to print out not just bones, but also complex organs like the lung and liver.
A joint research team between Harvard University and the University of Sydney, recently succeeded in printing out capillary vessels.
However, the technology will take some time until it can be commercialized after obtaining permits from the Ministry of Food and Drug Safety, as the cheekbone implant surgery also took time to receiving governmental approval.
“Under Korean medical safety law, we have to obtain permission for each surgery case, because these artificial implants are sized differently customized to each patient,” said Dr. Rhie from Seoul Saint Mary’s Hospital. “To accelerate technological development, the government should shorten the licensing procedures.”
BY PARK HYUN-YOUNG, KIM HYE-MI [firstname.lastname@example.org]
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It's a wrap