3-D printers making inroads in medical world

December 19, 2013

By RYOSUKE NONAKA/ Staff Writer

Last year, a 10-year-old boy in Aichi Prefecture had surgery to extend his jawbone and give it a natural shape. He went under the knife at Fujita Health University Hospital in Toyoake.

Prior to the procedure, Takayuki Okumoto, an associate professor of plastic surgery, briefed the boy and his parents. Okumoto explained where he would cut the bone as he showed them a model of the boy's skull--reproduced by a 3-D printer.

The use of 3-D printers is now coming into its own in medical settings.

In areas such as plastic surgery, the technology is helping to build three-dimensional models of patients' skulls, examine surgical methods and provide explanations to patients.

The range of applications for 3-D printers has also grown, exemplified by progress in the commercialization of artificial bone for implants.

The 10-year-old boy's mother said the 3-D model "made it easier to understand than if (the doctor had) just used a computer. We learned what they would do and it reassured us, so we could cope with the surgery."

The procedure went as planned and the boy's deformed bone was fixed. He is now a happy, cheerful student.

According to Okumoto, methods of creating a model of a patient's skull have been around since the 1980s.

Under the old technique of solidifying resin with ultraviolet and other light, "it cost upward of 100,000 yen ($970), and the texture was very much different from real bone."

Japan's government-run health insurance system began to cover the production of 3-D models in 2008, eliminating the financial hurdle most patients faced.

Fujita Health University Hospital worked with a Sony Group company and other partners to develop an approach for making models from a cheap material: salt. The 3-D models, made from salt (sodium chloride) shaped into special grains, feel more like real bone than conventional resin or plaster.

To build a 3-D model, about 100 CT images are made by scanning cross-sections of the patient's head, and a computer stacks together the images to create the 3-D data of the skull.

A printer then arranges the salt in hardened layers until producing a three-dimensional model identical to the patient's skull.

The hospital now makes 30 to 40 3-D models a year for patients who have crooked jaws or physical speech impediments, as well as to help treat hereditary diseases that lead to deformed jaws or ears such as Treacher Collins syndrome.

"If 3-D printers continue to become more widespread, then their use may expand to making models in treating conditions in acute stages, such as external injuries suffered in accidents," Okumoto said.

COMMERCIALIZING ARTIFICIAL BONES

Research is under way at the University of Tokyo to make artificial bones for implantation in real-life patients by using 3-D printers.

The researchers have already implanted artificial bones in the faces of around 30 patients during clinical trials, and these test subjects have been doing well since undergoing the procedures.

The university will soon apply to the health ministry for production approval, with hopes to commercialize the technique.

These artificial bones were developed by a team led by University of Tokyo professor of medical engineering Yuichi Tei and a health care start-up.

The material is a powder of calcium phosphate, the main component in real human bone, and is given shape by spraying water on it.

First, the researchers use a 3-D printer to make a preliminary model of the patient's skull, then fashion plaster into parts to fill in the damaged or missing portions.

These parts are then turned into bone-like replicas by spraying the calcium phosphate powder based on the 3-D data.

A typical facial bone implant involves removing bone from the lower back or elsewhere to be carved into the desired shape and embedded in the face.

However, this approach runs the risk of nerve injury or other dangers during the removal process.

Since 2009, Tei and his team have been implanting artificial bone into pieces of jaws lost to cancer surgery and accidents.

Upon inspecting the implants a few years later, he found that they have assimilated with the existing bone.

In addition to bone lost to accidents and other incidents after birth, the professor's artificial bone implants have also assimilated with the natural bone of patients born with small jawbones.

"A lot of people suffer from facial deformities, both hereditary and acquired," Tei said. "By making artificial bones more widespread, we can improve the quality of life without injuring the body."

By RYOSUKE NONAKA/ Staff Writer
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