Due to the limits of traditional engineering methods, the shapes of orthopedic implants used nowadays are usually geometric patterns and, as a result, cannot attach to bones firmly without additional cement, screws or fixing plates.

But 3-D printing can virtually produce implants in any shape, as long as the computer that controls the printer has a digital model to follow.

A 3-D printed medical implant is shown at Peking University Third Hospital in Beijing, Aug 6, 2013. Dozens of such implants have been used in more than 50 patients, said Liu Zhongjun, director of the Orthopedic Department of the hospital. [Photo by Zhu Xingxin/Asianewsphoto]

Thus, such implants match better with the bones around them than traditional ones.

Also, through tiny pores Liu's team deliberately made in the new implants, bones are able to grow into the implants, securing the implant.

In this aspect, 3-D printed implants are more reliable than traditional ones,” Liu said.

"Although the probability is very low, yet it is possible that under long-term pressure from inside the body, traditional implants might plug into bones gradually, or become detached from bones. But there will be no such problems for 3-D printed implants."

Such improvements take time.

Liu's team started its program in 2009, with a medical device company that owns an imported 3-D printer.

The medical team provided designs based on their clinical experience and understanding of surgical needs, and the company digitalized the design for printing.

In mid-2010, they finally produced the implants they wanted and started animal trials on sheep.

When the animal trials proved the implants were safe and useful, the team applied to health authorities for permission for human trials.

In late 2012, they launched clinical trials.

Liu said 3-D printing has been applied a lot for aeronautics and astronautics, but more needs to be done in the medical field.

Zhang Weiping, the technology director with the medical device company, agreed.

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