Using a printer to produce lifesaving medical implants and body parts might sound like science fiction, but it is already a reality in China. Peking University Third Hospital, a top hospital in China, recently announced that its Orthopedics Department has been using enhanced implants produced by a 3-D printer in a clinical trial, with promising results.
"We started clinical trials on 3-D produced implants late last year, and now we have used dozens of such implants in more than 50 patients," said Liu Zhongjun, director of the department. "All the patients recover very well. Nobody seems to have any undesirable side effects or adverse reaction."
The process of 3-D printing, or additive printing, applies successive layers of material in different shapes to make a three-dimensional solid object from a digital model. For the implants, the material used is titanium, a special metal that has been used for orthopedic implants for decades. However, the shapes of the 3-D products are much different than earlier models. Orthopedic implants are artificial devices incorporated into joints and bones to restore normal functions, such as spine implants to help anchor the spine, or hip replacements. They are widely used for patients suffering from bone damage caused by injury or disease, such as osteoarthritis, which causes pain and stiffness in joints.
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. 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.