by Hannah Whiteoak
3-D printing is the process of manufacturing objects by building them up layer by layer. As this new technology develops, it is finding an ever-greater range of applications in a variety of fields. One area where 3-D printing could truly change lives is in the manufacturing of medical implants.
From artificial bone and joint replacements to prosthetic body parts and life-saving pacemakers, medical implants restore quality of life to people who have been affected by injury or illness. Researchers all over the world are working on developing new implants that are produced using 3-D printing. This highly-flexible manufacturing technique could massively improve the range and quality of implants that are available.
3-D printing uses a metal, polymer or silicone powder as its starting material. This material is then melted and applied in layers to form a precise shape.
Commonly-used materials in the manufacture of 3-D-printed implants are titanium, which is used to create artificial bones and support structures, and medical-grade silicone. However, researchers are working on ways to use 3-D printing to create implants made of organic materials that closely resemble the patient’s own cells.
- The shape of each implant can be precisely customized to fit the patient’s body.
- Implants can be made from polymers that are similar to the natural tissues that they are replacing.
- In some cases, implants can be made much more quickly using 3-D printing.
3-D printing is already being used in many medical institutions to create customized implants for patients. Here are some current medical applications, as well as applications that we can expect to see in the near future.
Artificial bone replacements have been around for decades, but now 3-D printing techniques are making it possible to create implants that are highly customized to fit the patient’s body exactly.
A patient in the United Kingdom with a rare bone cancer recently received a custom-made, 3-D-printed implant to replace half of his pelvis, which had to be removed due to cancer. Doctors decided not to rely on standard bone replacement implants because there was not enough bone left behind in this case to attach the implants properly.
Instead, they scanned the man’s pelvis prior to its removal and used this scan as the blueprint for the new prosthetic. The implant was printed from titanium powder and coated with a biocompatible coating that encouraged integration with the remaining part of the original pelvis.
Other researchers are working on printing actual bone. These bioidentical orthopedic implants are made from the patient’s own cells, meaning that they function exactly like original bone.
The 3-D printer is used to create a polymer scaffold in the precise shape of the bone that needs to be created. This scaffold is then coated with stem cells taken from the patient, which over time develop into bone cells. The scaffold eventually degrades, leaving the bone in place. The result is that the bone is fully integrated into the patient’s body.
Dentists commonly use implants to replace teeth that have been lost due to decay or knocked out in an accident. Dental implants can sometimes be formed from acrylic resin and screwed into the jawbone using titanium pins, but some patients do not have enough healthy jawbone tissue to make this process possible. These patients need to have artificial titanium structures implanted in their lower jaw to support the bone there before artificial teeth can be fitted.
In 2012, an 83 year-old woman became the first person to receive a 3-D-printed titanium jawbone, after her own jawbone was almost completely destroyed by a bone infection. The new jawbone had an intricate structure that helped it to integrate with the surrounding muscle and nerves. Once the design had been created on the computer, the jawbone took just hours to print.
Demand for organs is currently running high above supply, with many patients dying while waiting for a transplant. Therefore, the possibility of being able to create artificial organs that perform as well as their natural counterparts is exciting for doctors and medical researchers.
In 2013, scientists at Organova in San Diego got a little closer to that goal by creating a miniature version of a human liver using 3-D printing. In the lab, the livers managed to perform all of the functions of a natural liver for up to 40 days — an achievement that easily surpasses previous attempts to create an artificial liver, all of which failed within a few days.
Although more work needs to be done to improve the lifespan of these livers, the fact that they are able to perform all of the major functions of the organs, including protein and cholesterol production, as well as breaking down toxins such as alcohol and medications, is quite incredible. The livers are printed using hepatocytes (functional liver cells) on a bioengineered support structure.
3-D printing is a promising approach to tackling the problem of growing complex organs such as kidneys, lungs and livers in the lab. By using a 3-D-printed scaffold, cells can be grown in exactly the places where they are needed in order to create intricate structures that closely mimic those that develop naturally in the body.
If transplanted organs are to thrive in the body, they must have an adequate supply of oxygen, which is provided through blood vessels. 3-D printing could allow extremely tiny blood vessels to be grown, improving the blood supply in organs and tissues.
The BioRap project, which is being carried out at the Fraunhofer Institute in Germany, has made good progress in tackling the problem of creating artificial capillaries using a precise laser-printing technology.
Medical implants are not limited to structures that are copies of natural organs or tissues. Many patients rely on pacemakers to keep their hearts beating to the correct rhythm. 3-D printing could radically alter the ways these devices look and function.
Researchers at Washington University and the University of Illinois have found a way to create a thin silicon membrane that wraps around the heart and monitors its rhythm, delivering impulses to keep the heart beating correctly. This design eliminates the need for wires to connect the device to the heart, which are a common point of failure.
The medical implant industry is in many ways the perfect candidate to reap the benefits of 3-D printing. One of the main benefits of 3-D printing is its ability to build precise shapes based on custom designs. This is of great importance in the medical implants industry, where every implant must exactly fit the patient who will receive it.
3-D printing also opens up the possibility of engineering complex structures such as organs from cells that are practically identical to the patient’s own tissue. Medical care could be revolutionized by the ability to replace worn-out body parts with advanced printed prosthetics.