3D Printing Bones Is Changing the World of Medicine
While 3D printing is a technology that is relatively in its infancy, it’s already been adopted into numerous fields, and is today used in architecture, modelling, electronics, production, and even medicine. The ability to quickly design and create a product to-specifications is incredibly valuable in the field of medicine, and it’s already been adopted into several hospitals around the world. In fact, there are already people walking around today with 3D printed bones and implants.
How it Works
The technology is actually remarkably similar to existing implant methods, and typically uses the same titanium used for other implants. The difference is that instead of carefully sculpting or molding the replacement bone implant, it can be designed to specs using a computer and then simply ‘printed’ out quickly.
These titanium 3D printed bones have been used in multiple patients, starting with a 12 year old boy in August of 2014, following extensive trials at the Peking University Third Hospital’s Orthopedics Department. The boy received an implant printed in titanium powder. But, why 3D printing when we already use titanium implants? 3D printing allows for precision structures to be created inside of the implant, to better mimic the bone, and to add increased strength and improved shape, so that the implant goes in more easily. For example, 3D printing can achieve curves not possible in other forms of shaping titanium, which creates a better fitted final result.
In fact, this type of 3D printing is now so common that it’s been used in multiple hospitals around the world. While not yet common practice, it’s being adopted, and quickly.
But, rather than relying on titanium alone, new studies released this year have proven that the best results are achieved using combinations of bone, biomaterial, and plastics or titanium metals. In fact, one study published by the John Hopkins University released data from a study on mice, showing that the current most effective solution is a combination of PCL (a biodegradable plastic), pulverized bone (from cows in this case, decellularized to remove all but the basic protein building blocks)), and mixed into solutions that can then be printed using the same lattice shaped structure found in natural bone to create a sort of scaffold intended to allow natural bone growth over it. This combination allows the cells in the 3D print to grow, especially when prepared for the human body. During the study, 3d printed ‘bones’ were bathed in a nutritional broth with human fat cells (taken from liposuction patients) to encourage growth. With a 70% bone to PCL mixture, natural bone growth was over 300% higher after 3 weeks than with a PCL only scaffold. These materials were then used to close holes in the skulls of mice, which would not have closed naturally on their own. And, in all of those studies, the mice had natural bone growth over the hole within 12 weeks.
The same technologies are already being commercialized in Europe, where technologies like CT-Bone, which is a brand producing implants that are eventually replaced by natural bone, are set to hit the market soon. CT-Bone was developed by Xilloc Medical (A Dutch company) and Next 21 (a Japanese company) pioneered techniques to use CT scans of patients to create exact replicas of the missing bone piece, including spaces for blood vessels, fat, and tissue. These implants are then printed out using a mixture that is primarily natural bone, implanted, and integrated into the human body. These technologies are important in that they would allow the implant to eventually grow over with natural bone to replace the implant, while also reducing the chances of rejection, infection, and other issues.
Both Wake Forest Institute for Regenerative Medicine and the University of Waterloo are working on surprising developments including customized 3D printers which allow doctors to print replacement cartilage, joints, and other previously difficult to replace body parts. At the University of Waterloo, Bob Pilliar and Mihaela Vlasea 3D print a scaffolding with Calcium polyphosphate as the primary material. This biodegradable material actually makes up about 70% of the natural bone, which means that as the scaffolding breaks down inside of the human body, it encourages natural bone growth and provides the basic materials to build it from. Working with Dr. Rita Kandel is the chief of pathology and laboratory medicine at Mount Sinai Hospital, they were also able to break other boundaries. Dr. Kandel was able to literally synthesize cartilage by extracting bone marrow from the patient and then building immature cartilage cells from their own tissue. This process would allow joint replacement to become safer and more durable, because the replacement tissue would be part of the patient’s body. While not yet viable, Dr. Kandel suggests that it should be available within a decade.
And, at the Wake Forest Institute for Regenerative Medicine things get even more interesting. Their custom 3D printer works with cartridges that include living tissue and cells and prints inside of a nutrient gel. After maturation, the muscle, bone, cartilage, and skin that this printer is capable of producing can be implanted into an animal (or human) where it can merge with the body and survive indefinitely. In fact, this 3D printer is the world’s first printer capable of producing living tissue large enough to be implanted into humans. The printer, or the Integrated Tissue and Organ Printing System combines the cells required for the body part with a polycaprolactone scaffold (similar to all of the other technologies here) to hold the tissues in place. And, because it’s biodegradable, it eventually disintegrates to leave nothing but healthy replacement bone or flesh.
3D printing has come a long way, and it’s future in the medical industry is undeniably exciting. Still, some people have qualms about having 3D printed anything inside of them, and many others dislike the idea of using cells grown outside of the human body. Despite that, 3D printing bones and other human body parts will allow for unparalleled advances in surgery, recovery, and long-term health after transplants. What do you think?