On March 12, 2020, Danish startup Particle3D developed a new 3D printed bone implant. They pioneered a new method for 3D printing lightweight custom bone implants that fully fused with bone before slowly disappearing. This technology has a low risk of infection and the implant is tailored (the method may soon go into space with astronauts!).
Custom "bio-ink" opens up many possibilities
Traditional implants usually consist of non-degradable materials, such as polymers or titanium alloys. Particle3D uses a "bio ink" made from tricalcium phosphate (TCP) powder particles and fatty acids. TCP has been used for decades in reconstructive surgery, but is usually manually carved by surgeons from solid blocks into the desired implant shape. For example, this approach may limit the benefits of TCP when stimulating natural bone growth.
Particle3D works by scanning the patient's bones or the area where the implant will be placed. The data is entered into a computer program, and surgeons and staff can use CAD computer models to optimize implant design. The customized implant is then printed by Particle3D and sent to the hospital for implantation.
3D printing TCP enables the company to make more porous implants. The porous structure allows the implant to act as a scaffold for the growth of blood vessels and natural bone, and the implant will degrade over time as the implant is replaced by the natural bone. Tests in pigs and mice have shown that new bone marrow and blood vessels appear in the implants after just eight weeks.
3D printing and healthcare
The use and manufacturing of 3D printing in the healthcare field is gradually moving from rapid prototyping to mass production.
3D printing in early healthcare, use cases include printing 3D models of bones, body parts and organs before surgery, enabling surgeons to better visualize and practice before surgery.
Customization, cost reduction, time to market and distributed production are the advantages of 3D printing in the healthcare field. 3DP4ME is a good example. It is a non-profit organization dedicated to bringing hearing aids to millions of people in developing countries who currently cannot afford them. Through 3D scanning, 3D modeling, and 3D printing, the nonprofit hopes to provide 12,000 tailored hearing aids in countries such as Jordan over the next five years.
Store medicine in your bones
For 3D printed bone implants, one of the benefits is that the chances of infection and postoperative complications are low. Given the scope of the implantation procedure (generally incision of the skin to insert the implant), the risk of infection will limit the surgery and subsequent recovery stages. Some polymer or titanium implants must be removed again later, which requires a second operation. Implants can also cause complications, such as limited limb use or chronic pain.
Create an accurate copy of the complex three-dimensional structure of the bone, which can be gradually degraded by the human body during recovery, which can save the patient from secondary surgery and permanent health problems.
Compared to traditional implants, Particle3D implants can also store drugs in porous materials for longer. Traditional implants are usually coated with antibiotics before insertion, but these will wear out within a few days after surgery.
But there are some disadvantages to using porous TCP to print bones. Its compressive strength is much lower than that of some human load-bearing bones, such as our thigh bones. Compressive strength increases over time, but it may take years to reach the strength level before surgery.
Future 3D printed bones?
Several other groups are working on similar methods. At NYU School of Medicine and NYU Langone Health Hospital, scientists have been developing 3D printed stent implants that can help patient groups such as children with skull deformities. Earlier studies showed that up to 77% of bone scaffolds were absorbed by natural bone and replaced by natural bone at 6 months after surgery, and newly grown bones were as strong as the original bones.
However, most research groups find themselves at the same stage as Particle3D, admonishing people that using the technology in humans may take years. This is partly due to regulatory approval issues regarding 3D printed biomaterials for human use. Medical approval is usually a long process, so it may take longer to actually apply it to the clinic.