Additive manufacturing (AM) has undergone a major evolution since the early 2000s, when it was first used to produce dental implants and custom prosthetics. Today, with its ability to fast-track the creation and production of complex geometries that mimic the form and function of natural biomechanics, AM is rapidly transforming healthcare.

In recent years, 3D printing has solved some of the biggest challenges in the field of orthopedics. Before it was possible to quickly produce custom implants, surgeons often needed to modify standard implants to fit some patients by conforming the patient’s body to match the implant. Today, we are getting closer to producing implants that match the patient before going into surgery.

Now, AM is making it possible for surgeons to accomplish tasks that were previously impossible. After creating digital print files from patient x-rays, CT or MRI scans, production of a complex, patient-specific metal implant can be completed, often in less than 24 hours.

Throughout the history of AM, there have been many commercial and clinical successes. In 2012, researchers at the BIOMED Research Institute in Belgium implanted a 3D-printed titanium mandibular prosthesis in an 83-year-old patient. 2013 saw the first successful implantation of a 3D-printed polyetherketoneketone (PEKK) skull implant. Fast-forward to 2024: AddUp Solutions and Anatomic Implants are collaborating on the first 3D printed toe joint replacement. 

With all the benefits it offers for the future of personalized healthcare and improved patient outcomes, the application of AM in orthopedics promises to be a game-changing development. 

From subtractive to additive manufacturing

Traditional subtractive manufacturing methods have always had limitations in the geometries they can produce. They also require significant amounts of time for machining, particularly when working with materials like titanium. 

By enabling the layering of materials to manufacture objects from 3D model data, AM makes it possible to create complex shapes and structures not possible before. It has provided a cost-effective new approach to producing medical implants tailored to the unique anatomy of individual patients, providing significantly greater design freedom and control without the need for tooling or molds.

“With traditional processes, there is a need for post-production surface treatments with porous sprays, whereas 3D printing makes the production of implants with highly porous structures possible,”  says Tyler Antesberger, medical application engineer at AddUp Solutions. “So, it’s definitely a value-add that with AM, you have complete control of the device down to the micron—not just applying something to the surface and hoping that it works.” 

From metals to biocompatible materials

The use of metal-based AM for producing medical implants has been on the rise for many years. Materials used in manufacturing medical implants must meet many requirements, including high strength for functioning for long periods, corrosion and wear resistance, and biocompatibility and biodegradability.

“There’s a lot of talk around biocompatibility,” says Antesberger. “There are a lot of studies about cell scaffolds and things like that—how does bone actually grow into these devices and become part of the body?” AM makes it possible to design highly complex, customized designs that match a patient’s anatomy—and to create lattice structures that are needed to create the porous surface needed to improve bone integration in the human body. AddUp’s roller coater technology makes it possible to create an implant with a smooth surface finish with fine features and lattice resolutions.

While many advances have been made in the use of 3D-printed metallic biomaterials for use in implants, there are currently only a few metals that can be used. Today, about 75% of medical implants are made from stainless steel, titanium alloys, cobalt-chromium alloys, niobium, nitinol and tantalum—with the use of magnesium, zinc, iron, and calcium on the rise.[1]

“The primary material used now for medical implants is Grade 23 titanium,” Antesberger says. “It has a lower oxygen content than other titanium on the market and good biocompatibility. A few other materials used in 3D printing are stainless steel alloys.”

Expanding what’s possible

The promise of 3D-printed implants for the future of personalized medicine is bright. Healthcare institutions like the Mayo Clinic already have launched large-scale 3D printing labs where they produce patient-specific 3D-printed orthopedic braces and surgical tools. And we may soon see a future in which hospitals are producing 3D-printed, patient-specific medical devices on-site at the point of care.

“Hopefully, in the future, additive manufacturing in healthcare will allow us to create a customized design for every individual—to help reduce the time in the hospital, reduce recovery time, and increase the life of the implant,” Antesberger concludes.

[1] https://www.sciencedirect.com/science/article/pii/S266652392300096X