Cartilage, Tendons, and More—in the Palm of Your Hand

Students explore 3D printing for the human body

As a manufacturing technique, 3D printing is rapidly revolutionizing healthcare and medicine as it translates digital designs into customized devices, including hearing aids and teeth aligners.

It’s also a technology ripe for innovative ideas to improve patient care, as demonstrated by students in 3D Printing the Human Body, a School of Engineering class taught this spring by Vincent Fitzpatrick, a research assistant professor, and Xiao Kuang, a lecturer, both in the Department of Biomedical Engineering. 

Consider, for instance, one student team’s solution for osteoarthritis: Using an organic ink made from brown algae compounds, they printed a copy of a meniscus—the c-shaped cartilage that cushions the knee joint—that, once inserted, could help a patient regenerate lost cartilage.

Or how about medical devices? One team, having observed hernia surgeries as Union College undergraduates, designed a prototype for a clamp that would be easier to hold and maneuver than current models, securing incisions more efficiently and with reduced chance of tissue damage.           

Those are just two ideas from a class that aims to spark invention, said Fitzpatrick, who originated the course in 2021.

3D printed meniscus

Student 3D printing projects included addressing osteoarthritis: Using an organic ink made from brown algae compounds, the student team printed a copy of a meniscus—the c-shaped cartilage that cushions the knee joint—and that, once inserted, could help a patient regenerate lost cartilage. Photo: Alonso Nichols

“I tell students: my goal is not to make you an expert,” said Fitzpatrick, who came to Tufts as a postdoctoral scholar to work in the lab of Stern Family Professor David Kaplan, a world leader in the customized engineering of tissue and biomedical implants from silk; Kaplan and colleagues, for example, have designed silk-based biodegradable ear tubes.

With the enormous potential of 3D printing to transform medicine, Fitzpatrick sees the class as an opportunity for students to get comfortable with an exciting and rapidly evolving technology. 

“Our goal is to prepare students for what’s coming,” he said. 

A comprehensive overview for beginners, the course introduces students to many advantages of 3D printing for medical applications and patient-specific needs: it’s effective, low-waste, and relatively quick, and materials can be controlled to create a wide variety of customized or patient-tailored geometries, including hollow parts with internal truss structures.

The foundation of the course is demonstrating 3D printing in action, defined most simply as making three-dimensional products from a computer-aided design (CAD).  For human anatomy, the students often use scans of healthy bones, for instance, that can then guide the structure of an implant. 3D printing has also been called “additive manufacturing” because the procedure involves adding layer upon layer of a material; commonly, that material is plastic, but sustainable or “green” inks (such as from algae) are rapidly gaining interest. 

Tufts 3D printing student Will Pannos

Will Pannos, E25, shows lecturer Xiao Huang an Achilles tendon prototype he made for a team project in 3D Printing the Human Body. Photo: Alonso Nichols

The courses focuses on the chemical, biological, and mechanical properties of different materials, and their suitability for different applications, which then informs ample hands-on opportunities to practice making small projects based on anonymized patient data. 

The syllabus also features guest speakers who are pushing the 3D printing boundaries, such as an entrepreneur from PSYONIC, a company that has developed the world's first touch-sensing bionic hand. 

“What's valuable about guest speakers is that they describe how they went from just a cool idea they wanted to explore to something that actually works,” said Fitzpatrick. “There's the aspect of creativity and allowing yourself to dream of something and then working it into existence that I think students relate to.”

In the final three weeks of class, student teams tackle specific projects of their choosing. 

For Will Pannos, EG25, the challenge was complex: to create an Achilles tendon for a prosthetic. The project involved printing not only a hard frame required for the prosthetic foot and leg, but also a model of a tendon that would afford crucial flexibility and elasticity to support mobility and balance.

3D printed Achilles Tendon made in Tufts class

Will Pannos, E25, with the Achilles tendon his team made in 3D Printing the Human Body this past spring. The team focused on creating a model with flexibility and resilience on par with that of ligaments found in the body Photo: Alonso Nichols

Using thermoplastic polyurethane, or TPU, Pannos and his team tried printing two tendon versions, each with different elastic properties. With fine-tuning, the students arrived at one with excellent mechanical resilience on par with that of ligaments found in the body.

“Initially we were thinking we'll make some tendons and then see when they break,” said Pannos. “It turned out we couldn't even break it; it was really strong.” 

Such assembled 3D printed plastic pieces could have tremendous impact for patients faced with the high cost of prosthetics. “You don’t need some fancy facility to fabricate this kind of model,” he said. “If you have a 3D printer, you could make this anywhere out of materials that are relatively accessible and low cost.”

Zixin Ye, EG25, was on a team that looked at a solution for bone fractures. When bone fracture exceeds more than two centimeters, it’s difficult for a bone to heal on its own. The team envisioned 3D printed bone scaffolds that could provide a temporary structural framework to support the gap and allow bone cells to grow.

This type of porous scaffold should mimic the natural bone density gradient-and it would have to be strong, biodegradable, and biocompatible (non-toxic and nonallergenic). It would also need to have good porous structure to facilitate the growth of new cells. 

3D printing human body dental application

Above, Emily Pallack, Ph.D. student at the School of Engineering, shares the idea behind a customized surgical training tool that could help dental surgeons plan complex procedures. The team, including Mali Kaminaga, EG24 (shown holding the model), and Ayman Banjar, a dental research doctoral student at the School of Dental Medicine, printed bioengineered bone scaffolding, which can help regenerate the bone that supports teeth and dental implants. Photo: Alonso Nichols

This team worked with stereolithography, or liquid resin 3D printing, known for offering speed, high resolution, and smooth surface finishes. The approach helped them create a 3D-printed scaffold with triangular “pores” they believe would optimize cell growth and patient recovery. 

“For actual use, we still need experiments to verify the cell viability and adhesion rate within this microstructure,” Ye said, “but if suitable, this internal structure could be adjusted to create customized scaffolds for a variety of bone breaks.”

Ye said the experience has not only deepened her understanding of 3D printing, but also reaffirmed the joy she takes in complex problem solving. “Creating things with 3D is fascinating,” she said, “and you can quickly take an idea and test it in the real world.”

Pannos was originally a little nervous as a newcomer to the CAD software required to design 3D models prior to printing output. “But then I fell in love with it,” he said. “I came away feeling empowered to be able to say, 'OK I've got an idea in my head. I can write it down, I can open up my laptop and I can translate that idea into a design, and then, a few hours later, I can hold my thought in my hand.'”

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