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3D Printed Finger Models Advance Medical Education

“Twenty years ago, I started making models out of wood,” Dr. David Greene, a biomechanics professor in CSU’s Occupational Therapy department, said of his earliest ideas for a model of human fingers. Dr. Greene used handmade models in graduate school, where he realized the value of using these tools in human anatomy. Dr. Greene’s class, which focuses on understanding function by studying the relationships of muscles to joints, tested the 3D printed model last summer.

Dr. Greene's finger model grasps a cup exactly as a human hand does Photo courtesy David Greene

Dr. Greene’s 3D printed finger model grasps a cup exactly as a human hand does when muscles are activated correctly
Photo courtesy David Greene

The 3D printed model focuses on three joints within the finger, and students must attach strings, which act as muscles, to properly move the joints. “There are things you can’t read in any book. Some things students have to discover through interacting with models.” Even though dissections are a common tool used by anatomy students, cadavers alone cannot teach much about motion. Trying to simulate injury using the student’s own bodies works poorly as well, since our bodies are incapable of using only one tendon at a time.

With the 3D printed model, students can remove a string entirely, simulating a cut or damaged tendon in a patient, and note the change in balance in the finger. Using a model this way can help students better understand and treat injuries in patients. The 3D printed models can also simulate structural failures that occur in degenerative diseases.”There is a hand muscle that slips out of place, leading to joint dislocation, in rheumatoid arthritis. Because the 3D model’s design is true to actual biomechanics, it is able to naturally simulate the same problem so that it occurs in the model just like it does in the human body,” Dr. Greene said.

With these models, students can see what a specific mechanism does, and realize what needs to work with it in order to perform a movement correctly. Students don’t have the tools to make their own models, and even when Dr. Greene provided them in class, they would spend more time building the models than learning from them. While Dr. Greene was working on another project with Idea-2-Product, he saw how 3D printing could help produce his models. “I saw some models Zach (Carrizales) was working on, and showed him my wooden fingers. Zach designed the new model by combining concepts of my wooden prototype with work he was already doing for a prosthetic hand design. What’s amazing is they’re printed articulated already.”

A student manipulates the strings, which act as muscles, to flex the finger model Photo courtesy David Greene

A student manipulates the strings, which act as muscles, to flex the finger model
Photo courtesy David Greene

There are still some designs that Dr. Greene wants to expand. “The current model is wonderful for this introductory class, which is about the relationship of muscles to joints, resulting in activity as we observe it. For example, flexing the finger around an object requires a small intrinsic muscle to first extend the distal two joints, while flexeing the metacarpophalangeal joint, and the model simulates this perfectly.” Once the students have passed their strings through the model in the correct relationships to the joints, they practice closing the model around large and small objects. Understanding these intrinsics in the 3D printed model can help students understand problems real patients with nerve damage experience in grasping objects. “This is a strictly mechanical problem,” Dr. Greene said, “and the model demonstrates this perfectly. With a small revision we can also demonstrate Boutonniere injury, another mechanical problem related to a muscle’s relationship to a joint. Developing models that simulate soft-tissue injuries, like trigger finger, will be more challenging, as will multijoint wrist-finger models that would demonstrate normal and abnormal grasp.”

The 3D printed finger models can help medical students, and have the potential to expand and incorporate electronics Photo courtesy David Greene

The 3D printed finger models can help medical students, and have the potential to expand and incorporate electronics
Photo courtesy David Greene

Even though his 3D printed finger models were only recently incorporated into a classroom, Dr. Greene hopes the models can continue to advance the education of occupational therapy students working in medical settings. “My ultimate goal would be a programmable motor-driven model that would provide the cognitive challenge of programming, but also opportunities for kinesthetic learning through pulling on different strings to produce the desired motor sequence. I know 3D printing would be a part of that,” Dr. Greene said. One of Dr. Greene’s students even designed and built a complex shoulder model that involves the scapula and clavicle, which could serve as a prototype for the 3D printed programmable models. This model could answer clinical questions involved various functional movements of the arm. “It would be cool if it was something that could be widely adopted as a teaching tool.”  As medicine and engineering continue to advance, teachers like Dr. Greene will continue to incorporate the two fields for the better, by developing teaching tools and advancing education for future medical practitioners.

 

 

I2P’s Custom Wedding Ring Scan allows for Cross-Country Design

I2P’s Custom Wedding Ring Scan allows for Cross-Country Design
I2P's Ray Huff scans Lelek's custom engagement ring to assist in her wedding ring design. Photo courtesy Ray Huff

I2P’s Ray Huff scans Lelek’s custom engagement ring to assist in her wedding ring design.
Photo courtesy Ray Huff

Congratulations Etheredges! Idea-2-Product is happy to have helped during your wedding. “My fiance, now husband, gave me a custom made engagement ring from a jeweler in San Francisco,” Annie Etheredge said. The jeweler was a family friend, and had designed many pieces for them. Since the engagement ring was custom, the wedding ring had to be customized to fit as well. As the Etheredges designed Annie’s wedding band, they didn’t think they would have to ship her engagement ring in order to finish the new band’s design, but the process became tricky. “A few weeks before our wedding, the manufacturer told our jeweler they needed it before they could continue.”

Trying to ship her ring a few weeks before the wedding wasn’t really possible. “I was reluctant to send my ring through the mail so close to our wedding date and began looking at other options.” The Etheredges considered a few choices, such as submitting pictures or measuring the detailed, custom dimensions of the ring, but knew these methods wouldn’t be enough. When a fellow engineering colleague of Annie’s mentioned that Idea-2-Product not only had 3D printers, but also housed a 3D scanner, she knew she’d found the solution. Since the jeweler needed a 3D file of Annie’s ring anyway, she called his shop in California and found the Computer Assisted Design (CAD) file that the jeweler would need.

The scan of Annie Lelek's engagement ring paired with the design of her custom wedding ring (green). Photo courtesy Annie Lelek

The scan of Annie’s engagement ring paired with the design of her custom wedding ring.
Photo courtesy Annie Etheredge

“They were uneasy about the idea,” Etheredge admitted, “but agreed, and told me they needed a .stl file.” Knowing what she needed, Etheredge called Idea-2-Product, and the lab saw her the next day. “It took a few tries, but we ended up getting a scan that had all the dimensions and angles the manufacturers needed to complete my wedding band,” Etheredge said happily.

Idea-2-Product was able to place the 3D scanned image of the engagement ring alongside the design of the wedding ring. With these two files together, the lab was able to adjust the prongs and height of the wedding band so that it didn’t interfere with the engagement ring’s design, allowing the two rings to fit together perfectly. “For the first time, I was able to see how the two rings would look next to each other, which made me confident about all of our design choices.”

Annie's complete custom wedding ring alongside her engagement ring Photo courtesy Annie Lelek

Annie’s complete custom wedding ring alongside her engagement ring
Photo courtesy Annie Etheredge

After Idea-2-Product scanned and sent the file for Annie’s wedding ring, she was able to have both of her rings on her wedding day. Etheredge said, “The ring showed up two days before our wedding and it was a perfect fit! I am 100% confident that I would not have been married with my wedding band if it wasn’t for Idea-2-Product.”