Oct 1, 2015 | By Alec

With medical innovations being developed at breakneck speeds nowadays, it is sometimes very surprising to learn that some medical procedures still require so much manual guessing work. Case in point is ear surgery on children and adults who were born with an underdeveloped ear, a condition that is almost impossible to fix perfectly. Fortunately, a new study by two scientists from the University in Washington have come up with a clever solution, in which 3D printing is used to make perfect surgical ear models as reference guides during surgery.

The problem in this field is inherent in the reconstruction method. Ears are almost completely made out of cartilage, and whenever a child enters surgery, surgeons harvest cartilage from their rib cages and immediately carve a new ear from it in a single session. Because the supply is so precious, they only take as little as they need and do the best they can with the limited time and supplies available. The result is an ear that doesn’t look fantastic, but surgeons typically practice on other materials. A bar of soap, a carrot, an apple, even pig cartilage is used to practice carving. However, none of these materials are of the same size and consistency, or have the necessary characteristics, to make this a realistic practice session.

Fortunately, this new study presents a clever solution. The result is presented at the American Academy of Otolaryngology — Head and Neck Surgery conference in Dallas later this week, but the developers Angelique Berens (otolaryngology resident at UW) and bioengineering graduate Sharon Newman already explain the concept. The concept itself was developed in the UW BioRobotics Lab under professor Blake Hannaford. Clinical associate professor Craig Murakami and assistant professor David Zopf were also involved.

Their solution is remarkably simple: 3D print a low-cost rib cartilage model that resembles the look and feel of a real human cartilage, enabling surgeons to practice the coming procedure. ‘It’s a huge advantage over what we’re using today,’ Berens says. ‘You literally take a bar of Lever 2000 while the attending is operating and you carve ear cartilage. It does teach you how to get the shape right, but the properties are not super accurate — you can’t bend it, and sewing it is not very lifelike.’ Instead, CT scans were made of an 8-year-old patient, which was used for a 3D printed silicone test model.

To test the result, the firmness, feel and suturing quality of the model was compared to that of real cartilage and of the far more expensive dental impression material – also a common choice for practicing. Presenting them to three surgeons for practice, all argued that the 3D printed model was far superior as a training model.

The hope is that this method will make the ear reconstruction surgery (known as auricular reconstruction) easier and quicker. As professor Kathleen Sie said, there is currently a six to twelve month waiting list for the procedure at the Seattle Children’s Hospital. ‘It’s a surgery that more people could do, but this is often the single biggest roadblock. They’re hesitant to start because they’ve never carved an ear before. As many potatoes and apples as I’ve carved, it’s still not the same,’ she says.’

Another advantage is that these models very closely mimic a patient’s own anatomy, as 3D printed surgical models based on CT scans typically do. That enables every surgery to be prepared for each indivial patient, greatly reducing the risk of complications. And of course, it’s much cheaper. 'With one 3-D printed mold, you can make a billion of these models for next to nothing,’ said Berens. ‘What this research shows is that we can move forward with one of these models and start using it.’

Remarkably, this entire process grew out of the free modeling software we all typically use. Newman just uploaded a CT scan into a number of programs and experimented a bit, before taking it to a 3D printer. Newman previously tested a number of molds filled with materials such as silicone, corn starch, mineral oils and different combinations thereof. ‘I would go to the craft store and Home Depot and say I want to make models — what aisle should I go to?’ said Newman. ‘It turns out a lot of these ideas were based off of materials people use for arts and crafts like rings or other jewelry.’

The next step is to spread these models and manufacturing methods throughout the surgical world, and let them do their magic. It’s remarkable how a bit of simple 3D printing could be so effective when people’s lives are taken into consideration.



Posted in 3D Printing Applications





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David Zopf wrote at 10/3/2015 12:32:07 PM:

Mason: Excellent question. I am the senior author on the project. We have already produced and tested tissue engineered 3D printed tissue scaffolds for implantation. They are amazing. However they need to undergo FDA approval before clinical use. While that process takes place, this will help improve current clinical practice. David A. Zopf MD, MS Assistant Professor Otolaryngology - Head and Neck Surgery Pediatric Division University of Michigan davidzopf@med.umich.edu

Mason Sheffield wrote at 10/1/2015 11:51:05 PM:

Why not just CNC machine the Cartilage into ear shape instead of hand carving?

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