The University plans to take its 3D pringing initiatives one step further.

The University has signed a license agreement with Materialise, a 3D printing and software company headquartered in Belgium, to commercialize 3D-printed tracheal splints developed at the University.

The splints already saved the lives of four children, and are used to mitigate complications associated tracheobronchomalacia, a condition resulting from the malformation of vascular structures in a person’s airway. The malformation can result in a weakened trachea or bronchi, which can cause the airway to become too narrow or collapse.

According to Scott Hollister, a professor of biomedical and mechanical engineering, tracheobronchomalacia occurs once in every 2,200 births. In the United States, that averages about 1,500 to 1,800 patients a year with the condition, with ranging severity. While some kids with a mild form of the condition will not need medical intervention, those with moderate to very severe forms require treatment that can potentially be life-saving.

“The kids exhale, which puts a negative pressure in the airway that tends to want to collapse the airway,” he said. “With normal cartilage it will hold up the airway, but with these kids it collapses completely and they can’t get air out of their lungs.”

Hollister said he began working with 3D printing technology as an approach to treating the condition when he met Glenn Green, an otolaryngologist at C.S. Mott Children’s Hospital, in the summer of 2011. Green suggested working on an external device that could directly treat tracheobronchomalacia.

The splint used for tracheobronchomalacia is three-quarters of a cylinder, with a small opening on one side of the cylinder. Since a person’s airway is similar to a tube, and part of that tube is collapsing, the splint is placed surgically on the exterior of the airway to pull the airway open.

“We do a CT scan for the child prior to the surgery, and so when the child exhales we can see where the collapsed segment is and how long the collapsed segment is,” Hollister said. “Then from the inhalation scan, we get an idea from the diameter of the collapsed region under inhalation pressures.”

The doctors take measurements from both scans and use those measurements to design the splint. While all splints have the same general geometry, the diameter and the length of the cylinder are customized for each patient.

Hollister said the doctors were worried about whether or not the splint would allow for growth of the patient over time. To address this challenge, doctors took periodic imaging to look at the size of the airways, and determined that airways still grow, even with the attached splint.

Hollister said he was already familiar with Materialise, as he had previously used their software to teach a class and employed it while developing the splint.

Hollister said the company contacted him upon hearing about the first procedure using the splint in 2013, and wanted to help develop the technology for clinical use. The company, which has a branch in Plymouth, Mich., used its technology to help design the customized splints. Since Green and Hollister work on the project through the University, Materialise needed to work with the University to come up with a licensing agreement for the technology.

“This agreement is a critical step in our goal to make this treatment readily available for other children who suffer from this debilitating condition,” Green said in a press release.

Polycaprolactone, the material used to make the splints, is bioresorbable, so fluids in the body will cause the polymer to break down over time. This particular polymer takes about three to four years to be completely resorbed by the body, making a repeat surgery unnecessary.

While currently the technology is not approved by the FDA, the agency has given clearance to use it for emergency life-or-death cases. The splint has been implanted in four children, all of whom were between about three and 16 months of age. The doctors reported that the patients all responded well to the surgery.  

“Here at Materialise, we strongly believe in the transformative power of great collaborations, such as the one we have enjoyed these past two years with Dr. Green, Dr. Hollister and all others who have contributed to this life-saving application of 3D printing,” said Bryan Crutchfield, managing director of Materialise U.S.A. in a press release. “This collaboration is proof that when the right skill sets and technologies are combined, solutions can be found for problems once thought impossible.”

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