3-D printing techniques to help surgeons carve new ears

Researchers have used 3D printing techniques to create a low-cost paediatric rib cartilage model using a new material, which could be employed by surgeons to practice carving out new ears.
To treat children with a missing or under-developed ear, surgeons harvest pieces of rib cartilage from the child and carve them into the framework of a new ear.
However, medical residents don't have authentic material to practice on, as vegetables are a pale substitute.
Some use pig or adult cadaver ribs, but children's ribs are a different size and consistency.
The innovation could open the door for aspiring surgeons to become proficient in the sought-after but challenging procedure.

"It's a huge advantage over what we're using today," said lead author Angelique Berens, from the University of Washington School of Medicine.

As part of the study, three experienced surgeons practiced carving, bending and suturing the silicone models, which were produced from a 3D printed mold modelled from a CT scan of an 8-year-old patient.
They compared their firmness, feel and suturing quality to real rib cartilage, as well as a more expensive material made out of dental impression material.
All three surgeons preferred the models, and all recommended introducing them as a training tool for surgeons and surgeons-in-training.
Kathleen Sie, a professor at University of Washington, said the lack of adequate training models makes it difficult for people to become comfortable performing the delicate and technical procedure, which is called auricular reconstruction.

Another advantage is that because the models are printed from a CT scan, they mimic an individual's unique anatomy.
That offers the opportunity for even an experienced surgeon to practice a particular or tricky surgery ahead of time on a patient-specific rib model.
Co-author Sharon Newman, who was a student at University of Washington during the research, figured out how to upload and process a CT scan through a series of free, open-source modelling and imaging programmes, and ultimately use a 3D printer to print a negative mold of a patient's ribs.
Newman had previously tested different combinations of silicone, corn starch, mineral oil and glycerin to replicate human tissue that the lab's surgical robot could manipulate.

She poured them into the molds and let them cure to see which mixture most closely resembled rib cartilage.
"With one 3D 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," said Berens.