When surgical residents need to practice the complicated procedure they typically use a bar of soap, carrot or an apple to practice carving out the shape of a new ear. When performing the procedure for real, surgeons harvest pieces of rib cartilage from the child which they then carve into the framework of a new ear.
"It's a huge advantage over what we're using today," said lead author Angelique Berens, UW School of Medicine otolaryngology. "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."
Co-author Sharon Newman, UW bioengineering graduate, figured out how to upload and process a CT scan of an eight-year-old patient through a series of free, open-source modelling and imaging programs, and used a 3-D printer to print a negative mould of a patient's ribs.
Newman had previously tested different combinations of silicone, corn starch, mineral oil and glycerine to replicate human tissue that the lab's surgical robot could manipulate. She poured them into the moulds and let them cure to see which mixture most closely resembled rib cartilage.
As part of the study, three experienced surgeons practiced carving, bending and suturing the UW team's silicone models. They compared their firmness, feel and suturing quality to real rib cartilage, as well as a more expensive material made from dental impression material.
All three surgeons preferred the UW models, and all recommended introducing them as a training tool for surgeons and surgeons-in-training.
The team's next steps are to get the models into the hands of surgeons and surgeons-in-training to demonstrate that more lifelike practice models can elevate their skills and abilities.