Printing a Three-Dimensional Patient-Specific Safety Device for Reducing the Potential Risk of Mental Nerve Injury During Transoral Thyroidectomy.

BACKGROUND: Thyroidectomy transoral endoscopic thyroidectomy vestibular approach (TOETVA) is a safe and cosmetically appealing alternative for well-selected patients undergoing thyroidectomy. However, during TOETVA, placement of the two lateral trocars and/or manipulation of the surgical instruments through the trocars may potentially injure and/or compress the mental nerve (MN) because the actual location of the nerve foramen may vary among individuals. The MN injury rate was reported to be as high as 75% in the initial period of robotic-assisted TOETVA. To reduce the potential risk of MN injury, we implemented a three-dimensional printing technology to develop a safety device for TOETVA. METHODS: The patient-specific safety device (PSSD) was a brace with an exact fit to the lower teeth and two safety markers on each side to indicate the location of the mental foramen. For patient in whom the brace would not be applicable, a 3D mandibular model was printed as a PSSD instead. We analyzed 66 patients undergoing TOETVA at our institution from March 2017 to March 2019. The preoperative details and complication profiles were also analyzed. RESULTS: With incorporation of the PSSD into our TOETVA procedure, there have been no cases of MN injury. CONCLUSIONS: Our own TOETVA series has demonstrated that the implementation of the PSSD has been successful in preoperatively identifying and preventing the potential risk of MN injury. Although the additional requirements of preoperative CT and time for fabricating the device impose limitations, the influence of the PSSD in TOETVA is positive.