Abstract: Objective To assess the ability of preoperative mastoid cortical bone implantation points and surrounding tissue to accept accurate positioning. Methods The study enrolled 20 sides of congenital external middle ear malformations that had undergone external auditory canal reconstructive surgery and had been evaluated with multislice computed tomography(MSCT). The control group included 20 normally developed mastoid processes that were also evaluated with temporal bone MSCT. Modeling software was used to create and mesh a three-dimensional tibial CT image for each study subject. The three-dimensional location of the premolars and tibial structure of each subject was analyzed. Results The analysis method used can perform rapid three-dimensional CT imaging of preoperative thin sacroiliac bone, precise positioning of preoperative implantation position, and evaluation of peripheral bone force conditions. After surgery for external and middle ear deformities, implantation using a ball drill at 750 rpm allowed a safe distance from the open osseous external auditory canal at a circumference of 2.07±0.05 mm. For patients without external middle ear malformations, the safe distance from the talus external auditory canal circumference was 1.83±0.07 mm, and cortical bone of the external auditory canal that has been formed will not be deformed by excessive instantaneous impact force of the drill during surgery. Conclusion This method is flexible and simple. For patients with external and middle ear deformities who have undergone auditory reconstructive surgery and wish to proceed with implantation surgery, this preoperative method can assess the mechanical effects of implantable titanium nails on mastoid cortical bone and the reconstructed external auditory canal wall.

Key words: Ear turns appendage, Finite element model, Middle ear malformation, Mechanics analysis