Three-dimensional finite element analysis of the human middle ear and an application for clinics for tympanoplasty

Abstract

The geometric model around the middle ear which includes the tympanic membrane, tympanic cavity, auditory ossicles, several ligaments, and tensor was constructed using SolidWorks. The auditory ossicles consist of malleus, incus and stapes. The computerized tomography (CT) scan data around the middle ear was converted into DICOM (Digital Imaging and Communication in Medicine) data, then into STL data. This STL data was imported to SolidWorks in order to generate the geometric model. The sound pressure through the tympanic membrane was applied to this model in a three-dimensional finite element analysis using COSMOSWorks. Then, the mechanical influence of the sound pressure upon the middle ear was analyzed. The deformation of the middle ear and the displacement of the stapes under the sound pressure of 120 dB were clarified. The displacement of the bottom of the stapes in the direction of the axis is about 3.1 nanometers which becomes a standard value of the hearing ability evaluation. In the internal ear, the stapes vibration is transmitted to the labyrinthine fluid in the cochlea where electrical signals are generated. Finally, it is recognized in the brain as sound. For example, in the case that the medical device is substituted for the deficient auditory ossicles, it is possible to estimate hearing ability by comparing to what degree the displacement of stapes changes. This kind of approach makes it possible to propose a new medical treatment for the recovery of conductive hearing loss. © 2013 WIT Press.