RESUMO
Objective To study effects of the bacterial biofilm at different growth stages on dynamic behavior of the titanium partial ossicular replacement prosthesis (PORP), so as to provide theoretical references for clinical treatment of diseases such as secretory otitis media. Methods Based on the CT scan images of normal human right ear and combined with the self compiling program, a 3D finite element model of the ear was reconstructed for dynamic analysis on sound conduction, and compared with the experimental data. The model was computed by harmonic response analysis method, and the sound conduction effect of bacterial biofilm grown on PORP at different growth stages was analyzed. Results The simulated amplitude of umbo and stapes footplate was in accordance with experimental measurements, which confirmed the validity of this numerical model. The existence of biofilm would cause 0-1.6 dB hearing loss at low frequencies. The growth of biofilm in the radial direction of PORP would cause 0-12 dB hearing loss at intermediate and high frequencies, especially at 8 kHz, and the hearing loss could be as high as 11.2 dB. Conclusions The bacterial biofilm has an impact on hearing by reducing the hearing at low frequencies while raising a little at high frequencies. The biofilm grown in the radial direction of PORP will reduce hearing, and affect the working efficiency of PORP on hearing restoration.
RESUMO
Objective To study the postoperative effects on hearing restoration after different types of ossicular reconstruction with partial ossicular replacement prosthesis (PORP). Methods CT data of the right ear from a healthy volunteer were digitalized and imported into PATRAN software to reconstruct the 3D finite element model of the ear by a self compiling program. Dynamic analysis was conducted on the sound transmission to make comparison between the calculated results and experimental data. Results Results of the dynamic analysis for normal human ear were in good agreement with the experiment data, which confirmed the validity of the FE model. At the frequency between 0.1~10 kHz, hearing restoration with partial retaining the handle of malleus was better than that without retention after the replacement of PORP, and the value of hearing restoration was between 11.56~28.91 dB. The maximum stress of tympanic membrane with partial retaining the handle of malleus was less than that without retaining. At the frequency between 0.1~0.6 kHz as well as between 2~10 kHz, better hearing restoration was obtained when the thickness of the cartilage slice was 2.0 mm. At the frequency between 0.6~2 kHz, better hearing restoration was obtained when the thickness of the cartilage slice was 0.1 mm. Conclusions For ossicular reconstruction with PORP, the effect of retaining the handle of malleus was much better than that without retaining. The effect of hearing restoration was better when the thickness of the cartilage placed between the tympanic membrane and the contact surface of the PORP was within the range of 0.1~2.0 mm.