Experimental study of bone tissue heating with application of cutting burrs using drill
Authors:   Saint Petersburg Research Institute of Ear, Throat, Nose and Speech,  Saint Petersburg, 190013, Russia, D’yakov I. M. , Kalyapin D. D. ,   Saint Petersburg Research Institute of Ear, Throat, Nose and Speech,  Saint Petersburg, 190013, Russia, Chernushevich I. I. ,   Saint Petersburg Research Institute of Ear, Throat, Nose and Speech,  Saint Petersburg, 190013, Russia, Goncharov O. I. ,   City Hospital N 26, Saint Petersburg, 196240, Russia, Pavlov A. V. ,   Peter the Great Saint Petersburg Polytechnic University, Saint Petersburg, 195251, Russia, Bikmulin A. V. ,   Peter the Great Saint Petersburg Polytechnic University, Saint Petersburg, 195251, Russia
Published: February 2024

The article is devoted to modeling the situation of thermal damage to the facial nerve when working with cutting burrs during otosurgical interventions. Materials and methods. 12 cadaveric temporal bones were used, in which the average tissue density was previously measured using the densitometry method. In the work, we used a drill with a speed of 12,000 rpm and 2 spherical 5 mm diameter cutting burrs with 8 and 16 cutting edges. To cool the burr and the bone surface in the affected area, automatic and manual watering with 0,9% saline solution was used. To record the temperature in the bone depth, a system of two chromel-copel thermocouples was used with real-time data recording using a National Instruments analog-to-digital converter with a recording frequency of 100 Hz. A thermal imager Bosch GTC 400 C was used to record the final temperature of the bone surface. Results of the study. The index of the average bone density of the cadaveric temporal bones used in the study varied from 287 to 499 g/cm3. Data have been obtained indicating a direct correlation between bone density and temperature rise during milling. It was found that the rate of local temperature rise during milling of 9 bone samples with a density of 287–392 g/cm3 was statistically significantly (p < 0,05) greater in experiments using the burr with 16 cutting edges compared to experiments with the burr with 8 cutting edges. However, the rate of local temperature rise during milling of 3 bone samples with a density of 402–499 g/cm3 was statistically significantly (p < 0,05) greater in experiments using the burr with 8 cutting edges compared to experiments with the burr with 16 cutting edges. The use of an automatic saline system with preferential irrigation of the burr was less effective than manual delivery with primary irrigation of the bone surface (p = 0,000317). In 10 out of 12 observations with automatic irrigation, local heating of the bone was recorded at an average rate of 0,32 ± 0,15 °C per second, while with manual irrigation only in 1 case was an increase in temperature at a rate of 0,2 °С per second, and in the remaining 11 observations no increase in temperature was recorded. Conclusions. The developed model of the experiment on cadaveric bone tissue using chromel-copel thermocouples turned out to be a convenient tool for studying thermal phenomena. The heating rate of the bone during its burring depends on the bone tissue density, the characteristics of the burr and of irrigation.