ObjectiveIn the field of cochlear implantation, the current trend toward patient-specific electrode selection and the achievement of optimal audiologic outcomes has resulted in implant manufacturers developing a large portfolio of electrodes. The aim of this study was to bridge the gap between the known variability of cochlea length and this electrode portfolio.DesignRetrospective analysis on cochlear length and shape in micro–computed tomography and cone beam computed tomography data.SettingTertiary care medical center.Subjects and MethodsA simple 2-step approach was developed to accurately estimate the individual cochlear length as well as the projected length of an electrode array inside the cochlea. The method is capable of predicting the length of the cochlea and the inserted electrode length at any specific angle. Validation of the approach was performed with 20 scans of human temporal bones (micro–computed tomography) and 47 pre- and postoperative clinical scans (cone beam computed tomography).ResultsMean ± SD absolute errors in cochlear length estimations were 0.12 ± 0.10 mm, 0.38 ± 0.26 mm, and 0.71 ± 0.43 mm for 1, 1.5, and 2 cochlea turns, respectively. Predicted insertion angles based on clinical cone beam computed tomography data showed absolute deviations of 27° ± 18° to the corresponding postoperative measurements.ConclusionWith accuracy improvements of 80% to 90% in comparison with previously proposed approaches, the method is well suited for the use in individualized cochlear implantation.

Spline curve reconstructions appear to be the best option for anatomical diagnostics in clinical practice. Retrospective studies can be performed to further evaluate model-based evaluations.

Conclusions We have demonstrated that an automated insertion tool (a.k.a. robot) can be used to duplicate a complex surgical motion in inserting cochlear implant electrode arrays via the “advance-off-stylet” technique (AOS). As compared to human operators, the forces generated by the robot were slightly larger but the robot was more reliable (i.e. less force maxima). Objectives We present force data collected during cochlear implant electrode insertion by human operators and by an automated insertion tool (a.k.a. robot). Methods Using a three-dimensional, anatomically-correct, translucent model of the scala tympani chamber of the cochlea, cochlear implant electrodes were inserted either by one of three surgeons (26 insertions) or by the robotic insertion tool (8 insertions). Force was recorded using a load beam cell calibrated for expected forces of less than 0.1 Newtons. The insertions were also videotaped to allow correlation of force with depth of penetration into the cochlea and speed of insertion. Results Average insertion force by the surgeons was 0.004±0.001N and for the insertion tool 0.005±0.014N (p < 0.00001, Student’s t-test). While the average insertion force of the automated tool was larger than that of the surgeons, the surgeons did have intermittent peaks during the AOS component of the insertion (between 120° and 200°).