A clinical shift toward personalized cochlear implantation: Using preoperative planning to optimize insertion depth.

Objective To evaluate the clinical implementation of preoperative, anatomy-tailored planning for electrode selection in cochlear implantation, quantify planning accuracy under routine conditions, and identify factors associated with deviations from the planned angular insertion depth (AID).Methods We retrospectively analyzed 71 consecutive implantations; 17 cases were excluded due to unsuccessful segmentation/fusion, yielding 54 implanted ears. Before 2023 (Group A, n=32), electrode choice followed surgeon preference independent of cochlear duct length (CDL). From 2023 (Group B, n=22), automated OTOPLAN-based planning targeted an AID of 600° (cap 650°). Pre- and postoperative computed tomography scans provided cochlear metrics and postoperative AID. Planning accuracy was defined as the difference between planned and achieved AID. Linear models assessed demographic/clinical, anatomical, and surgical predictors. Speech outcomes at 6 months used Freiburger monosyllables at 65 dB HL.Results Group B showed deeper and more consistent insertions (median AID 568° [IQR 62°]) than Group A (527° [IQR 99°]; p<0.01). Median planning deviation was -9∘ (IQR 78°) with no relationship to planned depth ( R2=0.008, p=0.514). Greater inaccuracies were found in patients with shorter CDL (p=0.001) and in cases with observed intraoperative resistance (p<0.001).Conclusion cochlear anatomy exhibited substantial inter-individual variability. Implementing preoperative, anatomy-tailored planning was associated with the selection of longer arrays, deeper and more consistent AID, and overall high planning accuracy. Deviations from the planned position were primarily linked to shorter CDL and intraoperative resistance, whereas deeper targets themselves did not reduce accuracy. Audiological performance at 6 months did not differ significantly between groups, although a modest trend favored the planned cohort. These findings support the feasibility of routine, examiner-independent planning and suggest that patient-specific anatomical markers should inform the selection of an appropriate electrode array.