The aim of our study was to evaluate results of insertion following cochlear implantation with Contour™ and Contour Advance™ electrode arrays in adult patients and to analyze individual insertion results for three experienced surgeons. We performed a retrospective analysis of postoperative 3D volume tomography results in 223 adult patients. The intracochlear electrode position was evaluated to be in scala tympani, scala vestibuli or with a dislocation from one scala to the other. Surgical methods were analyzed and assigned to the different surgeons. We observed a significant increase for scala tympani insertions from initially 33% to 84% and a reduction in dislocations from scala tympani to scala vestibuli from 71% with the Contour™ electrode to 22% with the Contour Advance™ electrode. Results for the different surgeons varied individually with regard to scala tympani insertion rates and dislocation rates over time. 3D Volume tomography offers an important method for postoperative quality control following cochlear implant surgery. The intracochlear electrode position could be determined in all cases. We were able to identify individual learning curves for insertion results. Controlling the insertion quality serves as a feedback of surgical results and may be helpful for improving surgical quality and thus rehabilitation results.