Copyright © 2017 Otology & Neurotology, Inc. Unauthorized reproduction of this article is prohibited. Comparison of Experts and Residents Performing a Complex Procedure in a Temporal Bone Surgery Simulator  Ioanna Ioannou,  Yun Zhou,  Sudanthi Wijewickrema, yPatorn Piromchai,  Bridget Copson, zGregor Kennedy, and  Stephen O’Leary  Department of Surgery (Otolaryngology), University of Melbourne, East Melbourne, Victoria, Australia; yDepartment of Otorhinolaryngology, Faculty of Medicine, Khon Kaen University, Khon Kaen, Thailand; and zCentre for the Study of Higher Education, University of Melbourne, Parkville, Victoria, Australia Objective: To investigate the use of automated metrics from a virtual reality (VR) temporal bone surgery simulator to determine how the performance of experts and trainees differs when performing a complex otological procedure (mastoidectomy with posterior tympanotomy and cochleost- omy). Study Design: Cohort study. Methods: Using the University of Melbourne VR temporal bone surgery simulator, seven ENT consultants and seven ENT residents performed two trials of the surgical approach to cochlear implantation on a virtual temporal bone. Simu- lator recordings were used to calculate a range of automated metrics for each stage of the procedure, capturing efficiency, technique characteristics, drilled bone regions, and damage to vital anatomical structures. Results: Results confirm that experts drilled more efficiently than residents. Experts generally used larger burrs and applied higher forces, resulting in faster material removal. However, they exercised more caution when drilling close to anatomical structures. Residents opened the temporal bone more widely, but neglected important steps in obtaining a clear view toward the round window, such as thinning the external ear canal wall and skeletonizing the medial aspect of the facial nerve. Residents used higher magnification and reoriented the temporal bone more often than experts. Conclusion: VR simulation provides metrics that allow the objective analysis of surgical technique, and identification of differences between the performance of surgical resi- dents and their senior colleagues. The performance of residents could be improved with more guidance regarding how much force they should apply, what burr size they should use, how they should orient the bone, and for cochlear implant surgery guidance regarding anatomical regions requiring particular attention, to visualize the round window. Key Words: Cochleostomy—ENT— Expertise—Mastoidectomy—Performance—Simulation— Surgery—Technique—Training—Virtual reality. Otol Neurotol 38:xxx–xxx, 2017. Temporal bone surgery training typically follows the traditional apprenticeship model, whereby trainees prac- tice on cadavers under the supervision of expert instruc- tors (1,2). Recent years have observed increasing interest in simulation-based training as an alternative (3). Simu- lation can offer repeatable practice in a safe environment, exposure to a variety of surgical cases including complex and uncommon cases, and automated objective perform- ance evaluation (4). The latter relies upon an analysis of computer-generated metrics that are produced as virtual instruments interact with the anatomical model in the simulation environment. These data provide a rich stream of information on how instrumentation is handled, ‘‘tis- sue’’ handling, force applied by the surgeon to the surgical tools, surgical efficiency, and the preservation of anatomical structures. Exploration of these data pro- vides a detailed ‘‘history’’ of each operation across indices that have not readily been available before, and opens up new ways of studying the nature of expert surgical technique, and how this differs from the tech- nique exhibited by surgeons in training. Quantifying such differences provides an evidence base for identifying the competence level of a surgeon, and guiding surgical trainers to better educate their resident staff in operative surgery (5–7). A number of studies have evaluated the difference between expert and resident surgeons in simulator-gener- ated metrics of temporal bone surgery. Zirkle et al. (8) demonstrated that global measures such as number of hand movements, distance traveled, and time on task could be used to differentiate expert and novice surgeons; Address correspondence and reprint requests to Bridget Copson, M.B.B.S., University of Melbourne, East Melbourne, 3002, Australia; E-mail: bridgetcopson@gmail.com This work was funded by a grant from the Garnett Passe and Rodney Williams Memorial Foundation and a Linkage Project grant from Australian Research Council with Cochlear Ltd. as a partner. Presentation information: Not presented elsewhere. The authors disclose no conflicts of interest. DOI: 10.1097/MAO.0000000000001398 1 Otology & Neurotology 38:xx–xx ß 2017, Otology & Neurotology, Inc.