A New Force-Based Objective Assessment of Technical Skills in Endoscopic Sinus Surgery Toru Kumagai a,1 , Juli Yamashita a , Osamu Morikawa a and Kazunori Yokoyama b a National Institute of Advanced Industrial Science and Technology, Japan b Hana Clinic @ South Avenue, Japan Abstract. We propose objectively assessing endoscopic sinus surgery (ESS) skills by measuring the force applied to a patient model. We collected data on 16 sub- jects performing gauze packing task using a precise human nasal model with a six- degree-of-freedom force/torque sensor. Mann-Whitney’s U test was used to ana- lyze their performance. Intermediates (ESS: 10-50 cases) used significantly greater force than students or experts (ESS: over 150 cases) at the 5 % level. Maximum force improved only among experts. These results imply that young surgeons pay too little attention to force applied to patients or tissues. Keywords. Objective assessment, technical skill, endoscopic sinus sugery Introduction Objective assessment is one key to effective surgical technical skills training. Recent attempts to assess surgical skills have involved measuring the forces exerted during procedures using virtual reality [1] or by employing instrument-installed force sensors [2]. We are developing a training system for endoscopic sinus surgery (ESS). In this study we selected, as objective measures, maximum force (Fm) and average force (Fa) generated during instrument-to-patient contact, which we measured and evaluated during gauze packing (GP) into the ethmoidal sinus using a nasal model equipped with a force sensor (Figures 1 and 2). GP is the packing of gauze via the nasal cavity to ensure hemostasis or surface anesthesia, using forceps under endoscopic guidance. Appropriate packing pressure (PP) between the packed gauze and the lesion is necessary. The nasal mucosa 1 Corresponding Author: Senior Research Scientist, Institute of Advanced Industrial Science and Technol- ogy (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki 305-8566, Japan; E-mail: kumagai.toru@aist.go.jp. Figure 1. Bone unit of Nasal model. Figure 2. Experiment system.