  Previous work on surgical skill assessment using intraoperative tool motion
in the operating room (OR) has focused on highly-structured surgical tasks such
as cholecystectomy. Further, these methods only considered generic motion
metrics such as time and number of movements, which are of limited instructive
value. In this paper, we developed and evaluated an automated approach to the
surgical skill assessment of nasal septoplasty in the OR. The obstructed field
of view and highly unstructured nature of septoplasty precludes trainees from
efficiently learning the procedure. We propose a descriptive structure of
septoplasty consisting of two types of activity: (1) brushing activity directed
away from the septum plane characterizing the consistency of the surgeon's
wrist motion and (2) activity along the septal plane characterizing the
surgeon's coverage pattern. We derived features related to these two activity
types that classify a surgeon's level of training with an average accuracy of
about 72%. The features we developed provide surgeons with personalized,
actionable feedback regarding their tool motion.
