Instrument Tip Angular Kinematics - in the Search for New Metrics of Surgical Skill

Successful surgery requires performance of fine motor tasks with great precision. Understanding surgeons’ movement coordination may help to improve the control of surgical robots and to optimize the training of novice surgeons. Robot-assisted interventions allow for unobtrusive measurement of movement kinematics, and their wide use calls for the development of new objective metrics of surgical skill. To date, there was no extensive use of measures of angular motion to assess the skill of surgeons. We hypothesized that experienced robot-assisted surgeons change their hand orientation during critical tasks more than novices. We analyzed needle-driving movements of experienced robot-assisted surgeons and novices, and developed a novel metric of surgical skill: the normalized angular displacement. Using this metric, we found differences between experts and novices that were not captured by the classical metrics of path length and movement time.