Force perception threshold varies with experience in minimally invasive surgery

Indirect contact with the surgical environment using long laparoscopic instruments reduces haptic feedback in minimally invasive surgery. Furthermore, the friction force generated from the ports through which instruments are inserted into the body cavity masks the haptic information needed to perceive properties and structure of the tissue, complicating the control of the interaction forces between the instruments and tissue. It has been shown that friction forces inherent in the instrumentation increased the haptic perception threshold of naive subjects. A controlled experiment was conducted to examine the effects of surgical experience on force perception threshold in a simulated tissue-probing task. A mixed design was used, with friction, vision, and tissue softness as independent, within-subjects factors, and experience as a between-subjects factor. Applied force and detection time from fourteen participants (8 novices and 6 experienced surgeons) were recorded by a custom-built force-sensing system. Higher thresholds and longer detection times were observed when friction was present. Experienced surgeons applied greater force than novices, but were quicker to detect contact with tissue, suggesting that experience allowed surgeons to perform more efficiently while keeping within the limits of safety.