Control of laparoscopic instrument motion in an inanimate bench model: implications for the training and the evaluation of technical skills

Computer-assisted analysis of wrist movement has recently emerged as an objective laparoscopic performance evaluation method. The first purpose of this study was to assess the differences in motion characteristics between the tip of the instrument and the wrist. The second purpose was to describe the control strategies used to move laparoscopic instruments. During a bead transfer task, motions of a laparoscopic needle driver's tip, heel, and the participants' wrist were monitored. Results showed that large amplitude movements were best described by movements of the wrist, and small amplitude movements were evidenced by motions of the instrument tip. Thus, for describing expertise, and for evaluation and feedback, motion of the tip of the laparoscopic instrument should be quantified, in addition to motion of the wrist. The motions of the instrument were controlled by utilizing the flexibility of the skin of the laparoscopic trainer in addition to using the fulcrum, and sliding through the trocar. In order to increase fidelity, virtual reality trainers should simulate the flexibility of the real structures around the insertion of the instrument.