Surgical robotics: impact of motion scaling on task performance

Robotic systems have been shown to enhance surgical dexterity, and the advantage has been hypothesized to result from the removal of tremor and addition of motion scaling. But these purported gains over traditional laparoscopic instrumentation have not been quantified. This study was designed to compare the surgical accuracy between conventional laparoscopic instruments and a robotic surgical system and evaluate the importance of tremor filtration (TF) and motion scaling (MS) in these robotic systems.

Fifteen participants with no previous surgical experience were enrolled. To simulate microsurgical techniques, a 29-gauge needle was used to puncture the center of 6 microscopic archery targets (circle diameters 0.5, 1.5, and 2.5 mm). The robotic system was configured to three different degrees of MS and compared with the unassisted laparoscopic platforms in accuracy.

Accuracy with robotic assistance with TF alone (1:1 MS) was not significantly different from unassisted laparoscopic control. Both moderate (2.5:1) and fine (7:1) MS significantly improved accuracy over traditional laparoscopic control (p < 0.001 for both). Robotic assistance with MS equalized the performance of both hands (p = 0.03) in precision, and manual laparoscopy demonstrated no statistical difference in handedness (p = 0.80).

Motion scaling, rather than tremor filtration, plays the major role in the enhanced accuracy seen in robotic surgical systems. Robotic assistance with MS significantly improved accuracy above laparoscopic instruments alone and robotic assistance with tremor filtration alone. MS also creates ambidexterity in an otherwise unidextrous population, optimizing the surgeon's ability to undertake tasks requiring microsurgical accuracy.