2013 Volume 2 Pages 11-16
The laparoscopic stapler is a surgical instrument that automatically creates visceral anastomosis. Although the laparoscopic stapler is widely used, objective ergonomic assessments are lacking. The purpose of this study was to quantitatively assess the force and muscle activities involved during the use of a laparoscopic stapler. The mechanical force needed to create anastomosis in a cattle colon was measured using a tensile tester. Three different loads (150N, 200N, and 250N) were applied individually to compare the anastomosis conditions. The force and muscle activities of the operators of the laparoscopic stapler were also examined. Eleven healthy female subjects (age, 27.4±10.7 years) participated in the study. Force and surface electromyography (EMG) of the flexor digitorum superficialis and flexor digitorum profundus muscles during the use of the laparoscopic stapler were measured and compared to each subject's maximum grip strength. Approximately 250N was necessary to operate the laparoscopic stapler appropriately. Although the mean grip strength of the subjects was 27.1±6.8kg, the mean force applied when they gripped the laparoscopic stapler was 15.1±4.1kg. Integrated EMG showed no differences between operating the laparoscopic stapler and gripping the hand dynamometer. This study demonstrated that the current design of laparoscopic stapler requires too much force to operate for individuals with small hands and/or low grip strength. In addition, the EMG results indicated that the enormous upper extremity muscular effort is not transmitted efficiently into power to operate the laparoscopic stapler, because of its handle design. Therefore, reconsidering the mechanism of the laparoscopic stapler is crucial to improve the usability of the laparoscopic stapler.