Ergonomic aspects of four different types of laparoscopic instrument handles with respect to elbow angle

Abstracts

Background: Only few studies have tested different ergonomic aspects of the working posture assumed by laparoscopic surgeons. Although no experimental data are available for a laparoscopic setting, a working posture with a horizontal forearm or an elbow angle 90° to 120° has been recommended for performing minimally invasive surgery (MIS). The comparison of electromyogram (EMG) activities in different muscles provides information about the force developed by each muscle and allows assessment of its contribution to a functional movement. The current study aimed to investigate whether certain handles do not support this posture. Methods: For this study, 12 volunteers were postured in two different standardized arm positions, defined by elbow angles of 90° and 120°. They were manipulating a 0.1-N and a 2.5-N microswitch with four different types of instrument handle design: axial handle, ring handle, shank handle, Hirschberg handle. During the test, the EMG activities of five forearm muscles were recorded and normalized with respect to the maximum voluntary activity of the respective muscle. Results: Virtually no significant difference in EMG activity was found between the two elbow angles in any of five forearm muscles for a simple gras** maneuver. Thus, the muscle activity required to manipulate different types of MIS handles is similar for the elbow angles of 120° and 90°. Conclusions: The current study did not show relevant differences between the two elbow angles for any of the four handles during a simple gras** maneuver with respect to the force required in the main forearm muscles.