Seated vs. Standing Work Postures during Simulated Laparoscopic Procedures in terms of Muscle Loading, Comfort, and Performance.

Abstract

Work-related musculoskeletal disorders (MSD) have been a prevalent problem among surgeons. According to previous literature, back and shoulder muscles are the most affected body parts while performing surgeries. Poor work posture has been linked to the increase in MSDs among surgeons, and this is also prevalent in laparoscopic surgeries where surgeons tend to stand statically for long hours. Surgeries are performed mainly in standing postures and less commonly in seated postures. While the literature has investigated differences between both postures subjectively among surgeons, this paper aimed to investigate the difference using a combination of objective (muscle activity and performance) and subjective measures (the overall workload scale and localized musculoskeletal discomfort scale) during the performance of simulated laparoscopic procedures. Twenty 3rd and 4th year AUB medical students were recruited for this experiment. Four experimental tasks were examined on the LAPSIM, a laparoscopic surgery simulator, using two complexity levels (easy vs difficult) and two postures (sitting vs standing). Back (lumbar erector spinae) and shoulder (upper trapezii) muscle activities were recorded throughout the tasks using an electromyography (EMG) system. The performance of each participant from the LAPSIM output was analyzed (LAPSIM overall performance score and the time to complete tasks). Participants also subjectively assessed the experimental tasks using the overall workload scale and localized musculoskeletal discomfort scale. The collected data was analyzed using a two-factor repeated measures analysis of variance (ANOVA) to assess the effects of posture (sitting vs standing) and task condition (easy vs difficult) on EMG muscle activity, performance, and subjective ratings. The findings did not completely favor one work posture over the other. In comparison to seated, the standing posture resulted in significantly lower shoulder muscle activation in the easy and difficult tasks and lower completion times in the difficult tasks. On the other hand, based on participant feedback, sitting offered more stability, improved focus and precision, and the ability to work for longer periods; therefore, participants preferred the seated posture specifically for the difficult task. Furthermore, although differences were not statistically significant, sitting was associated with consistently lower averages in both the subjective and objective results of the low back. As so, alternating between both postures (e.g. between surgeries or within long surgeries) is recommended as it may decrease the health risks associated with each posture. Future studies may investigate other seat designs or a “hybrid” work posture, such as supported-standing, with respect to the traditional standing work posture.