Background: Given the physical risks associated with performing laparoscopic surgery, ergonomics to date has focused on the primary minimally invasive surgeon. Similar studies have not extended to other operating room staff. Simulation of the assistant's role as camera holder and retractor during a Nissen fundoplication allowed investigation of the ergonomic risks involved in these tasks.
Methods: Seven subjects performed camera navigation and retraction tasks using a box trainer on an operating room table that simulated an adult patient in low lithotomy position. Each subject stood on force plates at the simulated patient's left side. A laparoscope was introduced through a port into the training box with four 2-cm circles as rear-panel targets located in relation to the assistant as distal superior, proximal superior, distal inferior, and proximal inferior target effects. The subjects held the camera with their left hand, pointing it at a target. The task was to match the target to a circle overlaid on the monitor. Simultaneously, a grasper in the right hand grasped and pulled a panel-attached band. A minute signal moved the subject to the next target. Each trial had three four-target repetitions (phase effect). The subjects performed two separate trials: one while holding the camera from the top and one while holding it from the bottom (grip effect). A 4 x 3 x 2 (target x phase x grip) repeated-measures design provided statistics. Dividing the left force-plate vertical ground reaction forces (VGRF) by the total VGRF from both plates provided a weight-loading ratio (WLR).
Results: The WLR significantly increased (p < 0.005) with proximal targets (2 by 80% and 4 by 79%). The WLR decreased 75%, 74%, and 71% over time. No difference existed between the grip strategies (grip effect, p > 0.5).
Conclusions: A high-risk ergonomic situation is created by the assistant's left or caudal leg disproportionately bearing 70-80% of body weight over time. A distance increase between the camera head location and the camera holder increases ergonomic risk. The phase effect was interpreted as a compensatory rebalancing to reduce ergonomic risk. Ergonomic solutions minimizing ergonomic risks associated with laparoscopic assistance should be considered.