Physical workload in surgery : from risk assessments to interventions

Sammanfattning: Surgeons often suffer from work-related musculoskeletal disorders (WMSDs), with the neck, shoulders, and low back being the most affected body sites. Among other factors, the high physical workload has been recognized as a major risk factor contributing to the high occurrence of WMSDs. Surgical modalities are evolving from open to minimally invasive surgery, such as laparoscopic and robot-assisted surgery; postural loads in the neck have been shown to decrease along with this transition. However, the prevalence of pain in the neck/shoulder in minimally invasive surgery has been reported controversially higher than that in open surgery. Additionally, as healthcare systems are rationalized, work intensification has drawn attention in many health-related occupations. Task-based analyses may offer details about the workload levels in different tasks in an occupation, but such studies have rarely been carried out for surgeons. Study I applied task-based analyses to investigate muscular and postural loads of surgeons in open neck surgery and compared the workload to that in nonsurgical tasks and robot-assisted surgery. The results showed that, during surgeries, the head forward bending and shoulder muscle activity was alarmingly high and significantly higher than that in nonsurgical tasks and robot-assisted surgery. Increasing time in surgical cases, which is in line with the aim of rationalizations, would inevitably result in worsening physical stress in the neck for surgeons unless preventive measures are taken into consideration. Laparoscopic surgery often uses a two-dimensional (2D) laparoscopic vision system (LVS) to deliver the image of an operation site to the surgeon. Three-dimensional (3D) LVSs that can offer stereoscopic visual perception have been shown to improve surgical performance. However, traditional 3D LVSs require shutter glasses; surgeons have complained about poor image quality and have experienced visual discomforts when using them. Novel 3D LVSs without shutter glasses have been shown in lab-based studies to provide users with better image quality and less visual discomfort. However, previous studies did not test those novel 3D vision systems in a surgical scenario; those that tested the new systems did not find consistent results. Study II chose a crossover study design and compared the visual quality, discomfort, and surgical performance of 18 medical students who performed four simulated laparoscopic tasks with the two 3D LVSs (with and without shutter glasses). Overall, Study II found similar preferences in both systems and no significant difference in surgical performance between the two systems. However, the spatial orientation and sense of depth of the conventional 3D LVS with shutter glasses were significantly but minorly better without glasses. Kinematics, such as postures and movements, is essential in assessing physical workload among occupations. Traditionally, kinematics is commonly measured by accelerometer-based (acc) methods, which have been demonstrated in lab-based studies to induce significant errors when velocities are high. Inertial measurement units (IMUs), e.g., combining accelerometers and gyroscopes (acc+gyro) to overcome acceleration-related errors, have been shown to improve the accuracy of kinematic measurements. When measuring arm movements, two different angular velocities have been used, inclinational velocity and generalized velocity, which have been shown to be significantly different from each other in lab studies. However, no previous studies have compared results between these sensor and velocity types in field measurements. Study III measured postures and movements of the arm and trunk of warehouse workers using both sensor types, acc and acc+gyro, and calculated corresponding angles and velocities. For the arm, Study III further calculated both inclinational and generalized velocities. As a result, Study III showed significant differences in the velocities calculated by different sensor types, i.e., acc and acc+gyro, and calculated using different velocity types, and found significant but minor differences in angles between acc and acc+gyro methods. The generalized arm velocity measured with acc was about four times higher than the inclination velocity from acc+gyro. In conclusion, Study III showed that it is erroneous to directly compare velocities from different studies using different sensor- or velocity types. In light of the results and equipped with the methodological knowledge from Study I-III, Study IV investigated the effects of prismatic loupes on surgical workload and performance. Prismatic loupes can alter the incoming light path and may improve head postures and reduce neck discomfort. Few studies with quality measurements have tested prismatic loupes among surgeons. Study IV compared the kinematics, muscular loads, surgical performance, and discomforts of surgeons in three simulated surgical tasks with their own, non-prismatic loupes (own), a pair of low-tilt prismatic loupes (LT), and a pair of high-tilt prismatic loupes (HT). Overall, prismatic loupes significantly reduced the cervical muscular load and improved the head posture without increasing surgical errors. However, HT loupes increased task completion time. Open questions further revealed the motives behind the overall preference for LT prismatic loupes. In conclusion, open surgeons endure awkward head postures and high muscular loads in the shoulders, which are much higher than that in nonsurgical tasks and robot-assisted surgery. Therefore, interventions are needed to prevent work intensification in the progress of rationalization. Prismatic loupes may reduce cervical loads for certain open surgeons; however, new studies are required to investigate the long-term effects of prismatic loupes on surgeons. Overall, each step should be carefully examined in transitioning from conventional to new surgical modalities; challenge-driven approaches are a great tool for navigating research in complex and interdisciplinary domains.