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Assessing Posture in Surgery: Video Sampling of Microsurgery
Abstract
Prolonged static work postures and posture constraints imposed by surgical equipment may increase the risk of musculoskeletal pain and discomfort in surgeons. Four surgeons were video recorded performing live microsurgery and a work sampling methodology was used to quantify their upper body postures, investigating the proportion of static and dynamic postures, and compare surgeon postures to the postures found in laboratory studies. Surgeons were found assuming flexed postures in their neck, shoulder, elbow, and back. Most of the procedure consists of static postures where movement greater than 10 degrees per second was not frequently detected in our sampling. Of the four surgeons, one surgeon was found on average to have lower neck flexion than the other three. Further investigation showed the surgeon looking through the microscope at a distance to assume a more upright neutral posture. Identifying surgeon work postures is a key step to understanding how to reduce musculoskeletal pain and discomfort.
... Posture-matching was conducted using University of Michigan's 3D Static Strength Prediction Program (3DSSPP, version 6.06) as shown in Fig. 2. Although posturematching accuracy may be limited by anthropometric scaling and inverse kinematic algorithms, published strategies for improving posture-matching accuracy were applied for each pull exertion (Beck and Chaffin, 1992;Vi et al., 2000;Liu et al., 1997;Yu et al., 2012). For each photo, the following steps were completed: ...
... (1) Input participant's anthropometry (i.e., gender, height, and body weight) and observed horizontal and vertical pulling force in 3DSSPP (2) Execute 3DSSPP's posture prediction module using inverse kinematics (Beck and Chaffin, 1992) based on known handle heights (3) Refine posture prediction manually by uploading the 2D photo captured for the specific pull exertion in 3DSSPP (Vi et al., 2000), and then scale and rotate the digital human model to match camera distance and participant's position as seen in the photo (4) Input measurable sagittal angles into 3DSSPP, i.e., lower arm, upper arm, upper leg, lower leg, and trunk. Sagittal angles are estimated from 2D photos by marking the pixel location of joint centers and computing the angle formed by these points using MathWorks' Matlab™ software R2012a (Yu et al., 2012), and (5) Adjust and refine the remaining angles using 3DSSPP posture input interface to match 2D photo (Liu et al., 1997) and satisfy biomechanical constraints, e.g., known handle height and center of pressure is within base-of-support. ...
Manual exertions with one hand are commonly performed; however, current one-handed normative strength databases note large strength variations not explained by participant demographics, e.g., age and gender. This study models how the postures that participants choose impact their one-handed pull strength. Lower-extremity posture, defined as distance from handle, were measured for 31 participants performing two maximum one-handed frontal pull exertions at three handle heights, resulting in a strength-posture dataset of 186 maximal exertions. Regression models with anthropometric and lower extremity positions were created for each handle height. Smaller distances between the front-foot and handle were associated with higher strength. Larger back-foot distance to handle was positively associated with strength for low and waist-level handle heights. Larger hip distances from the handle increased pull strengths and interacted with feet positions. This study quantifies the relationship between one-handed pull strength with anthropometry and postures and provides practitioners posture-based equations that can be used to estimate safe pull strengths given workplace posture constraints.
Relevance to industry
Maximum one-handed pull strength models are presented that can assist practitioners in: 1) assessing whether strength demands are within worker's capability in the workplace, 2) designing workplaces that better accommodate the range of postures chosen during maximum exertion, and 3) identify workplace layout constraints that adversely impact strength capabilities.
... Surgical staff posture is very diversified depending of type of the surgery, available medical facilities and several other influential factors. Yu et al. [24] conducted a field observation study to quantify surgeon postures and they showed that posture adjustments occur frequently during ongoing surgeries. ...
Airborne particles released from surgical team members are major sources of surgical site infections. To reduce the risk of such infections, ultraclean-zoned ventilation systems have been widely applied, as a complement to the ventilation of the main operating theatre. The function of ventilation in an operating theatre is usually determined without considering the influence of the staff members' posture and movements. The question of whether the surgeon's posture during an on-going operation will influence particle distribution within the surgical area has not yet been explored in depth or well documented.
Operating room ventilation is quite important to protect patients from infection risk inside a surgical field. The laminar flow units (LAF) used in these applications contribute to removal of pathogen particles from the operation area by creating a protection zone on the surgical field. In this study, effect of LAF diffuse size on airflow and particle distribution in an operating room is investigated using computational fluid dynamics (CFD). Three different diffuser sizes (1.8 m x 2.4 m, 2.4 m x 2.4 m, 3.2 m x 3.2 m) and three different particle diameters (5 µm, 10 µm, 20 µm) are examined. In the modeling of airflow and particle motion, the Realizable k-ε turbulence model and Lagrangian approach are used, respectively. The distributions of airflow and particles originated from the surgical team are analysed. Also, the air change efficiency is predicted as for the entire operating room and for the breathing zone. The results reveal that the LAF diffuser size has a decisive role in air velocity and contaminant distribution in the operating room. It is seen that the amount of particles deposited on the operating table could be reduced up to 73% by increasing the diffuser size.
Physical discomfort has been frequently reported in surgery, and previous studies have focused on surgeon postures and posture movements. The aim of this study is to develop a methodology and collect pilot data that can be used to test the hypothesis that static work requirements during microsurgery exceed published endurance capabilities and are a source of surgeon fatigue. Eight microsurgery surgeons were analyzed for this study. An event-based time study was performed for the entire duration of the microsurgery. Posture was quantified using ten frames randomly sampled from two surgeons using 3D Static Strength Prediction Program, and outputs were used to calculate endurance limits and maximal acceptable effort. Results found that 83% of microsurgery is performed with the microscope. Posture adjustments were highest during rest (5.5 adjustments per minute) and lowest during microscope task (0.3 adjustments per minute). Back and shoulder postures deviated further from neutral during microscope task than rest. The % MVC in the shoulders and torso have endurance times of 5-57 minutes and exceeded maximum acceptable efforts. Results suggest that the operating microscope constrains surgeon posture and restricts posture adjustments. Microsurgery is predominantly microscope tasks, and endurance capabilities are a concern for surgeon fatigue. Application of current tools to surgery are limited due to the low-force and non-cyclical nature of surgical work; however, these findings can be used to design future studies testing larger surgeon populations and workplace improvements.
The widely held belief that laparoscopy causes greater strain on surgeons' bodies than open surgery is not well documented in scope or magnitude. In the largest North American survey to date, we investigated the association of demographics, ergonomics, and environment and equipment with physical symptoms reported by laparoscopic surgeons.
There were 317 surgeons identified as involved in laparoscopic practices who completed the online survey. Data collected from this comprehensive 23-question survey were analyzed using chi-square.
There were 272 laparoscopic surgeons (86.9%) who reported physical symptoms or discomfort. The strongest predictor of symptoms was high case volume, with the surprising exceptions of eye and back symptoms, which were consistently reported even with low case volumes. High rates of neck, hand, and lower extremity symptoms correlated with fellowship training, which is strongly associated with high case volume. Surprisingly, symptoms were little related to age, height, or practice length. The level of surgeons' awareness of ergonomic guidelines proved to be somewhere between slightly and somewhat aware. A substantial number of respondents requested improvements in regard to both the positioning and resolution of the monitor.
Far beyond previous reports of 20% to 30% incidence of occupational injury, we present evidence that 87% of surgeons who regularly perform minimally invasive surgery suffer such symptoms or injuries, primarily high case load-associated. Additional data accrual and analysis are necessary, as laparoscopic procedures become more prevalent, for improvement of surgeon-patient and surgeon-technology interfaces to reverse this trend and halt the epidemic before it is upon us.
Sustained joint load in extreme positions (namely maximally flexed or extended positions) has been described as causing pain. The aim of the present study is to analyse eight different sitting work postures with respect to extreme positions, and to assess the mechanical load and the levels of muscular activity arising in defined extreme positions of the cervical spine. Ten healthy female workers from an electronics plant took part in laboratory experiments. For seven of these, levels of neck and shoulder muscular activity in sitting postures with the cervical spine in different manually-adjusted extreme positions were recorded using surface electrodes. Loading moments of force about the bilateral motion axis of the atlanto-occipital joint (Occ-C1) and the spinal cervico-thoractc motion segments (C7-T1) were calculated. Extreme or almost extreme positions occurred in sitting postures with the thoracolumbar back inclined slightly backwards or with the whole spine flexed. Electromyographic (EMG) activity levels were very low in the manually-adjusted extreme positions. The load moment for the Occ-Cl joint when the whole neck was flexed was only 1·2 times the value for the neutral position of the head, but for C7-T1 it increased to 3·6 times. It is concluded that extreme positions of the cervical spine do occur in sitting work postures, and that the levels of muscular activity in such positions are low. Thus, recordings of muscle activity and calculations of load moment alone are not a sufficient basis for evaluating work postures: thorough recordings of spine positions should be included.