WHAT WE DO...AND WHOM WE SERVE:
The pager-sized device can record a day's worth of postural data.
Repetitive Stress Injuries
PREVENTING THE INJURY
Most backaches are cumulative—the result of thousands of movements that add up to overuse and strain. Old diagnostic tools made it hard—or expensive-—to identify which movements pushed the back beyond its limits.
In the past, the continuous assessment of physical exposures was too costly and too time consuming, said Peter Johnson, PhD, whose ergonomics lab specializes in measuring occupationally related physical exposures. With advances in technology, “a new age in musculoskeletal exposure assessment is developing,” he said.
Observation, even by a trained ergonomist, misses many of the body’s clues, especially isolated, infrequent events. Other methods, such as muscle electromyography (EMG) and lumbar motion monitors, can be invasive and can cost up to $20,000. Johnson sought to develop a simple and relatively inexpensive device to measure a worker’s posture and torso movements over the course of a work shift.
Tree thinners work from a mobile platform.
Johnson helped develop the Virtual Corset™, a new research tool to better understand and ultimately reduce work-related musculoskeletal disorders. The pager-sized unit, strapped to a worker’s back, arms, or chest, can collect a continuous record of the worker’s changing posture.
He worked with Vermont-based Microstrain, Inc., to develop a system that can cost less than $1,000 and be small and sturdy enough to be used in the field. Its two megabytes of memory can collect a day’s worth of data, opening up new avenues for ambulatory exposure assessment. This can help researchers better understand the relationship between cumulative postural exposures, load patterns, and musculo-skeletal disorders.
Johnson’s team developed the device for our department’s Pacific Northwest Agricultural Safety and Health center as part of a project to create tools to measure physical exposures during agricultural and forestry work. In cooperation with the Field Research and Consultation Group, the team wants to use the Virtual Corset™ to compare two tree fruit harvesting methods-, using the traditional ladder and using mobile platforms.
Mobile platforms are four-wheel, self-guided, all-terrain vehicles that move slowly down a row of fruit trees and carry up to eight workers. The Washington tree fruit industry is experimenting with them as a way to improve harvest productivity and fruit quality, while reducing ladder-related injuries. An unknown is how the mobile platforms will affect the physical loads on the upper arms, shoulders, and back.
Lifting devices can help reduce strain.
Also, a team from the University of British Columbia is using the Virtual Corset™ in a study of low back strain in five heavy industries.
PREDICTING THE DISABILITY
Back and neck sprains aren’t the most serious workplace injuries, but they are the most costly, as revealed by a measurement system developed by the Occupational Epidemiology and Health Outcomes Program.
When calculated by time lost from the job, measured in “years of productivity lost” (YPL), back and neck strains yield a value more than five times higher than any other category of injury.
Back sprains, along with carpal tunnel syndrome—a repetitive strain wrist disorder—are among the less severe, nonhospitalized injuries that account for most of the disability costs in the workers’ compensation system.
Ergonomic keyboards.
Gary Franklin, MD, MPH, research professor, director of the UW Occupational Epidemiology program, and medical director of the state Department of Labor and Industries, wants to find out how such relatively minor injuries can cause major disability. His team is in the fourth year of a five-year grant from the National Institute for Occupational Safety and Health (NIOSH) to identify risk factors so workers can be helped before they become disabled.
“This is the biggest prospective study ever done on injured workers in the country,” Franklin said, calling it the “Framingham study of workers’ compensation” in comparison with the landmark epidemiological study on cardiovascular disease begun half a century ago.
Back injuries and carpal tunnel syndrome are the “two giant issues in workers’ comp,” he said. “Whoever figures these two out has the cure for the comp system.”
His population-based study is looking for the factors that predict chronic disability. Although most injured workers return quickly to work, a substantial number do not. Franklin’s team is developing an early warning system to identify workers most at risk for chronic disability. Those workers can be targeted for early support and intervention with a goal of returning them to work. “We can try to predict which workers are more likely to become disabled,” Franklin said, “then we can deliver care differently.”
FURTHER READING
Turner JA, Franklin G, Fulton-Kehoe D, Egan K, Wickizer TM, Lymp JF, Sheppard L, Kaufman JD. Prediction of chronic disability in work-related musculoskeletal disorders: a prospective, population-based study. BMC Musculoskelet Disord 2004; 24(5):14.