by Caroline von Fluegge-Chen
It is a fact of life that job and career can be stressful. But some occupations also take a physical toll: persistent aching, throbbing or tingling in the hand, wrist, elbow, shoulder or neck.
These insidious soft-tissue ailments — variously known as repetitive strain injuries, cumulative trauma disorders or work-related musculoskeletal disorders — include the debilitating nerve injury of carpal tunnel syndrome and the inflamed tendons of tendinitis. They not only can cripple a person’s ability to earn a living. They may also make it difficult even to twist the lid off a jar, wash the dishes or turn the steering wheel.
Therapies like steroid injections, pain relievers or surgery can go a long way in alleviating pain. But treatments do not always offer a definitive cure, and injuries can recur. Prevention is therefore paramount.
To reduce the risk of injury, many workplaces, with help from researchers, have adopted ergonomic interventions: measures that tailor equipment or job routines to accommodate the human body. But while real-world success stories abound, scientists are still sorting through the evidence to determine which ergonomic measures really work.
Each year, more than 100,000 new cases of upper-extremity ailments are reported to the Occupational Safety and Health Administration. Problems are especially common among those who do heavy or frequent manual handling and lifting tasks, whether in manufacturing, construction, meatpacking or nursing care.
But repetitive strain injuries are perhaps most infamously associated with computer use. Widespread media coverage in the late 1980s and early ’90s described an emerging plague of wrist pain from carpal tunnel syndrome in computer keyboard operators, writers and other office workers.
Skepticism arose over whether tapping on a keyboard, or other more forceful repetitive motions, could result in so much discomfort and disability. In the years since, researchers have established that exerting the hands, arms or shoulders in tasks that require high levels of force, many repetitions, awkward postures or high amounts of vibration increases the risk of musculoskeletal disorders.
But research in the last decade has established that carpal tunnel syndrome is “not as common in computer users as people have believed — in the absence of good evidence — that it was,” said Dr. Fredric E. Gerr, an occupational medicine physician and ergonomics investigator at the University of Iowa in Iowa City. And whether typing actually causes that disorder remains controversial, with some recent studies calling into question any significant connection.
Nonetheless, he added, “The epidemiological evidence is overwhelming that the more people type, the more pain they have.”
Neck and shoulder pain is the most common upper-extremity musculoskeletal problem among computer users. In a 2002 study tracking 632 computer users newly hired at major Atlanta companies, Dr. Gerr and colleagues observed that roughly 60 percent developed neck or shoulder pain in the first year, though the study did not track how long symptoms persisted. About 40 percent reported hand or arm symptoms, mostly from tendinitis. Only 1 percent developed carpal tunnel syndrome.
Younger generations growing up in the digital age are likewise joining the ranks of the typing wounded. Surveys at two universities found that 40 to 50 percent of undergraduates experience upper-extremity pain from using their computers. Colleges do not build dormitory furniture to be ergonomically adjustable, said Dr. Benjamin Amick, scientific director of the Institute for Work and Health in Toronto, who was a co-author of those studies. “They build it to be indestructible.”
In the business sector, many companies have made significant ergonomic improvements to the work environment, particularly in office and manufacturing settings, experts said. The idea is to minimize the stresses on hands, arms and shoulders.
For instance, in offices since the ’90s, thick keyboards with stiff keys have given way to thinner, softer-touch versions. More attention is also paid to proper positioning of the keyboard, monitor and chair and to alternative types of computer mice. And in some automobile manufacturing plants, companies have modified assembly-line equipment to take some of the physical load off workers, along with making changes to rotate employees along the line.
Employers are “recognizing that you need variety in the motions that you do, rather than constantly using the same exact muscles and nerves and tendons,” said Barbara Silverstein, research director at the Safety and Health Assessment and Research for Prevention program of the Washington State labor department.
Such changes often pay off. In a soon-to-be published analysis of data from more than 5,000 Washington companies surveyed in 1998, 2001 and 2003, Dr. Silverstein found that businesses that reported implementing ergonomic measures also saw a decrease in musculoskeletal injuries and absenteeism rates.
In addition, according to the federal Bureau of Labor Statistics, the number of repetitive strain cases per 10,000 full-time workers dropped from a high of 41 in 1994 to 24 in 2001. (The agency has stopped tracking data in this category of “repeated trauma” disorders.) However, some researchers say that the data is unreliable and undercounts all occupational injuries and illnesses, because of problems with underreporting and with changes in recordkeeping requirements.
Meanwhile, scientists are seeking to build a base of rigorous evidence for ergonomic prevention strategies to convince skeptics of their value. But so far, reviews of the research have turned up limited or conflicting proof of positive benefits from such measures as stretching exercises or various workstation adjustments for computer users.
A major difficulty is that although many studies have demonstrated ergonomic measures to be helpful, few have been the kind of large, high-quality randomized controlled trials that provide clear-cut answers, said Dr. David Rempel, an ergonomics researcher at the University of California, Berkeley. Such trials are costly and complex to design well for workplace settings, he explained, and federal financing for workplace safety studies is scarce.
“A lot of us are banging our heads against that wall now,” Dr. Gerr said of the challenge of ascertaining which interventions work.. In the absence of definitive evidence, clinicians continue to exercise their best judgment in finding good solutions for their patients.
By INGFEI CHEN, NYT