In recent years, hundreds of thousands of otherwise healthy computer users have developed a painful, debilitating and sometimes disabling condition known as repetitive strain injury (RSI). Although the exact causes of RSI are imperfectly understood, the disorder is clearly associated with overusing computer keyboards, mice and other input devices. Repetitive strain injuries now account for more than half of all work-related illnesses, a nine-fold increase since the early 1980s. Recent studies by industry and occupational health physicians suggest that 20% to 25% of computer users, both vocational and recreational, have symptoms related to their computer activities.
In the adaptive technology field, the computer is regarded almost universally as an empowering technology. Regrettably, the enabling "power" of the computer does not and cannot immunize against overuse injuries. The link between computer use by persons with disabilities and RSIs is not a matter for speculation. In my work as an adaptive technologies/workplace accommodation consultant, I have met several individuals who report symptoms of or who have been diagnosed with an RSI. The effects of chronic RSI — constant pain, desensitized fingers, or loss of the use of the hands — could devastate the life of a person with a disability. It is ironic that using an empowering technology might precipitate another disability.
In this paper I highlight my findings, based on a literature review and three case-studies, on repetitive strain injuries as they pertain to persons with disabilities. I begin, in Part 1, by providing background information about repetitive strain injuries. In Part 2 I discuss why persons with disabilities who use computer-based assistive devices are susceptible to overuse injuries. I conclude, in Part 3, by outlining the elements of a comprehensive program of RSI prevention for persons with disabilities.
A repetitive strain injury refers to damage to the muscles, tendons, ligaments, blood vessels, nerves and other soft tissue. The effects of the disorder are cumulative; they develop after months or years of repetitive, stressful, or awkward movements that gradually wear down the musculoskeletal system. The onset occurs so slowly that the activities that cause the injury may go unnoticed until the damage is irreparable.
RSIs encompass a broad range of disorders affecting different parts of the body. Of the RSIs associated with computer work, carpal tunnel syndrome is the most widely publicized, but is actually rarer than tendon-related disorders (tendinitis, tenosynovitis, DeQuervain's disease), thoracic outlet syndrome, epicondylitis (tennis elbow) and ganglion cysts.
RSIs are also known as repetitive motion injuries (RMI), musculoskeletal injuries (MSI), occupational overuse syndrome (OOS), cumulative trauma disorders (CTD) and work-related upper limb disorders (WRULD).
Almost any part of the body can be affected, but in computer users, injuries usually occur in the fingers, hands, wrists, forearms, elbows, upper arms, shoulders, neck, or back. An individual may experience symptoms in one area or many.
Symptoms include soreness, aching, throbbing, tightness, coldness or burning, numbness or hypersensitivity, weakness, shooting pains, tingling, stinging and night pains. Symptoms may present alone or in combination.
Any activity that involves prolonged and persistent movement can lead to an RSI, including lifting, carrying, typing at a computer keyboard, operating a mouse or a trackball, using certain tools, or working on an assembly line. Practising a musical instrument or playing certain sports can also precipitate an RSI.
Yes. Sensible job design, proper workplace layout and good work practices minimize the risk of developing repetitive strain injuries.
Using adaptive technologies exposes persons with disabilities to the risks of RSIs. In this section I review the risk factors that are thought to lead to RSIs as they pertain to persons with disabilities who use computer-based compensatory devices.
An RSI occurs when tissue is subjected to thousands of repetitive motions. According to one theory, the movements cause microscopic tears in muscles, tendons and ligaments. The tearing leads to inflammation, and the debris left by inflammation forms scar tissue that binds muscles and stiffens tendons. The injured tissue contracts, decreasing its range of motion. Tendons normally glide smoothly inside lubricated sheaths. If the tendons are damaged, the lubricating fluid dries out, causing tendon and sheath to adhere and chafe. Unless the cycle of injury is interrupted, the tissue fails to recover fully, and a long-term, chronic problem results.
Persons with disabilities who rely on computers for writing, reading, or communicating (e.g., screen reader and TDD users) are obvious candidates for repetitive strain injuries. Persons who operate their computers with other parts of their bodies may develop overuse injuries in those parts: in the neck and shoulders (for head- and mouth-stick users) or the hip and leg (for toe-typists). The exaggerated lateral head motions used by some persons with low-vision to read an extra-large monitor can lead to neck problems.
Good posture is the ability to maintain proper alignment of the bones and length of the muscles. If the bones are out of alignment, the muscles must strain to hold the body in position. Good posture is dynamic, not static. The human body must move to remain healthy. Static loading — holding parts of the body immobile for long periods — tires the muscles. Fidgeting, changing positions, and moving around help to reduce the postural fatigue associated with computer work.
Unhealthy working posture is a primary risk factor in RSI. For computer users, the muscles of the shoulders, neck, and arms are particularly susceptible to biomechanical stresses due to incorrect posture. Poor posture may be responsible for, or exacerbate, nerve compression or entrapment in the neck or upper body, as in cases of thoracic outlet syndrome.
Postural habits are influenced by a person's genetic heritage and functional limitations. These factors affect, for example, one's range of motion; flexibility; strength; balance; muscle bulk; sensitivity to pain; and susceptibility to certain illnesses. If due to a pre-existing injury or condition, a person has partial or no use of a body part, she or he may unconsciously compensate by adapting an awkward working posture.
A properly configured computer workstation promotes good sitting posture and allows the user to work in greater comfort for longer periods. A workstation consists of a desk and/or computer table and a chair, plus the equipment the person needs to do their work — keyboard, monitor, CPU, printer, telephone, filing cabinets, storage shelves and so on. In addition, environmental factors — lighting, temperature, air quality and noise - affect workstation comfort and safety.
Postural habits are shaped by the individual's workstation setup. The workstation should adapt to the requirements of the human body, not vice versa. The standard computer keyboard impairs good posture; its design virtually enforces cramped fingers, ulnar deviated wrists, pronated forearms, winged elbows and stooped shoulders. When workstation components are inappropriately chosen or incorrectly positioned, the body learns, in effect, to feel most comfortable in a biomechanically hazardous working posture. A person with low-vision, for example, whose monitor is too small or too far away from the eyes, may habituate to craning the neck.
A wheelchair designed for mobility may be unsuitable for computer work. The chair may provide insufficient back support or lack adjustability. If the wheelchair cannot easily be readjusted, finding a biomechanically safe typing position may prove impossible.
To minimize the risks of RSIs in persons with disabilities, a workstation must be selected and set up with care. Setting up a workstation requires as much attention as configuring the software and hardware. Some agencies that purchase assistive technologies on behalf of persons with disabilities allocate funds for computer equipment, not workstations. Technicians who set up workstations for persons with disabilities may have little understanding of human factors and ergonomics.
Operating an assistive device from a so-called "ergonomic" workstation will not, in itself, inoculate against RSIs. An expensive ergonomic chair, for example, does not automatically correct poor posture; an adjustable chair only encourages better posture. If the person slouches, never adjusts the chair, or rarely takes breaks from typing, the chair contributes little or nothing to their safety.
Most computer users can benefit from learning healthier work practices, such as sitting properly, varying one's working style (e.g., writing with pens and paper, performing some tasks standing up); taking regular keyboard breaks; resting the eyes; keeping the monitor screen free of dust, glare and shadows; and practising safer keyboard and/or mouse technique. Safe work habits are skills that an individual must cultivate. "Ergonomic" equipment complements, but does not replace, healthy work habits.
Taking regular breaks from the keyboard gives the body time to recuperate from the biomechanical strains of computer work. It is generally recommended that computer users get up from their workstation for ten minutes once an hour; stand up and stretch two or three times every hour; and pause to rest the hands and arms for five seconds every few minutes.
For persons for whom the computer is the primary means of communicating, the temptation to spend long hours at the keyboard is understandable. However, working this way over months or years creates the conditions for overuse injuries to occur.
Many persons with disabilities have had no opportunities to learn proper keyboard and mousing techniques. The need for proper training is all the more critical for persons whose functional limitations constrain their working style. It is almost always possible to better one's technique through training and workstation modifications.
Operating a computer is a physically demanding task. Typing gives the arms and hands a strenuous workout, and the muscular effort required to sit, even in good postures, eventually tires the body. (Sitting in an awkward posture wearies the body quicker.)
A fit body is less likely to develop an RSI. Overall flexibility and upper-body strength prepare the body for the rigours of computer work. Stretching keeps muscles and tendons supple; tight muscles work less efficiently. Regular, vigorous exercise improves blood circulation. Good circulation safeguards against RSI in two ways: the soft tissue more readily absorbs nutrients from the blood; and the blood more easily flushes away metabolic wastes. When circulation is impaired, metabolic byproducts accumulate with consequent poorer functioning of muscles and tendons.
While persons with disabilities are as interested in health and fitness as the general population, opportunities to participate in fitness programs are limited.
Other activities involving the hands and upper body can contribute to the development of RSIs: navigating by cane or guide dog; signing; wheeling one's wheelchair; driving a car; operating a home computer; playing video games; weightlifting; playing certain sports; practising a musical instrument; cooking; gardening; needlepoint; and carpentry.
Stress is thought to be a primary risk factor for RSI. Many persons with disabilities live with a great deal of stress. Discrimination, unemployment, underemployment, job insecurity, fast-paced workplaces, deadline pressures, expectations to "keep up" with able-bodied colleagues, and the drive for greater productivity heighten the anxiety level experienced by persons with disabilities.
With the support of the Ontario Ministry of Labour, I propose to develop, in collaboration with disabled employees in the Ontario Public Service, a repetitive strain injury prevention program tailored for persons with disabilities. This program is premised on two principles: (1) Computer overuse injuries are entirely preventable. Sensible job design, proper workstation layout and healthy work practices minimize the risks of developing RSIs. (2) RSI prevention should be an ongoing occupational health and safety concern. A prevention program must not begin and end with a pamphlet or information session. Vigorous efforts are required to guarantee the health and safety of persons with disabilities who rely on adaptive technologies. This program might include:
Despite growing public awareness about RSIs, misunderstandings about the causes, magnitude and severity of the problem persist. The RSI problem is particularly acute for persons with disabilities because (1) individuals who rely on assistive devices are exposed to multiple risk factors; (2) chronic RSI doubly disables a person with a disability; and (3) reliable information about computer-induced overuse injuries is not always available in accessible formats. As persons with disabilities increasingly benefit from compensatory technologies, many, through no fault of their own, may be injured by the very devices that are intended to level the playing field. Thus it is urgent to develop RSI prevention programs; to reexamine workplace policies that make it possible for overuse injuries to occur; and to strengthen legislation that protects the rights of injured workers, able-bodied and disabled alike. With the outbreak of new RSI cases anticipated in the coming years, the line separating able-bodied from disabled persons will likely begin to dissolve.
1. There is an ongoing e-mail discussion group on the subject of typing injuries called SOREHAND. To subscribe, e-mail the following message to email@example.com:
subscribe sorehand Firstname Surname
2. Internet data archives contain current information about typing injuries. To access the archives, anonymous ftp to:
Bureau of National Affairs. (1991). Cumulative trauma disorders in the workplace: costs, prevention, and progress. Washington D.C.: Bureau of National Affairs.
Canadian Centre for Occupational Health and Safety. (November 1989). Ergonomic infogram: VDT workplace. Hamilton: Canadian Centre for Occupational Health and Safety.
Cantor, Alan. (1993). Preventing repetitive strain injuries: a guide for graduate students. Booklet published by the Graduate Students Union, University of Toronto.
Drewczynski, Andrew. (April 1990). Working in a sitting position. Hamilton: Canadian Centre for Occupational Health and Safety.
Ontario Women's Directorate. (1991). Case study: ergonomics: tackling repetitive strain. Toronto: Ontario Women's Directorate.
Parker, Kathryn G. and Imbus, Harold R. (1992). Cumulative trauma disorders: current issues and ergonomic solutions: a systems approach. Boca Raton: Lewis Publishers.
Pascarelli, Emil and Quilter, Deborah. (1994). Repetitive strain injuries: a computer user's guide. New York: John Wiley & Sons, Inc.
Taylor, Paul. (27, 28, 29, 30, 31 December 1993). The Globe and Mail. Keyboard grief: coping with computer caused injuries.
Workers' Compensation Board of British Columbia. (1994). Draft ergonomics regulations and: statement of context, draft code of practice, proposed implementation strategy. Richmond B.C.
Workplace Health and Safety Agency. (July 1992). Musculoskeletal injuries prevention program. Participant's manual. Toronto.
I thank the Ontario Ministry of Labour for supporting this research, and A. Wayne Evans, M.D. (Toronto Hospital), Barbara Roberts, M.S. OTR (Queen's University at Kingston), and Helen Simson, M.A. (Ontario Institute for Studies in Education) for critiquing this paper.