Repetitive Stress Injuries & |  | by Brooke E. Smith |
Everybody knows that using a computer keyboard can cause repetitive stress injuries. After all, we're being bombarded with stories in the popular press about the number of employees who have become disabled from keyboard work. We're constantly being told how to prevent "ergonomic" ills through use of special chairs, keyboards, and other devices. And if it's too late for prevention, billboards for hand surgeons offer quickie cures for carpal tunnel syndrome and other so-called cumulative trauma disorders.
However, before you pay off the next workman's compensation claim by a computer operator, or purchase a wrist rest for your own use while keyboarding, consider that scientific evidence linking computers with carpal tunnel syndrome or any other medical condition is strangely lacking. When doctors, ergonomists, attorneys, or anyone else are asked to provide reliable scientific evidence that these conditions are actually caused by computer use, they fail to do so. For this reason, every single lawsuit brought by a computer operator claiming damages based on keyboard use that has gone to trial has ended up in a judgment for the defense. Moreover, cities such as Miami who have required their employees to prove that their injuries were caused by computer use in order to get workman's compensation payments have avoided paying out any taxpayer dollars on these claims.
Absent the hype by plaintiff's lawyers, chiropractors, inventors of ergonomic devices, and others profiting from the repetitive stress injury epidemic, the essential facts about these conditions are as follows:
1. What is a "cumulative trauma disorder" or "repetitive stress injury"?
Neither "cumulative trauma disorder" ("CTD") nor "repetitive stress injury" ("RSI") is a specific medical condition. Some limit use of the term "CTD" to conditions arising from obvious trauma or injury that occurs more than once, such as might be experienced by someone who sustained multiple but separate injuries to his back from playing football on different occasions over the years. In contrast, the term "RSI" is often applied to repetitive activity which is not inherently harmful or injurious, but which is alleged to become so due to the sheer number of repetitions or the presence of other circumstances which "stress" the body.
In the context of keyboard use, the terms CTD and RSI have often been applied to a wide range of different medical conditions, including tendinitis, De Quervain's syndrome, trigger finger, epicondylitis, muscle fatigue and bursitis, as well as carpal tunnel syndrome ("CTS"). Not only are each of these a separately diagnosable condition with specific and different causes and treatments, but each affects a different part of the human body; for example, trigger finger concerns individual fingers, while epicondylitis ("tennis elbow") is associated with pain in a completely unrelated joint.
2. What problems are caused by lumping these conditions under the terms "CTD" or "RSI"?
By dealing with these separate medical conditions under the umbrella of "CTD" or "RSI", proponents of the epidemic blur the distinctions necessary to understand what scientific evidence exists regarding computer use and the alleged causation of these medical problems. For example, they can't show you a study linking computer use to development of epicondylitis; none have been done. They can't explain why operating the same system would cause one person to have problems with her fingers, while affecting another's back or shoulder instead. And they completely avoid the critical question: why the vast majority of people experience no problems whatsoever from their computer work.
By referring to a whole family of unrelated conditions rather than focusing on specific medical problems, users of the terms "CTD" and "RSI" can conveniently extrapolate from one condition to another. Anecdotal information linking a long day of computer use with muscle fatigue thus inappropriately becomes "proof" that keyboarding also "causes" CTS. Soon everything becomes associated with everything else, though not by any logical or scientifically rigorous means.
3. What is carpal tunnel syndrome (CTS)?
Most of the publicity has focused on CTS, which is an upper extremity disorder resulting from compression of the median nerve within the carpal tunnel, or wrist area of the hand. A person is only properly diagnosed as having CTS when symptoms such as tingling, numbness, swelling, lack of grip strength, or pain are present in the hand, and when a nerve conduction study confirms that the median nerve is reacting abnormally slowly.
The nerve conduction test is essential, because many people may have the symptoms of CTS while having normal nerve conduction. However, medical providers do not uniformly require their patients to have nerve conduction studies performed before making a diagnosis of CTS. Therefore, statistics regarding the incidence of CTS in the general population are likely skewed in favor of overdiagnosis of the condition.
4. Does operating a computer cause CTS?
For there to be a causal link between typing on a computer keyboard and developing CTS, the median nerve would have to be compressed as a direct result of that specific activity. However, internationally-known hand surgeon Peter A. Nathan of Portland, Oregon, who has conducted many studies analyzing the hand-activity components in a wide variety of job categories, has been unable to identify any job-related activity (including keyboarding) which produces biomechanical forces sufficient to compress the median nerve at the wrist.
While some medical experts speculate that the median nerve may be compressed when pressure in the carpal tunnel rises, and that typing with a bent wrist may cause a temporary rise in carpal tunnel pressure, no one has been able to provide reliable scientific evidence linking a temporary rise in pressure to development of CTS. Rather, studies conducted by Dr. Nathan and others support the opposite conclusion: the activity of keyboard use is not associated with the development of carpal tunnel syndrome.
5. Does operating a computer cause any other medical problem?
But even if there is no valid scientific study linking computer use with CTS, what about the other so-called CTDs such as tendinitis? Surely if a good word processor strikes keys thousands of times, day after day, it stands to reason that the sheer number of repetitions could cause injury.
Not true, according to Nortin M. Hadler, M.D., Professor of Medicine and Microbiology/Immunology at the University of North Carolina School of Medicine. Dr. Hadler has determined that repetitive motion is not hazardous to a person performing a task when the elements of the task are themselves customary and comfortable, and the number of repetitions are not patently unreasonable. On the basis of extended studies, Dr. Hadler concludes that there is no valid scientific basis for finding that CTDs are caused by such reasonable repetitive motion. In fact, one study performed by Dr. Nathan indicates that keyboard use and repetition in general protect against the development of CTS.
6. So what is causing the epidemic of reports of CTS in computer operators?
As mentioned above, there is considerable doubt as to the number of actual CTS cases among those being diagnosed as such. There is also a lack of valid epidemiological studies regarding the incidence of CTS in the non-working (or non-computer-using) population. As a result, there is no way to accurately determine whether there is an epidemic present.
Although there is a paucity of scientific evidence linking computer use to CTS, a number of studies have been performed associating this disease with various personal factors. The probability that a person will be diagnosed as having CTS increases if the person is (1) female; (2) over the age of forty; (3) overweight; (4) has diabetes, arthritis or hormone disorders; or (5) has ever had a hysterectomy. Personal habits such as use of tobacco, alcohol and caffeine and failure to exercise regularly also raises the likelihood that a person will develop CTS. Also, psychosocial factors which determine whether a person is undergoing stress at work or at home, such as employer/employee relationships, work changes, and other elements which may affect someone's overall satisfaction with life are also thought to play an important part in separating those who develop CTS from those who don't. Finally, a number of medical providers believe that a large number of cases of CTS have no discernible cause.
7. If computer use doesn't cause CTS, why do so many people associate their symptoms with keyboarding?
It is possible that even if working on a computer does not cause CTS or any other medical condition, an already-existing disease may manifest itself during a particular activity. For example, a person who suffers from angina may have no symptoms while sitting on the couch watching television, but may experience chest pains on walking up a flight of stairs. In this case, neither the act of walking - nor the stairs themselves - would be the cause of the angina, though it might seem so to the person involved.
As it currently stands, a person is likely to want to associate their condition with keyboard use, especially work-related keyboard use, because that's what the social and economic system favors. A person whose CTS is ascribed to on-job computer operation is eligible for medical treatment and off-work salary payments through workman's compensation, and may also join the hundreds of plaintiffs trying to get damages (although unsuccessfully) from manufacturers and suppliers. It is also easier to place the blame on a piece of equipment than to revise one's lifestyle.
8. Does it help to use ergonomic equipment for computer use?
Just as there is no valid scientific study showing that computer use causes any medical problems, there are no scientific studies demonstrating that use of a wrist rest or "ergonomic" chair or keyboard will lessen the risk of the user developing CTS or any other upper extremity disorder. The better question may be whether any of this equipment will cause harm.
While a comfortable chair, whether ergonomic or not, is unlikely to be a problem, the use of the widely-heralded wrist rests is highly controversial. As originally conceived, wrist rests were meant to provide a soft place for a computer user's hands to rest while not keying. (As pointed out by Dr. Harry Snyder, former chair of the committee which promulgated national standards for computer workstation and keyboard design, one's lap works just as well.) However, most users put their hands on the wrist rest while actually typing. Because this results in external pressure being placed on the user's carpal tunnel, for those who believe that computer use is associated with CTS, the use of a wrist rest would seem as likely to increase the risk as reduce it.
Likewise, specially-designed keyboards have not been shown to do anything more than cause added stress and frustration to their users - factors which have been associated through scientific studies with high risks of CTS. Use of wrist splints has been associated with muscle atrophy, and in the case of splints which cause a high degree of flexion, with a rise in carpal tunnel pressure.
The extreme differences in opinion among the scientific and ergonomic communities in this area is illustrated in the controversy regarding the design and use of ergonomic equipment, but is not in any way confined to this issue. Contrary to what you may have heard before, there is simply no consensus that computer use has ever harmed anyone. So before you join the epidemic - or become another of its victims - get the facts.
Brooke E. Smith, a HAL-PC member, is an attorney in the Houston office of Leonard Hurt Terry & Blinn P.C.
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