To The Editor:
I am writing with regard to the Current Concepts Review entitled
"Repetitive Stress Injury: Diagnosis or Self-Fulfilling Prophecy?"
(82-A: 1314-1322, Sept. 2000), by Szabo and King. The authors of
the article review a specific legal case of keyboard use as a cause
of repetitive stress injury (RSI) and also discuss the topic of
overuse injuries in the workplace in general. It is undoubtedly
true that the evidence associating keyboard use with specific injuries
is weak, that the benefit of ergonomically motivated changes in
keyboard design is unknown, and that the use of the term RSI as
a specific diagnosis is ill-advised. However, in generalizing from
a specific case of keyboard use as a cause of a specific entity
called RSI to the larger issues of repetitive activity as a cause
of injury in the workplace and the role of ergonomics in understanding
and reducing such injuries, Szabo and King move from firm to far shakier
ground.
First, they greatly overstate the magnitude and locus of the
problem, possibly because they use outdated data. The data that
they cite are from 1992 and were obtained from Bureau of Labor Statistics
(BLS) reports. These annual reports track all work-related musculoskeletal
disorders (WRMSDs), from fractures and lacerations to the dreaded RSI.
The most recent data are from 1998. According to these reports,
both the rate and the absolute number of WRMSDs peaked in 1993 and
have been diminishing, in all categories, ever since1. The number
of cases of carpal tunnel syndrome (CTS) resulting in lost work
days, for example, has dropped by more than 30%, to roughly 26,000
in 1998, for a rate of three per 10,000 workers1. The rate of such
cases in which repetitive motion was implicated has likewise decreased,
to 7.4 per 10,000 workers (less than 5% of all WRMSDs reported in
the 1998 BLS data)1. Acute transient injury such as back strain
was the most common category of WRMSD, representing more than one-half
of the total, followed by injuries due to falls, injuries due to
machinery, fractures, and lacerations. Furthermore, clerical workers
had few WRMSDs of any sort; the most common occupations cited in
the BLS list were truck drivers, laborers, and hospital orderlies, with
secretaries ranked last at forty-third. Thus, rather than "an epidemic
of so-called work-related musculoskeletal problems," the BLS data
demonstrate a moderate and steadily diminishing number of cases,
concentrated in just the sorts of jobs that one would expect: occupations requiring
heavy lifting, gripping, and high-force/high-repetition work, which
often are associated with awkward postures as well. One can only
speculate with regard to the reason for the decrease in reported work-related
musculoskeletal problems, but ergonomic improvements in the workplace seem
to be a logical candidate, as will be discussed below. Other explanations
are unlikely. The decrease began long before the keyboard cases
received broad public attention, and the decline did not coincide
with a change in the legal status of certain WRMSDs, as occurred
in Australia.
The second issue relates to the documentation-or rather the lack
of it, as no references are cited-for the strong statements that
ergonomists have recommended legislation "on the basis of the unproved
claim that work-related musculoskeletal disorders are disabling
physical conditions" and that "they have not lowered the prevalence
of these disorders." As noted in the recent report by the Steering Committee
of the National Academy of Sciences (NAS) Workshop on Work-Related Musculoskeletal
Disorders, "one feature of the discourse around musculoskeletal
disorders is that it sometimes involves individuals from one discipline
(or subdiscipline) who reject entirely the legitimacy of research
from another."2 Perhaps it was unintended, but the use of strongly worded,
undocumented statements such as those above and headings such as
"Ergonomics Unchained" suggest at least the possibility that Szabo
and King are questioning the legitimacy of ergonomics as a scientific
discipline. If so, this is unjust. The data cited above clearly
show that the prevalence of WRMSDs has gone down, and, as the BLS definition
of WRMSDs includes fractures, lacerations, carpal tunnel syndrome,
and a variety of other specific conditions, perhaps we can agree
that at least some WRMSDs are disabling. But we can also use sources
cited by Szabo and King, provided that we are willing to read a
bit further in the sources themselves. For example, they refer to the
"stark observations" of the NAS report, which raises questions regarding
the quality of the data supporting repetition as an etiology of
musculoskeletal injury. The four bulleted items quoted by Szabo
and King do indeed appear on page 15 of the NAS report2. The very
next, and concluding, sentence of that section was, however, not
included in the quote. It states: "Despite these limitations, the
steering committee reached the following conclusions: restricting
our focus to those studies involving the highest levels of exposure
to biomechanical stressors . . . the positive relationship between
the occurrence of musculoskeletal disorders and the conduct of work
is clear," and "there is compelling evidence from numerous studies
that as the amount of biomechanical stress is reduced, the prevalence
of musculoskeletal disorders in the affected body region is likewise reduced."2
Nor do Szabo and King make any mention of the final conclusions
of the NAS report, which are listed on pages 27 and 28 of that document. These
are:
(1) There is a higher incidence of reported pain, injury, loss
of work, and disability among individuals who are employed in occupations
where there is a high level of exposure to physical loading than
for those employed in occupations with lower levels of exposure.
(2) There is a strong biological plausibility to the relationship between
the incidence of musculoskeletal disorders and the causative exposure
factors in high exposure occupational settings.
(3) Research clearly demonstrates that specific interventions can
reduce the reported rate of musculoskeletal disorders for workers
who perform high risk tasks. No known single intervention is universally
effective. Successful interventions require attention to individual,
organizational and job characteristics, tailoring the corrective
actions to those characteristics2.
Thus, although Szabo and King are correct in stating that the NAS
report found the literature on the subject to be imperfect (and
what scientific literature is not?), they fail to convey the fact that
the NAS report clearly concluded that the available evidence was
quite sufficient to tie certain injuries to repetitive activity
and that ergonomic interventions (that is, interventions designed
to reduce biomechanical stress) were effective in reducing these
injuries.
There are similar problems with other citations. For example, Szabo
and King cite the article by Atroshi et al.3 to support the statement
that "the prevalence of carpal tunnel syndrome is the same whether
or not people perform repetitive activities." Yet Atroshi et al.
reported that the prevalence of CTS was 5.4% for those doing as
little as one hour of repetitive work per day compared with 1.8%
for those doing no repetitive work, a highly significant difference
(p < 0.001). Atroshi et al. further noted that excessive wrist
flexion and exposure to vibration also were associated with a significantly
higher prevalence of CTS in their population-based study.
As a final observation, it is ironic that this article appeared
at the same time as an article in BMJ by Macfarlane et al., who reported
that a prospective analysis of nearly 2000 individuals showed that
both repetitive activity (relative risk, 4.1) and workplace dissatisfaction
(relative risk, 4.7) were important risk factors for the work-related
musculoskeletal symptom of forearm pain4. It seems reasonable to conclude
that both repetitive work and psychosocial factors are important
predictors of musculoskeletal symptoms in the workplace, such as
those experienced by the workers in the keyboard lawsuits. Moreover, numerous
studies of humans2,3,5-12 and animals13-16 have shown that repetitive loading13-16,
vibration7,9,12, and awkward posture3,17 can produce a host of musculoskeletal
pathologies, including disc degeneration15, tendon degeneration13,16,
rotator cuff disease14, and carpal tunnel syndrome3,8,11,18, as
well as regional pain such as that studied by Macfarlane et al.4,
which in many cases may be due to exercise-induced muscle injury5,19-22.
In short, although this paper is certainly a well-documented summary
of the keyboard/RSI legal defense, I found it rather disappointing
in its attempt to serve as a Current Concepts Review of the broader
topic of repetitive activity in the workplace and in its broad,
poorly documented critiques of repetition as a potential cause of
musculoskeletal injury and of the field of ergonomics in general. This
broader subject deserves more thorough coverage in the pages of
The Journal of Bone and Joint Surgery.
-Peter C. Amadio, MDMayo Clinic
200 First Street S.W.
Rochester, MN 55905
E-mail address: pamadio@mayo.edu
To The Editor:
Dr. Szabo and Atty. King's Current Concepts Review, "Repetitive
Stress Injury: Diagnosis or Self-Fulfilling Prophecy?" (82-A: 1314-1322,
Sept. 2000), raises a number of important issues for all orthopaedists.
Their position is cause for concern for three reasons. First, their
attempt to debunk computer keyboards as a cause of a work-related
musculoskeletal disorder (WRMSD) might lead the reader to decide that
there is little scientific information about the causation or prevention
of all WRMSDs. That simply is not true. Second, like the American
Academy of Orthopaedic Surgeons, they assert that there currently
is insufficient scientific information about WRMSDs. This statement
puts our profession in a tenuous position and raises the question,
"Do we apply a different standard regarding the scientific basis
for many of our diagnoses and treatments compared with that for
WRMSDs?" Third, they infer that many of these syndromes are "functional somatic
symptoms" and cite the Australian experience. Perhaps some WRMSDs
have a "functional somatic component," but if we generalize that
bias to most of our patients with WRMSDs we risk losing our hard-earned position
as their advocate.
This article comes at a time when the Academy has taken the public
position that there is inadequate scientific information for the
Occupational Safety and Health Administration (OSHA) to increase
the regulation of American industries by including more ergonomic
interventions. As a former CEO of a large health-care organization,
I experienced firsthand the negative impact of OSHA's overbearing
policies. It is difficult to separate the science from the public
policy debate, but as orthopaedists we need to take a more even-handed
approach.
In 1986, Dr. Vert Mooney and I co-authored a Current Concepts Review
entitled "Occupational Orthopaedics."23 We summarized the then-available
literature and concluded that the data on many (but not all) upper-extremity
and spinal disorders were sufficiently convincing to ascribe the
workers' symptoms to workplace causality. Furthermore, these conditions
appeared to result from repetitive loads. Although a precise "dose-response"
could not be quantified, a relationship did exist between symptoms,
load, posture, and repetitions over time. Since that time, there
has been a great deal of additional basic-science, epidemiological,
and interventional research on this topic. Despite these data, Dr.
Szabo and Atty. King iterate that there is insufficient scientific
evidence for the determination of causality or prevention efficacy.
Are we applying a double standard to how we view scientific merit?
A great deal of our diagnostic and therapeutic decisions in the day-to-day
practice of orthopaedics are based on information that could be
considered insufficient. For example, in 1992, Turner et al. synthesized
the then-available data about spinal fusion24. Their study-selection criteria
were far less stringent than the criteria used by the National Research
Council in its deliberations on "Work-Related Musculoskeletal Disorders."2
In the report by Turner et al., "articles were selected only if
they reported at least 1 year follow-up data enabling the classification of
clinical outcomes as satisfactory or unsatisfactory for at least 30
patients." Only forty-seven articles met their criteria, and there
were no randomized trials. Only four articles compared the outcomes
for patients who had fusion with those for patients who had no fusion.
Spinal fusion is often performed for patients receiving Workers'
Compensation. The clinical criteria that lead to the therapeutic
decision often are vague, with the procedure being performed for
such conditions as "degenerative disc disease," "black disc disease," and
"segmental instability." In population-based studies, the clinical
outcomes are generally poor25. The truth is that a great deal of
our clinical decisions still are based on retrospective, uncontrolled
data that are no better, and quite possibly are less scientific,
than the data supporting WRMSDs.
It is not my intention to debunk spinal fusion but to point out that,
in comparison, the literature on WRMSDs includes a great deal of
epidemiological data and prospective, randomized, controlled studies
as well as documented case studies. It is perplexing that a profession
that embraces "overuse syndromes" in athletes has difficulty accepting
the notion that chronic repetitive trauma can cause symptoms, disorders,
and even injuries in the workplace. One trip to an assembly plant
will convince most observers that the "exposures" are at least as demanding
as most athletics. In short, are we using a double standard to evaluate
the literature?
The notion that many of these conditions are clouded by somatization
puts us, as orthopaedists, in an awkward position as our patients'
advocates. The evolution of our understanding of disease usually
starts with a description of symptoms. Often much later, physical
signs or other sophisticated tests become available and the pathophysiology
is then understood. One definition of somatization is the description
of physical symptoms that cannot be confirmed by physical examination
or other tests. Another definition adds the requirement for a likely
psychological cause, of which depression and anxiety are common antecedents.
Regardless of its definition, somatization is separable from malingering
and factitious disorders, which are uncommon and for which the authors
of the Diagnostic and Statistical Manual of Mental Disorders, Fourth
Edition: Primary Care Version (DSM-IV-PC) have established specific
criteria. Somatization, depression, and anxiety (but not malingering)
are common attributes of patients with chronic, disabling musculoskeletal
conditions related or unrelated to the workplace. It is also true
that compensation is associated with a greater risk for later disability26 as
well as later litigation27. Whether intended or not, the context
of the authors' remarks might lead the reader to conclude that the
majority of WRMSDs are minimally related to physical exposures and
are predominantly due to psychological dysfunction. The Academy's,
and I presume the authors', legitimate concerns about OSHA's often misguided
application of public policy cannot be allowed to override our more
fundamental concern for our patients.
To the four responsibilities listed by the authors, I would add
a fifth. As clinicians treating patients, we need to better understand
the environment in which patients work and the physical and psychosocial
stresses to which they are subjected. One trip to an assembly line
or a construction site will convince most that many workers experience major
physical stresses. If we believe that our patients' recovery is
impeded by significant psychosocial issues, isn't it is our responsibility
to direct the patients to the appropriate health professionals?
To paraphrase Sir William Osler, we should be more concerned about
the patient who has a disease than we are about the disease that
the patient has.
Note: The author of this letter serves on the second Institute
of Medicine Task Force. The opinions represented here are solely his
own.
-John Frymoyer, MD1450 Braeloch Road
Colchester, VT 05446
E-mail address: tofrys@aol.com
Dr. Szabo and Atty. King reply:
We agree with Dr. Amadio that "it is undoubtedly true that the evidence
associating keyboard use with specific injuries is weak, that the
benefit of ergonomically motivated changes in keyboard design is
unknown, and that the use of the term RSI as a specific diagnosis
is ill-advised." But, having made this concession, Dr. Amadio falls prey
to the same faulty logic and unsupported assertions that have so
often characterized the debate on this issue while, in the meantime,
patients continue to be misdiagnosed with "repetitive stress injuries"
attributed to poor ergonomics. In his letter, Dr. Amadio prefaces
purported scientific conclusions regarding the curative power of
ergonomics and the evils of repetition with tepid phrases such as
"one can only speculate" and "it seems reasonable to conclude that."
The use of such phrases demonstrates the lack of scientific support
for the points he makes. As one who holds himself out as a scientist, Dr.
Amadio should know better. We address several of his more flagrant
misstatements in turn.
Dr. Amadio confidently declares that we "greatly overstate the magnitude
and locus of the problem, possibly because [we] use outdated data."
However, he then mischaracterizes the very data upon which his statement
is based. For example, a review of the same data to which he refers reveals
that the number of "disorders associated with repeated trauma" increased
from 22,600 in 1982 to 332,100 in 1992 and then declined modestly
to 253,300 in 1998 (the most recent estimate). All reported illnesses associated
with any specific work or activity rose from 105,600 in 1982 to
514,700 in 1992 and similarly declined to 392,000 in 1998. When
one considers that the events attributed to repeated trauma have
risen from 21% to 65% of all reported illnesses from 1982 to 1998,
we believe that we stated accurately the "magnitude" as well as
the "locus" of the problem.
Similarly misguided is Dr. Amadio's reliance on the conclusions of
the National Academy of Sciences (NAS) report. As we state quite
clearly in our article, the NAS rendered its conclusions about "biomechanical
loads and biomechanical stressors" notwithstanding what it acknowledged
to be severe limitations in the literature. Our point, which Dr.
Amadio apparently missed, is that the conclusions drawn by the NAS
committee are not supported by meaningful data, and its concession
that it is "difficult to make strong causal references on the basis
of the evidence from any individual study" admits just that. When
we last checked, science is not based on leaps of faith but on meaningful
data. There are simply no studies, and Dr. Amadio has cited none,
that show that ergonomics prevents injury28.
At a minimum, Dr. Amadio's mixing of definitions and concepts
illustrates how individual studies are often misinterpreted in this
area to serve one's own ends. Thus, Dr. Amadio states that "there
are similar problems with other citations" and cites an example
where we accurately reported that Atroshi et al. found that "the
prevalence of carpal tunnel syndrome is the same whether or not
people perform repetitive activities."3 More specifically, Atroshi
et al. reported that the prevalence of carpal tunnel syndrome (CTS)
was 2.4% for workers who performed activities involving repetitive hand
or wrist motion compared with 2.7% for those who performed activities
involving nonrepetitive motion (95% confidence interval for the
difference, -2%, to -1.5%; p = 0.69)3. However, Dr. Amadio misrepresents
Atroshi's study with his statement that "Atroshi et al. reported
that the prevalence of CTS was 5.4% for those doing as little as
one hour of repetitive work per day compared with 1.8% for those
doing no repetitive work" [italics added]. Actually, Atroshi et
al. reported that the prevalence of CTS was 5.4% for working subjects
who self-reported that they used the hand for activities involving
excessive force for more than one hour per day compared with 1.8%
for those who reported less frequent or no such use3. The amount
of occupational exposure that corresponds with excessive force is not
described, but excessive force is nevertheless a different measure
than repetition.
We do not mean to denigrate the validity and benefits of ergonomics,
and we regret if Dr. Amadio was left with that impression. Nonetheless,
Dr. Amadio's statement that the "definition of WRMSDs includes fractures, lacerations
. . . and a variety of other specific conditions" is misleading
and not germane to the discussion of whether or not ergonomics has
reduced the incidence of "disabling conditions." In our opinion,
it is an injustice to the patient to rely on ergonomics to treat
medical conditions. "Repetitive stress injury" is not a diagnosis,
and the failure to make a correct diagnosis by labeling a patient
with RSI is very harmful as witnessed in the numerous "repetitive
stress injury" legal cases described in our report. The purpose
of our article was to educate those physicians, particularly orthopaedists,
who blindly get caught in the trap of labeling any upper extremity
pain syndrome as a work-related "repetitive stress injury," thereby
embroiling the patient in the medicolegal Workers' Compensation
system and, consequently, providing a disincentive for the patient
to get better. This serves neither the patient nor society.
Ergonomics cannot take credit for decreasing the incidence of well-recognized
chronic disorders of the upper extremity such as carpal tunnel syndrome.
Furthermore, there have been no reasonable interventional studies
(that is, studies in which both outcome and exposure are measured
and reported before and after an intervention) that have demonstrated
a decrease in the prevalence of injuries to the upper extremity
after the institution of ergonomic measures. An interventional study
should by definition be designed like any prospective, randomized,
controlled study. We have had the opportunity to review the literature
and, to the best of our knowledge, there have been no such studies.
This does not mean, as Dr. Amadio asserts, that we "reject entirely
the legitimacy of research from another" discipline or that we are
"questioning the legitimacy of ergonomics as a scientific discipline."
Rather, we recognize that ergonomics has some serious limitations.
For example, we reported the results of a specific interventional
study that clearly demonstrated that customary ergonomic measures
such as keyboard design, splinting, rest periods, and workstation
modifications did not relieve the incidence of "repetitive stress injury."
Before recommending ergonomic intervention legislation addressing
mechanical factors in the workplace, which would cost society billions
of dollars29, we believe that it is not too much to ask that these interventions
be shown to be effective.
Perhaps most disappointing is Dr. Amadio's touting of ergonomics
as the reason for any decline in WRMSDs. Regarding the Bureau of
Labor and Statistics (BLS) data, Dr. Amadio proclaims that "one
can only speculate with regard to the reason for the decrease in
reported work-related musculoskeletal problems, but ergonomic improvements
in the workplace seem to be a logical candidate." Not only do we
disagree, but we further note the complete lack of a scientific
approach to this "speculation," which is characteristic of Dr. Amadio's
purported analysis of our manuscript. A complete review of the very
BLS data he cites belies his theory. For example, not only was there
a decrease in reported work-related musculoskeletal problems from
1992 to 1998, but there also was a parallel decline in cases of
respiratory illnesses as well as in cases of poisoning and skin
diseases. Similarly, there has been a decline in the rate of nonfatal injuries
and illness among full-time workers in the agriculture, forestry,
fishing, and construction industries30. Does Dr. Amadio speculate
that these declines are also to be credited to ergonomic improvements?
Simply put, Dr. Amadio's logic is faulty and fails to distinguish
between an association on one hand and causation on the other. Just because
two variables are correlated does not mean that one causes the other.
For instance, ice cream sales and the number of shark attacks on
swimmers are correlated. Yet, in this case, both variables respond
to changes in some unobserved third variable: ice cream sales and
shark attacks both increase during the summer.
Are there competing hypotheses to explain the decline? As Susser stated:
"Insofar as epidemiology is a science which by definition aims to
discover the causes of health states, the search includes all determinants
of a health outcome."31 According to Linda Rosenstock, MD, director
of the National Institute of Occupational Safety and Health (NIOSH),
the workforce is aging and the incidence of injury decreases with
age32. The shift from manufacturing to less hazardous service industries
is creating safer working conditions32. Underreporting of actual
workplace injuries and illnesses to avoid visits by Occupational Safety
and Health Administration (OSHA) compliance officers has been proposed
by some to explain at least part of the decline32, although others
have refuted this explanation33. In short, we did not "speculate"
as to which of these competing hypotheses is best supported by the
data.
In his "final observation," Dr. Amadio asserts that "it is ironic" that
our paper was published simultaneously with the article in BMJ by
Macfarlane et al. Yet in that study, it was found that workplace
dissatisfaction was associated with a higher relative risk for forearm
pain than was repetitive activity and that "no increased risk was
associated with typing for more than 30 minutes without a break."4
From these findings, Dr. Amadio confidently states that "it seems
reasonable to conclude that both repetitive work and psychosocial
factors are important predictors of musculoskeletal symptoms in
the workplace, such as those experienced by the workers in the keyboard
lawsuits." Had Dr. Amadio had the benefit (as did one of the authors)
of reviewing the medical records of the numerous plaintiffs who
brought those lawsuits, he undoubtedly would have observed a myriad
of medical factors associated with those symptoms. He also would
have observed countless instances of patients mired in the Workers' Compensation
system who had been misdiagnosed with a "work-related repetitive
stress injury" and been told that proper ergonomics could have prevented
or even cured their condition. What we find ironic is that participants
in Macfarlane's study "who believed that they could rarely make
their own decisions at work had double the risk of new onset of
forearm pain."4 While Dr. Amadio apparently acknowledges that psychosocial
factors can account for such a large percentage of musculoskeletal
symptoms in the workplace, he fails to acknowledge that these factors
act as confounders and must be controlled for in studies that seek
to establish causation.
Putting aside the fact that the ambiguous diagnoses of forearm pain
and musculoskeletal symptoms are not synonymous with injury, we
found it extremely troublesome that Dr. Amadio (and Dr. Frymoyer)
do not acknowledge that low-force repetitive activities such as
typing (which, as indicated by Macfarlane's study, do not cause injury)
are different from high-force/high-impact athletic activities. We
also find it disappointing that Dr. Amadio failed to mention Macfarlane's
conclusions: "Psychological distress, aspects of illness behaviour,
and other somatic symptoms are important predictors of onset of forearm
pain in addition to work related psychosocial and mechanical factors.
Misleading terms such as `cumulative trauma disorder' or `repetitive strain
injury,' implying a single etiology should be avoided."4
Kuhn, in his thesis on scientific revolutions, argued that the
evidence that scientists draw upon is determined by an overriding contemporary
paradigm that dictates the way in which a causal sequence is construed34.
As studies like Macfarlane's reveal the overriding role that psychosocial
factors play in musculoskeletal symptoms associated with low-force
repetitive jobs, we are likely to see a paradigm shift that will
lead to more accurate diagnoses and better treatment and outcomes
for our patients. If we want our patients to feel better, we must
address the real causes of their pain. After all, would not Dr.
Amadio and Dr. Frymoyer agree that this is what makes us better
patient advocates?
-Robert M. Szabo, MD, MPHDepartment of Orthopaedics
University of California, Davis,
School of Medicine
4860 Y Street
Sacramento, CA 95817
E-mail address: rmszabo@ucdavis.edu
-Kenneth J. King, JDBrobeck, Phleger & Harrison
1633 Broadway, 47th Floor
New York, NY 10019
E-mail address: kking@brobeck.com