Introduction
VDU operators commonly report musculoskeletal problems in the neck, shoulders and upper limbs. These problems are not unique to VDU operators and are also reported by other workers performing tasks which are repetitive or which involve holding the body in a fixed posture (static load). Tasks which involve force are also commonly associated with musculoskeletal problems, but such tasks are not generally an important health and safety consideration for VDU operators.
Among clerical workers, whose jobs are generally sedentary and not commonly associated with physical stress, the introduction into workplaces of VDUs caused work-related musculoskeletal problems to gain in recognition and prominence. Indeed, an epidemic-like increase in reporting of problems in Australia in the mid 1980s and, to a lesser extent, in the United States and the United Kingdom in the early 1990s, has led to a debate about whether or not the symptoms have a physiological basis and whether or not they are work-related.
Those who dispute that musculoskeletal problems associated with VDU (and other) work have a physiological basis generally put forward one of four alternative views: workers are malingering; workers are unconsciously motivated by various possible secondary gains, such as workers’ compensation payments or the psychological benefits of being sick, known as compensation neurosis; workers are converting unresolved psychological conflict or emotional disturbance into physical symptoms, that is, conversion disorders; and finally, that normal fatigue is being blown out of proportion by a social process which labels such fatigue as a problem, termed social iatrogenesis. Rigorous examination of the evidence for these alternative explanations shows that they are not as well supported as explanations which posit a physiological basis for these disorders (Bammer and Martin 1988). Despite the growing evidence that there is a physiological basis for musculoskeletal complaints, the exact nature of the complaints is not well understood (Quintner and Elvey 1990; Cohen et al. 1992; Fry 1992; Helme, LeVasseur and Gibson 1992).
Symptom Prevalence
A large number of studies have documented the prevalence of musculoskeletal problems among VDU operators and these have been predominantly conducted in western industrialized countries. There is also growing interest in these problems in the rapidly industrializing nations of Asia and Latin America. There is considerable inter-country variation in how musculoskeletal disorders are described and in the types of studies carried out. Most studies have relied on symptoms reported by workers, rather than on the results of medical examinations. The studies can be usefully divided into three groups: those which have examined what can be called composite problems, those which have looked at specific disorders and those which have concentrated on problems in a single area or small group of areas.
Composite problems
Composite problems are a mixture of problems, which can include pain, loss of strength and sensory disturbance, in various parts of the upper body. They are treated as a single entity, which in Australia and the United Kingdom is referred to as repetitive strain injuries (RSI), in the United States as cumulative trauma disorders (CTD) and in Japan as occupational cervicobrachial disorders (OCD). A 1990 review (Bammer 1990) of problems among office workers (75% of the studies were of office workers who used VDUs) found that 70 studies had examined composite problems and 25 had found them to occur in a frequency range of between 10 and 29% of the workers studied. At the extremes, three studies had found no problems, while three found that 80% of workers suffer from musculoskeletal complaints. Half of the studies also reported on severe or frequent problems, with 19 finding a prevalence between 10 and 19%. One study found no problems and one found problems in 59%. The highest prevalences were found in Australia and Japan.
Specific disorders
Specific disorders cover relatively well-defined problems such as epicondylitis and carpal tunnel syndrome. Specific disorders have been less frequently studied and found to occur less frequently. Of 43 studies, 20 found them to occur in between 0.2 and 4% of workers. Five studies found no evidence of specific disorders and one found them in between 40–49% of workers.
Particular body parts
Other studies focus on particular areas of the body, such as the neck or the wrists. Neck problems are the most common and have been examined in 72 studies, with 15 finding them to occur in between 40 and 49% of workers. Three studies found them to occur in between 5 and 9% of workers and one found them in more than 80% of workers. Just under half the studies examined severe problems and they were commonly found in frequencies that ranged between 5% and 39%. Such high levels of neck problems have been found internationally, including Australia, Finland, France, Germany, Japan, Norway, Singapore, Sweden, Switzerland, the United Kingdom and the United States. In contrast, only 18 studies examined wrist problems, and seven found them to occur in between 10% and 19% of workers. One found them to occur in between 0.5 and 4% of workers and one in between 40% and 49%.
Causes
It is generally agreed that the introduction of VDUs is often associated with increased repetitive movements and increased static load through increased keystroke rates and (compared with typewriting) reduction in non-keying tasks such as changing paper, waiting for the carriage return and use of correction tape or fluid. The need to watch a screen can also lead to increased static load, and poor placement of the screen, keyboard or function keys can lead to postures which may contribute to problems. There is also evidence that the introduction of VDUs can be associated with reductions in staff numbers and increased workloads. It can also lead to changes in the psychosocial aspects of work, including social and power relationships, workers’ responsibilities, career prospects and mental workload. In some workplaces such changes have been in directions which are beneficial to workers.
In other workplaces they have led to reduced worker control over the job, lack of social support on the job, “de-skilling”, lack of career opportunities, role ambiguity, mental stress and electronic monitoring (see review by Bammer 1987b and also WHO 1989 for a report on a World Health Organization meeting). The association between some of these psychosocial changes and musculoskeletal problems is outlined below. It also seems that the introduction of VDUs helped stimulate a social movement in Australia which led to the recognition and prominence of these problems (Bammer and Martin 1992).
Causes can therefore be examined at individual, workplace and social levels. At the individual level, the possible causes of these disorders can be divided into three categories: factors not related to work, biomechanical factors and work organization factors (see table 1). Various approaches have been used to study causes but the overall results are similar to those obtained in empirical field studies which have used multivariate analyses (Bammer 1990). The results of these studies are summarized in table 1 and table 2. More recent studies also support these general findings.
Table 1. Summary of empirical fieldwork studies which have used multivariate analyses to study the causes of musculoskeletal problems among office workers
|
Factors |
||||
|
|
|
|
|
Work organisation |
|
Blignault (1985) |
146/90% |
ο |
ο |
● |
|
South Australian Health Commission Epidemiology Branch (1984) |
456/81% |
●
|
●
|
●
|
|
Ryan, Mullerworth and Pimble (1984) |
52/100% |
● |
●
|
●
|
|
Ryan and |
143 |
|||
|
Ellinger et al. (1982) |
280 |
● |
●
|
● |
|
Pot, Padmos and |
222/100% |
not studied |
● |
● |
|
Sauter et al. (1983b) |
251/74% |
ο |
●
|
● |
|
Stellman et al. (1987a) |
1, 032/42% |
not studied |
●
|
● |
ο = non-factor ●= factor.
Source: Adapted from Bammer 1990.
Table 2. Summary of studies showing involvement of factors thought to cause musculoskeletal problems among office workers
|
Non-work |
Biomechanical |
Work organization |
|||||||||||||
|
Country |
No./% VDU |
Age |
Biol. |
Neuro ticism |
Joint |
Furn. |
Furn. |
Visual |
Visual |
Years |
Pressure |
Autonomy |
Peer |
Variety |
Key- |
|
Australia |
146/ |
Ø |
Ø |
Ø |
Ø |
Ο |
● |
● |
● |
Ø |
|||||
|
Australia |
456/ |
● |
Ο |
❚ |
Ø |
Ο |
● |
Ο |
|||||||
|
Australia |
52/143/ |
▲ |
❚ |
❚ |
Ο |
Ο |
● |
Ο |
|||||||
|
Germany |
280 |
Ο |
Ο |
❚ |
Ø |
❚ |
Ο |
Ο |
● |
● |
Ο |
||||
|
Netherlands |
222/ |
❚ |
❚ |
Ø |
Ø |
Ο |
● |
(Ø) |
Ο |
||||||
|
United States |
251/ |
Ø |
Ø |
❚ |
❚ |
Ο |
● |
(Ø) |
●
|
||||||
|
United States |
1,032/ |
Ø |
❚ |
❚ |
Ο |
● |
● |
||||||||
Ο = positive association, statistically significant. ● = negative association, statistically significant. ❚ = statistically significant association. Ø = no statistically significant association. (Ø) = no variability in the factor in this study. ▲ = the youngest and the oldest had more symptoms.
Empty box implies that the factor was not included in this study.
1 Matches references in table 52.7.
Source: adapted from Bammer 1990.
Factors not related to work
There is very little evidence that factors not related to work are important causes of these disorders, although there is some evidence that people with a previous injury to the relevant area or with problems in another part of the body may be more likely to develop problems. There is no clear evidence for involvement of age and the one study which examined neuroticism found that it was not related.
Biomechanical factors
There is some evidence that working with certain joints of the body at extreme angles is associated with musculoskeletal problems. The effects of other biomechanical factors are less clear-cut, with some studies finding them to be important and others not. These factors are: assessment of the adequacy of the furniture and/or equipment by the investigators; assessment of the adequacy of the furniture and/or equipment by the workers; visual factors in the workplace, such as glare; personal visual factors, such as the use of spectacles; and years on the job or as an office worker (table 2).
Organizational factors
A number of factors related to work organization are clearly associated with musculoskeletal problems and are discussed more fully elsewhere is this chapter. Factors include: high work pressure, low autonomy (i.e., low levels of control over work), low peer cohesion (i.e., low levels of support from other workers) which may mean that other workers cannot or do not help out in times of pressure, and low task variety.
The only factor which was studied for which results were mixed was hours using a keyboard (table 2). Overall it can be seen that the causes of musculoskeletal problems on the individual level are multifactorial. Work-related factors, particularly work organization, but also biomechanical factors, have a clear role. The specific factors of importance may vary from workplace to workplace and person to person, depending on individual circumstances. For example, the large-scale introduction of wrist rests into a workplace when high pressure and low task variety are hallmarks is unlikely to be a successful strategy. Alternatively, a worker with satisfactory delineation and variety of tasks may still develop problems if the VDU screen is placed at an awkward angle.
The Australian experience, where there was a decline in prevalence of reporting of musculoskeletal problems in the late 1980s, is instructive in indicating how the causes of these problems can be dealt with. Although this has not been documented or researched in detail, it is likely that a number of factors were associated with the decline in prevalence. One is the widespread introduction into workplaces of “ergonomically” designed furniture and equipment. There were also improved work practices including multiskilling and restructuring to reduce pressure and increase autonomy and variety. These often occurred in conjunction with the implementation of equal employment opportunity and industrial democracy strategies. There was also widespread implementation of prevention and early intervention strategies. Less positively, some workplaces seem to have increased their reliance on casual contract workers for repetitive keyboard work. This means that any problems would not be linked to the employer, but would be solely the worker’s responsibility.
In addition, the intensity of the controversy surrounding these problems led to their stigmatization, so that many workers have become more reluctant to report and claim compensation when they develop symptoms. This was further exacerbated when workers lost cases brought against employers in well-publicized legal proceedings. A decrease in research funding, cessation in publication of incidence and prevalence statistics and of research papers about these disorders, as well as greatly reduced media attention to the problem all helped shape a perception that the problem had gone away.
Conclusion
Work-related musculoskeletal problems are a significant problem throughout the world. They represent enormous costs at the individual and social levels. There are no internationally accepted criteria for these disorders and there is a need for an international system of classification. There needs to be an emphasis on prevention and early intervention and this needs to be multifactorial. Ergonomics should be taught at all levels from elementary school to university and there need to be guidelines and laws based on minimum requirements. Implementation requires commitment from employers and active participation from employees (Hagberg et al. 1993).
Despite the many recorded cases of people with severe and chronic problems, there is little available evidence of successful treatments. There is also little evidence of how rehabilitation back into the workforce of workers with these disorders can be most successfully undertaken. This highlights that prevention and early intervention strategies are paramount to the control of work-related musculoskeletal problems.