Civil Engineering Reference
In-Depth Information
2.2.1.2 Upper Extremity Disorders
A variety of disorders of the upper extremity were studied in the selected literature. Primary among these
was carpal tunnel syndrome, identified by symptoms and physical examination alone or in combination
with nerve conduction testing. A second important outcome was hand-arm vibration syndrome
(Raynaud's disease or other vibration-related conditions of the hand). There were also a number of oper-
ationally defined but les well-specified outcomes (defined for epidemiologic, not clinical, purposes) such
as musculoskeletal disorders of the wrist, tendinitis, and bone- or joint-related abnormalities. Studies that
met the most stringent criteria were not based on self-report alone. The anatomical areas with the greatest
number of studies were the hand and the wrist, although a number of studies focused more generally on
the upper extremities. Although a number of studies of the neck
shoulder region were considered, only
two were included. The neck, shoulders, and upper arms operate as a functional unit, which makes it dif-
ficult to estimate specific exposure factors for the neck
/
shoulder region at a level beyond that of job or job
tasks. Further complicating study of the region is the fact that most of the reported musculoskeletal pro-
blems of this region are nonspecific, without well-defined clinical diagnoses.
Table 2.3 provides a compilation of point estimates of risk from all studies across the major types of
work-related physical exposure that were studied. Appendix Table 2.5 presents the risk ratios for various
exposures; these ratios cover a very wise range (2-84), depending on how specifically the exposure and
the outcome were defined. With the exception of the few studies of bone- and joint-related abnormalities,
most of the results demonstrate a significant positive association between upper extremity musculo-
skeletal disorders and exposure to repetitive tasks, forceful tasks, the combination of repetition and
force, and the combination of repetition and cold. A number of good studies demonstrated that there
is also an important role for vibration.
There were nine studies in which carpal tunnel syndrome were defined by a combination of a history of
symptoms and physical examination or nerve conduction testing (Appendix Table 2.5 and Appendix
Table 2.6). In these studies, there were 18 estimates of risk based on various specificities of carpal
tunnel syndrome diagnosis and varying degrees of work exposure. Of these, 12 showed significant
odds ratios greater than 2.0 (range 23-39.8), 4 showed nonsignificant odds ratios of greater than 2.0
and 2 showed nonsignificant odds ratios between 1.7 and 2.0. These findings were supported when
less specific outcomes were examined. In most instances (8 out of 10), conditions classified as “wrist
cumulative trauma disorders” or “nonspecific upper extremity musculoskeletal disorders” were found
to be significantly associated with work-related physical risk factors with a similar range of elevated
/
TABLE 2.3 Summary of Epidemiologic Studies with Risk Estimates of Null and Positive Associations of Specific
Work-Related Physical Exposures and the Occurrence of Upper Extremity Disorders
Risk Estimate
Null Association
a
Positive Association
Attributable Fraction (%)
Work-Related
Risk Factor
n
Range
n
Range
n
Range
Manual material
handling
4
0.90-1.45
24
1.12-3.54
17
11-66
Repetition
4
2.7-3.3
4
2.3-8.8
3
53-71
Force
1
1.8
2
5.2-9.0
1
78
Repetition and
force
0
—
2
15.5-29.1
2
88-93
Repetition and
cold
0
—
1
9.4
1
89
Vibration
6
0.4-2.7
26
2.6-84.5
15
44-95
Notes: n
¼
number of associations presented in epidemiologic studies. Details on studies are presented in Appendix
Table 2.5.
a
Confidence intervals of the risk estimates included the null estimate (1.0).
Source: Reprinted with permission fromNACS (Musculoskeletal Disorders and the workplace. Low Back and Upper Extre-
mities
2001 by the National Academy of Sciences, Courtesy of the National Academics Press, Washington, D.C.)
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