Although previous studies have related occupational exposure and epicondylitis, the evidence is moderate, and mostly based on cross-sectional studies. Suspected physical exposures were tested over a three year period in a large longitudinal cohort study of workers in the United States.
In a population-based study including a variety of industries, 1107 newly employed workers were examined; only workers without elbow symptoms at baseline were included. Baseline questionnaires collected information on personal characteristics and self-reported physical work exposures and psychosocial measures for the current or most recent job at 6 months. Epicondylitis (lateral and medial) was the main outcome, assessed at 36 months based on symptoms and physical examination (palpation or provocation test). Logistic models included the most relevant associated variables.
Of 699 workers tested after 36 months who did not have elbow symptoms at baseline, 48 suffered from medial or lateral epicondylitis (6.9%), with 34 cases of lateral epicondylitis (4.9%), 30 cases of medial epicondylitis (4.3%), and 16 workers who had both. After adjusting for age, lack of social support, and obesity, consistent associations were observed between self-reported wrist bending/twisting and forearm twisting/rotating/screwing motion and future cases of medial or lateral epicondylitis (odds ratios 2.8 [1.2;6.2] and 3.6 [1.2;11.0] respectively in men and women).
Self-reported physical exposures that implicate repetitive and extensive/prolonged wrist bend/twisting and forearm movements were associated with incident cases of lateral and medial epicondylitis in a large longitudinal study, although other studies are needed to better specify the exposures involved.
Epicondylitis (medial and lateral) is one of the most common musculoskeletal disorders of the upper extremity.[
We enrolled a cohort of 1107 newly employed workers in St. Louis, USA, between July 2004 and October 2006.[
Baseline questionnaires collected information on personal characteristics, age, gender, body mass index (obese, ≥30kg/m2), educational level, and prior history of arthritis. Questions also included elbow and forearm symptoms occurring more than 3 times or lasting more than one week in the past year. Prior history of elbow pain or other musculoskeletal disorders was not collected.
Self-reported workplace psychosocial measures and the duration of eight physical exposures were collected for the current or most recent job at several time points. Exposures relevant to epicondylitis included “bending” (On average, how long altogether each day did you frequently bend or twist your hands or wrists?) “rotating” (On average, how long altogether each day did you do tasks where there was a rotating, twisting or screwing motion of the forearm?), and “gripping” (On average, how long altogether each day did you use your hand in a forceful grip?). We categorized responses into four categories (none or less than 1 hour/day, 1-2 hours/day, 2-4 hours/day, ≥4hours/day). Based on results of univariate analyses, we chose the most relevant cut points for dichotomizing exposures. A social support scale measurement less than or equal to 22 was chosen as threshold, representing the lowest quartile of social support. At the baseline examination, most workers had just started their new jobs. We thus used the physical and psychosocial measures reported after six months at work, thinking that these reports would better represent typical job conditions.
Medial and lateral epicondylitis were assessed with a questionnaire and physical examination 3-5 years after baseline exam. Our case definition of epicondylitis required symptoms of recurrent or persistent elbow pain in the past year and positive physical examination in the same arm. Subjects who reported elbow or forearm pain at baseline were excluded from further analysis. The physical examination was considered positive if the subject reported pain or discomfort when the examiner palpated the medial or lateral epicondyles, muscle insertions, or surrounding musculature, or if the subject reported pain or discomfort at the elbow on resisted extension or flexion of the wrist (the examiner applied resistance against the hand with the elbow in 30° of flexion). We evaluated both arms of each subject and reported cases at the level of the person.
We performed logistic regression to test the association of demographic and work-related factors with lateral and medial epicondylitis, considered separately and as a composite outcome. We combined men and women in initial models, and also evaluated them separately. We performed sensitivity analysis with a model containing only those subjects who did not change jobs during the study period.
Statistical Analysis Software (SAS v9.3, SAS institute Inc, Cary, NC, USA) was used for all analyses. Associations were expressed as odds ratios and 95% confidence intervals.
Of the 1107 subjects recruited, 76 reported elbow or forearm pain at baseline; after excluding these subjects, 699 (67.8%) completed follow-up testing with physical examination and questionnaire. The median follow-up time was 34 months from baseline (range 26 to 71 months). Loss to follow-up was more common among workers with a high school diploma or less education at baseline, compared to those with some education beyond high school (n=194, 58.4% of those lost to follow-up vs. n=336, 48.7% in the group who were followed up, P<0.05). No other differences in variables of interest were found between those who completed follow-up and those lost to follow-up. At follow-up, 34 subjects had lateral epicondylitis (4.9%), 30 subjects had medial epicondylitis (4.3%), 48 had either medial or lateral epicondylitis (6.9%) and 16 had both.
Univariate analysis of the composite variable of incident epicondylitis found associations with bending, rotating, and forceful gripping, with risk increasing at higher reported durations of these exposures (
When we focused on only subjects who had not changed jobs in the three-year period for sensitivity analyses (n=467, 66.8%), we found a similar magnitude of association between bending/rotating and epicondylitis (odds ratio 3.4, 95% c.i. 0.9-12.3).
We found that self-reported physical exposures of wrist bending and forearm rotation were associated with incident medial and lateral epicondylitis after three years of follow-up in a longitudinal cohort study of workers in a variety of jobs.
Our study had several limitations. Subjects did not receive serial physical examinations during the study, but only a single follow-up examination. While the frequency of epicondylitis (6.9%) in our study was comparable to that in other studies of working populations,[
Strengths of the study include its prospective nature, a large and varied cohort, and a case definition requiring both symptoms and physical signs. Physical exposures were self-reported more than two years before the assessment of case definition, limiting opportunities for biased reporting of exposures due to symptoms. Despite their modest to low agreement with observed exposures,[
Wrist bending/twisting and forearm rotating, twisting, or screwing motion were associated with incident cases of both lateral and medial epicondylitis in our study. Previous cross-sectional studies have found associations between epicondylitis and work exposures, including hard perceived physical exertion combined with elbow flexion/extension (>2 hr/day) and wrist bending (>2 hr/day),[
In conclusion, self-reported physical exposures involving repetitive and extensive movements of the wrist and forearm were associated with future cases of medial and lateral epicondylitis in a three-year prospective longitudinal study. Although additional studies are needed to better define the specific work exposures (including gripping) and personal factors (such as obesity) related to medial and lateral epicondylitis, self-reported work exposures predicted future risk in our study, and may be useful in workplace preventive efforts for this relatively common disorder.
study performed at this institution
- Many cross sectional studies have established that medial and lateral epicondylitis are associated with physically forceful occupational activities, especially high force combined with high repetition or awkward posture
- At three-year follow-up among workers without elbow symptoms at baseline, 48 suffered from medial or lateral epicondylitis (6.9%)
- Self-reported physical exposures were associated with subsequent incident cases of lateral and medial epicondylitis in this large longitudinal study
Univariate and multivariate associations between personal and work-related risk factors and epicondylitis
| Lateral epiconylitis n=34 | Medial epiconylitis n=30 | Lateral | Lateral or Medial | Lateral or Medial | |||||||||||
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| N | n | % | Odds ratio | Odds ratio | n | % | Odds ratio | Odds ratio | n | % | Odds ratio | Odds ratio | Odds ratio | Odds ratio | |
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| 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.1 | |||||||
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| Men | 449 | 20 | 4.5 | 1 | 1 | 18 | 4.0 | 1 | 1 | 31 | 6.9 | 1 | 1 | ||
| Women | 250 | 14 | 5.6 | 1.3 | 1.1 | 1.2 | 1.3 | 17 | 6.8 | 1.0 | 0.9 | ||||
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| > high school | 363 | 13 | 3.6 | 1 | 1 | 7 | 1.9 | 1 | 1 | 17 | 4.7 | 1 | 1 | ||
| ≤High school education | 336 | 21 | 6.3 | 1.8 | 1.87 | 23 | 6.9 |
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| 31 | 9.3 |
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| 1.9 | 2.5 |
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| No | 512 | 23 | 4.5 | 1 | 1 | 22 | 4.3 | 1 | 1 | 35 | 6.8 | 1 | 1 | 1 | 1 |
| Yes | 122 | 7 | 5.7 | 1.3 | 1.0 | 7 | 5.7 | 1.4 | 1.1 | 9 | 7.4 | 1.1 | 0.9 | 0.5 | 2.3 |
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| No | 666 | 30 | 4.5 | 1 | 1 | 26 | 3.9 | 1 | 1 | 44 | 6.6 | 1 | 1 | 1 | 1 |
| Yes | 33 | 4 | 12.1 | 2.9 | 2.0 | 4 | 12.1 |
| 3.3 | 4 | 12.1 | 2.0 | 1.7 | 0.9 | 2.9 |
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| <30 kg/m2 | 468 | 16 | 3.4 | 1 | 1 | 18 | 3.9 | 1 | 1 | 27 | 5.8 | 1 | 1 | 1 | 1 |
| ≥30 kg/m2 | 231 | 18 | 7.8 |
| 1.8 | 12 | 5.3 | 1.4 | 1.0 | 21 | 9.1 | 1.6 | 1.3 | 1.5 | 0.9 |
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| No or <1 hour/day | 227 | 4 | 1.8 | 1 | 0 | 0.00 | 1 | 4 | 1.8 | 1 | |||||
| 1-2 hours/day | 70 | 1 | 1.4 | 0.8 | 3 | 4.3 | 1 | 3 | 4.3 | 2.5 | |||||
| 2-4 hours/day | 106 | 5 | 4.7 | 2.8 | 5 | 4.7 |
| 7 | 6.6 |
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| ≥ 4hours/day | 272 | 20 | 7.4 |
| 1 | 7.8 |
| 30 | 11.0 |
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| No or <1 hour/day | 371 | 11 | 3 | 1 | 11 | 3.0 | 1 | 16 | 4.3 | 1 | |||||
| 1-2 hours/day | 68 | 2 | 2.9 | 1.0 | 1 | 1.5 | 0.5 | 3 | 4.4 | 1.0 | |||||
| 2-4 hours/day | 77 | 5 | 6.5 | 2.3 | 6 | 7.8 | 2.8 | 8 | 10.4 | 2.6 | |||||
| ≥ 4hours/day | 159 | 12 | 7.6 |
| 11 | 7.0 |
| 17 | 10.7 |
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| No or <1 hour/day | 312 | 11 | 3.5 | 1 | 7 | 2.2 | 1 | 13 | 4.2 | 1 | |||||
| 1-2 hours/day | 89 | 4 | 4.5 | 1,3 | 4 | 4.5 | 2.1 | 6 | 6.7 | 1.7 | |||||
| 2-4 hours/day | 99 | 5 | 5.1 | 1.5 | 4 | 4.1 | 1.9 | 6 | 6.1 | 1.5 | |||||
| ≥ 4hours/day | 175 | 10 | 5.7 | 1.7 | 14 | 8.0 |
| 19 | 10.9 |
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| No | 512 | 16 | 3.1 | 1 | 1 | 14 | 2.7 | 1 | 1 | 22 | 4.3 | 1 | 1 | 1 | 1 |
| Yes | 163 | 14 | 8.6 |
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| 15 | 9.3 |
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| 22 | 13.5 |
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Medical Disorders = diabetes, rheumatic arthritis or osteoarthrosis;
because no worker with medial epicondlytis reported less than 1 hour of bending, reference included also 1-2 hours/day;