Ergonomics and Occupational Biomechanics Laboratory
Richard Wells
Epidemiology of Work-Related Musculoskeletal Disorders
Ontario Universities Low Back Pain Study
Epidemiology Reviews
What Musculoskeletal Disorders are Found in the Workplace?

Ontario Universities Low Back Pain Study

There has been considerable debate about the work-relatedness of low-back pain (LBP), North America’s most common occupational health problem. This study was specifically designed to address this debate, with a special interest given to collecting comprehensive workplace exposure data.

Goals:
To to identify work related factors that increased the risk of reporting low back pain (LBP)
To study the relative contribution of physical and psychosocial factors to the reporting of low back pain

More than 350 workers, representing over 250 jobs, participated in the study conducted at Oshawa, one of the largest automotive assembly operations in the world and employing over 10,000 people.

Between 1994 and 1996 the study enrolled 137 people who reported low back pain (cases) and 179 unmatched people chosen at random from the three assembly plants at Oshawa. About one third worked at maintenance, skilled trades and relief work and the remainder worked on short cycle assembly tasks.
[IMAGE]
Gary McCullough, Manager of the Oshawa Car Assembly Plant (centre) joins University of Waterloo researcher Patrik Ingelman and employee Ted Jones during workplace exposure assessment. Taken from: GM TODAY Autumn/ Winter 1995.

Measurement of Workplace Exposure

In-home interviews were used to assess individual (e.g. height, marital status), clinical(e.g. pain, range of motion) and psychosocial (perceptions of the work environment and organization) variables.
The physical demands were assessed by direct workplace measurements on individuals performing their usual job. A wide range of approaches were used to document the physical demands of work including: Questionnaire, Trained Observer, Posture and Load, Sampling, Video Analysis, Postural Analysis, Electromyography (EMG) and Vibration measurement.
All methods were developed specifically for this study and all shared a common metric. This allowed us to estimate loading on the low back for all the methods described.

For example, posture and load variables were obtained from video by a computer assisted tracking system. The video was replayed under computer control and the operator tracked trunk position in three planes using a “video game” joystick. When compared to more accurate methods (OS) the trained operators (OP) could accurately match the motions of the trunk.

Loads on the low back were also estimated from the electrical signals given off by the contraction of the extensor muscles of the spine. These were converted into spinal loads using a calibration process. Workers wore the equipment for an average of four hours.

More details of exposure assessment can be found in Work Assessment


Risk Factors for LBP

The reporting of LBP was found to be a function of both the physical demands of the jobs and a number of worker perceptions.
The significant biomechanical risk factors which independently predicted the reporting of low back pain were:
1) peak hand forces,
2) peak shear force in the low back,
3) cumulative compressive force on the low back over a shift,
4) peak velocity of trunk movement.
Some of the variables were indicators of “peak” (one time highest observed) forces on the low back while others were indicators of “accumulated forces” on the low back.

The significant psychosocial factors which independently predicted the reporting of low back pain were:
1) a high perceived physical load
2) low opinion of the workplace social environment,
3) perception of lack of control of the job,
4) high co-worker support,
5) high job satisfaction,
6) perceived over-education, and
7) a prior WCB claim.

Both physical and psychosocial factors were associated with the reporting of low back pain. Both factors should therefore be addressed in the design and modification of work. These data allow us to identify the probability of reporting LBP for particular levels of exposure. This is potentially usable for establishing job analysis methods and design target values.


Key Papers

Norman, R., Wells, R., Neumann, P*., Frank, J., Shannon, H. and Kerr, M. A Comparison of Peak vs Cumulative Physical Loading Factors for Reported Low Back Pain in the Automobile Industry, Clinical Biomechanics, 13(8): 561-573, 1998.

Kerr, M.S., Frank, S.W., Shannon, H.S., Norman, R.W., Wells, R.P., Neumann, W.P., and Bombardier, C. and the OUBPS group. Biomechanical and psychosocial risk factors for low-back pain at work. American Journal of Public Health, 91:1069-1075, 2001.

Research Team and Support
R. Norman, R. Wells, J. Frank, H. Shannon, M. Kerr, P. Neumann and the members of the Ontario Universities Back Pain Study (OUBPS) working group:
From the Institute for Work and Health: Beaton D.E., Bombardier C, Ferrier S, Hogg-Johnson S, Mondloch M, Peloso P, Smith J, Stansfeld S.A., and Tarasuk V.
From the University of Waterloo: Andrews D.M., Dobbyn M, Edmondstone M.A., Ingelman J.P., Jeans B, McRobbie H, Moore A, Mylett J, Outerbridge G, and Woo H.
This work was funded by the Institute for Work & Health, an independent not-for-profit research organization whose core funding is provided by the Workplace Safety & Insurance Board of Ontario, Canada.
The OUBPS working group would like to thank management at all levels at General Motors of Canada Ltd. for providing access to the study site and work force, the on-site expertise of Mr. Elmer Beddome, the Canadian Auto Workers’ Union for endorsing participation and Mr. John Graham for on-site assistance, the Occupational Health Nurses and all of the GM medical staff. We extend a special thanks to the many employees who donated considerable non-work time and volunteered to have their work monitored in this study.
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Epidemiology Reviews

I was involved in a project with the Provincial Government of Quebec (IRSST) and National Research Council (NRC) to participate in a review the field of Work-Related Musculoskeletal Disorders. This was one of the first attempts to survey, analyse and summarize the findings on this condition variously called repetitive strain injuries(RSI) or cumulative trauma disorders (CTD) The reference book below is a product of that project.

Hagberg, M., Silverstein, B., Wells, R., Smith, R., Carayon, P., Hendrick, H., Perusse, M., and Kourinka, I. and Forcier, L. (eds). Work-related Musculoskeletal Disorders (WMSD): A Handbook for Prevention, Taylor and Francis, London, 1995.

Since then, there have been two more major reviews:
NRC and IOM (2001). Musculoskeletal disorders and the workplace: low back and upper extremities. Washington, DC, National Academy Press.

Bernard BP. (1997) Musculoskeletal disorders (MSDs) and workplace factors: a critical review of epidemiologic evidence for work-related musculoskeletal disorders of the neck, upper extremity, and low back. US Department of Health and Human Services, National Institute of Occupational Safety and Health USA 1997.

A more focussed review of low back pain can be found in:

Frank, J., Brooker, A-S., DeMaio, S., Kerr, M., Maetzel, A., Shannon, H., Sullivan, T., Norman, R., and Wells, R. Disability Due to Occupational Low Back Pain: What do we Know About Primary Prevention? Spine, 1996, 21(24):2908-2917.

Frank, J., Brooker, A-S., DeMaio, S., Kerr, M., Maetzel, A., Shannon, H., Sullivan, T., Norman, R., and Wells, R. Disability Due to Occupational Low Back Pain: What do we Know About Secondary Prevention? Spine, 1996, 21(24):2918-2929.
What Musculoskeletal Disorders are Found in the Workplace?
Musculoskeletal Disorders in Industry

Ranney, D., Wells, R., and Moore, A.* The Anatomical Location Of Work-related Chronic Musculoskeletal Disorders in Selected Industries Characterized by Repetitive Upper Limb Activity. Ergonomics, 1995, 38(7):1408-23.


Musculoskeletal Disorders in the Office

Polanyi, M*., Cole, D., Beaton, D., Chung, J*., Wells, R., Abdolell, M., Beech-Hawley, L*., Ferrier, S., Mondlock, M.., Sheilds, S., Smith. J. and Shannon, H. Upper-limb Work Related Musculoskeletal Disorders Among Newspaper Employees: Cross-sectional Survey Results. American Journal of Industrial Medicine, (32):620-628, 1997.

Beech-Hawley L, Wells R, Cole DC and the Worksite Upper Extremity Group. The experience sampling method: an approach to the study of deadlines in newspaper workers, Work, 2004


Low Back Pain and Disability in the Workplace

Norman, R., Wells, R., Neumann, P., Frank, J., Shannon, H. and Kerr, M. A Comparison of Peak vs Cumulative Physical Loading Factors for Reported Low Back Pain in the Automobile Industry, Clinical Biomechanics, 13(8): 561-573, 1998.


Kerr, M.S., Frank, S.W., Shannon, H.S., Norman, R.W., Wells, R.P., Neumann, W.P., and Bombardier, C. and the OUBPS group. Biomechanical and psychosocial risk factors for low-back pain at work. American Journal of Public Health, 91:1069-1075, 2001.

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Copyright © 2007 Richard Wells,
Ergonomics and Occupational Biomechanics Laboratory
This page last updated January, 2007