Workers who often use their hands in forceful gripping and pinching motions face a higher risk of developing carpal tunnel syndrome (CTS), a painful condition that causes tingling, numbness and weakness in the hand and sometimes requires surgery.
Low-force repetitive hand motion and wrist posture, widely thought of as key risk factors, appear to be of lower importance than forceful pinching and gripping among workers doing hand-intensive tasks such as food processing and manufacturing work, said Dr. Bradley Evanoff, Richard A. and Elizabeth Henby Sutter Professor of Occupational and Environmental Medicine at the Washington University School of Medicine in St. Louis. He was delivering keynote remarks at the 9th International Scientific Conference on the Prevention of Work-Related Disorders, hosted by the Institute for Work & Health (IWH) in Toronto June 20 through 23, 2016.
Evanoff shared findings from the U.S. National Institute for Occupational Safety and Health (NIOSH) Upper Limb Consortium project, which draws on data from more than 4,300 workers in over 50 workplaces to explore the role of both personal and work factors associated with CTS. The consortium studies showed:
- sex/gender is a risk factor, with women at 30 per cent greater risk of developing CTS than men;
- age and body mass index are both risk factors, with the risk of CTS rising with each increase in age range up to 55 (the upper limit of the data available) and with each increase in BMI; and
- co-morbid conditions such as diabetes, rheumatoid arthritis and thyroid conditions do not increase the risk of CTS.
Evanoff also shared the following findings with respect to workplace factors:
- forceful hand exertion is a CTS risk factor;
- wrist posture alone is not a risk factor;
- hand repetition is a risk factor only when force is involved (hand repetition alone is not a risk factor);
- some psychosocial factors such as decision latitude and social support have a protective effect; and
- current thresholds for hand force and repetition recommended by the American Conference for Governmental Industrial Hygienists (ACGIH) are insufficiently protective.
Evanoff emphasized that the consortium project cannot speak to the role of a number of work-related factors because of lack of information, including vibration, task variability and extreme wrist extesion or flexion for long periods.