Carpal tunnel syndrome – causes and solutions

Part 3 in a Series

In 1997, NIOSH (National Institute for Occupational Safety and Health) released a publication called Musculoskeletal Disorders and Workplace Factors, A Critical Review of Epidemiologic Evidence for Work-Related Musculoskeletal Disorders of the Neck, Upper Extremity, and Low Back http://www.cdc.gov/niosh/docs/97-141/pdfs/97-141.pdf . Although this report over 20 years old, the valuable information about what causes work-related injuries remains current.

One of the most interesting parts of the report is the evidence of work-relatedness to injuries.  From the 40 epidemiologic studies they evaluated, NIOSH judged how strong they felt the evidence was that the injury or musculoskeletal disorder (MSD) was caused by the ergonomic risk factor.   Ergonomic risk factors include:  force, repetition, awkward postures, and static postures to name a few.  The categories they used were:

  • Strong Evidence of Work-Relatedness (+++) – a causal relationship
  • Evidence of Work-Relatedness (++) – convincing epidemiologic evidence for a causal relationship
  • Insufficient Evidence of Work-Relatedness (+/0) – could not conclude the presence or absence of a causal relationship
  • Evidence of No Effect of Work Factors (-) – the specific risk factor is not related to MSDs

What they found for hand/wrist injuries and Carpal Tunnel Syndrome (CTS) was this:

1.  Evidence of Work-Relatedness (++) between highly repetitive work and CTS (repetitive work was defined as activities which involve continuous arm movements which affect the hand and wrist area); between forceful work and CTS (forceful work was defined as powerful wrist or hand movements, which generate loads to hand and wrist area) and between vibration and CTS (vibration primarily from hand tools).  Strong Evidence of Work-Relatedness (+++) between exposure to a combination of risk factors (repetition, force, vibration and posture).

  • Meatpackers, poultry processors, and automobile assembly workers were found to be the most at risk here.
  • Ergonomic tools, rest breaks for warming up, and redesign of tasks with a consideration on automation would all help here in reducing CTS.
2.  Evidence of Work-Relatedness (++) between any single factor (repetition, force, and posture) and hand/wrist tendinitis
  • Industry workers in manufacturing plants for electronics, sewing, and appliances are at a high risk.  Office workers are also at a risk with continuous keyboarding and mousing.
  • Changing the way tasks are completed, job rotation with differing tasks, and proper heights and postures for keyboarding and mousing would all be good ergonomic interventions.
3.  Strong Evidence of Work-Relatedness (+++) between high level exposure to hand-arm vibration and hand-arm vibration syndrome
  • Forestry workers and stone drillers/cutters would have high levels of vibration in their jobs.
  • Tools with lower levels of vibration and vibration-reducing gloves would help here.

I will continue with further body parts in my next post – identifying further jobs where there may be risks and providing guidelines for ergonomic intervention.

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