What are work-related musculoskeletal disorders (WRMSDs)?
Work-related musculoskeletal disorders (WRMSDs) are a group of painful disorders of muscles, tendons, and nerves. Carpal tunnel syndrome, tendonitis, thoracic outlet syndrome, and tension neck syndrome are examples.
Are there other names for WRMSDs?
WMSDs are very difficult to define within traditional disease classifications. These disorders have received many names, such as:
- Repetitive motion injuries.
- Repetitive strain injuries.
- Cumulative trauma disorders.
- Occupational cervicobrachial disorders.
- Overuse syndrome.
- Regional musculoskeletal disorders.
- Soft tissue disorders.
Most of the names do not accurately describe the disorders. For example, the term "repetitive strain injuries" suggests that repetition causes these disorders, but awkward postures also contribute. These terms are used synonymously. In the absence of an agreement, WRMSD term is used in this document.
What are the risk factors for WRMSDs?
WRMSDs arise from arm and hand movements such as bending, straightening, gripping, and holding, twisting, clenching and reaching. These common movements are not particularly harmful in the ordinary activities of daily life. What makes them hazardous in work situations is the continual repetition, often in a forceful manner, and most of all, the speed of the movements and the lack of time for recovery between them. WRMSDs are associated with work patterns that include:
- Fixed or constrained body positions.
- Continual repetition of movements.
- Force concentrated on small parts of the body, such as the hand or wrist.
- A pace of work that does not allow sufficient recovery between movements.
Generally, none of these factors acts separately to cause WRMSD. WRMSDs commonly occur as a result of a combination and interaction among them.
Heat, cold and vibration also contribute to the development of WRMSD.
How do WRMSDs occur?
WRMSDs that develop gradually as a result of repeated trauma.
WRMSDs include three types of injuries:
- Muscle injury.
- Tendon injury.
- Nerve injury.
What are the symptoms of WRMSDs?
Pain is the most common symptom associated with WRMSDs. In some cases there may be joint stiffness, muscle tightness, redness and swelling of the affected area. Some workers may also experience sensations of "pins and needles," numbness, skin colour changes, and decreased sweating of the hands.
WRMSDs may progress in stages from mild to severe.
Early stage: Aching and tiredness of the affected limb occur during the work shift but disappear at night and during days off work. No reduction of work performance.
Intermediate stage: Aching and tiredness occur early in the work shift and persist at night. Reduced capacity for repetitive work.
Late stage: Aching, fatigue, and weakness persist at rest. Inability to sleep and to perform light duties.
Not everyone goes through these stages in the same way. In fact, it may be difficult to say exactly when one stage ends and the next begins. The first pain is a signal that the muscles and tendons should rest and recover. Otherwise, an injury can become longstanding, and sometimes, irreversible. The earlier people recognize symptoms, the quicker they should respond to them.
How are WRMSDs recognized?
The evaluation of WRMSDs includes identifying workplace risks. Evaluation begins with a discussion of the person's employment and requires a detailed description of all the processes involved in a typical workday. Consideration is given to the frequency, intensity, duration, and regularity of each task performed at work.
Diagnosis of WRMSDs is confirmed by performing laboratory and electronic tests that determine nerve or muscle damage. One such test, electroneuromyography (ENMG), encompasses two areas: electromyography (EMG) and nerve conduction velocity (NCV). Magnetic resonance imaging (MRI), an alternative to x-rays, provides images of tendons, ligaments, and muscles and improves the quality of the diagnostic information.
How are WRMSDs treated?
The treatment of WRMSDs involves several approaches including the following:
- Restriction of movement.
- Application of heat or cold.
- Medication and surgery.
How can we prevent WRMSDs?
Hazards are best eliminated at the source; this is a fundamental principle of occupational health and safety. In the case of WRMSDs, the prime source of hazard is the repetitiveness of work. Other components of work such as the applied force, fixed body positions, and the pace of work are also contributing factors. Therefore the main effort to protect workers from WRMSDs should focus on avoiding repetitive patterns of work through job design which may include mechanization, job rotation, job enlargement and enrichment or teamwork. Where elimination of the repetitive patterns of work is not possible or practical, prevention strategies involving workplace layout, tool and equipment design, and work practices should be considered.