Friday, 13 November 2015

Work-Related Musculoskeletal Disorders (WRMSDs)

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.
For the purpose of developing injury prevention strategies, many health and safety agencies include only disorders that develop gradually and are caused by the overuse of the above constituents of the musculoskeletal system. The traumatic injuries of the muscles, tendons and nerves due to accidents are not considered to be WRMSDs or are considered separately. However, there are organizations, such as the European Agency for Safety and Health at Work, that include acute traumas and fractures within in the WRMSD group.
This document will discuss those injuries resulting from overuse and those that develop over time. Work activities which are frequent and repetitive, or activities with awkward postures cause these disorders which may be painful during work or at rest.
Almost all work requires the use of the arms and hands. Therefore, most WRMSD affect the hands, wrists, elbows, neck, and shoulders. Work using the legs can lead to WRMSD of the legs, hips, ankles, and feet. Some back problems also result from repetitive activities.

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.
  • Exercise.
  • 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.

Job Design


One way to eliminate repetitive tasks is to mechanize the job. Where mechanization is not feasible or appropriate, other alternatives are available.

Job Rotation

Job rotation is one possible approach. It requires workers to move between different tasks, at fixed or irregular periods of time. But it must be a rotation where workers do something completely different. Different tasks must engage different muscle groups in order to allow recovery for those already strained.
However, job rotation alone will not be effective in reducing WMSDs if not combined with the proper design of workstations. And it will not be effective while the high pace of work persists.

Job Enlargement and Enrichment

Another approach is job enlargement. This increases the variety of tasks built into the job. It breaks the monotony of the job and avoids overloading one part of the body. Job enrichment involves more autonomy and control for the worker.

Team Work

Team work can provide greater variety and more evenly distributed muscular work. The whole team is involved in the planning and allocation of the work. Each team member carries out a set of operations to complete the whole product, allowing the worker to alternate between tasks, hence, reducing the risk of WRMSDs.

Workplace Design

The guiding principle in workplace design is to fit the workplace to the worker. Evaluation of the workplace can identify the source or sources of WRMSD. Proper design of the workstation decreases the effort required of the worker to maintain a working position. Ideally, the workstation should be fully adjustable, providing a worker with the options to work in standing, sitting or sitting-standing positions, as well as fitting the worker's body size and shape.

Tools and Equipment Design

Proper design of tools and equipment significantly decreases the force needed to complete the task.
Providing the worker with the proper jigs or fixtures for tasks that require holding elements saves a lot of muscular effort in awkward positions.
Good tools, maintained carefully and where necessary frequently changed, can also save a lot of muscle strain

Work Practices

A well-designed job, supported by a well-designed workplace and proper tools, allows the worker to avoid unnecessary motion of the neck, shoulders and upper limbs. However, the actual performance of the tasks depends on individuals.
Training should be provided for workers who are involved in jobs that include repetitive tasks. Workers need to know how to adjust workstations to fit the tasks and their individual needs. Training should also emphasize the importance of rest periods and teach how to take advantage of short periods of time between tasks to relax the muscles, and how to consciously control muscle tension throughout the whole work shift.
Increased communication and support together with an increased ability of the worker to control his job (where possible) are work practices that improve worker’s satisfaction and have a positive impact on reducing the risk of WRMSDs.

Posted by Indian Safety Association

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