Work Related Musculoskeletal disorders

"Work Related Musculoskeletal disorders" include a wide range of inflammatory and degenerative conditions affecting the muscles, tendons, ligaments, joints, peripheral nerves, and supporting blood vessels and cover a broad range of health problems associated with repetitive and strenuous work. 

 These include clinical syndromes such as tendon inflammations and related conditions (tenosynovitis, epicondylitis, bursitis), nerve compression disorders (carpal tunnel syndrome, sciatica), and osteoarthrosis, as well as less well standardized conditions such as myalgia, low back pain and other regional pain syndromes not attributable to known pathology. Body regions most commonly involved are the low back, neck, shoulder, forearm, and hand, although recently the lower extremity has received more attention.

Work-related MSDs risk factors

The strong correlation between the incidence of MSDs and working conditions is well known, particularly considering the physical risk factors associated with jobs (e.g., awkward postures, high repetition, force exertion, static work, cold or vibration. Work intensification, stress and other psychosocial factors also seem to be factors that increasingly contribute to the onset of those disorders.

The causes of work-related MSDs are multifactorial and there are numerous work-related risk factors for the various types of MSDs. Several risk factors including physical and mechanical factors, organisational and psychosocial factors, and individual and personal factors may contribute to their genesis of MSDs. Τhese injuries developed over time that are caused by a combination of risk factors that act simultaneously on a joint or body region, in a synergistic effect. Until now the biological pathogenesis associated with the development of the majority of the work-related MSDs is unknown. Several models have been proposed to explain the biological mechanisms.

Usually three sets of factors are considered:

  • Physical factors (e.g., sustained or awkward postures, repetition of the same movements, forceful exertions, hand-arm vibration, all-body vibration, mechanical compression, and cold);
  • Psychosocial factors (e.g., work pace, autonomy, monotony, work/rest cycle, task demands, social support from colleagues and management and job uncertainty); and
  • Individual factors (e.g., age, gender, professional activities, sport activities, domestic activities, recreational activities, alcohol/tobacco consumption and, previous work-related MSDs).

Risk factors act simultaneously on a worker joint or body region in a synergistic effect. To manage the risk factors it is advisable and important to take into account this interaction rather than focus on a single risk factor.

How are work postures and movements a risk for WMSDs?

Any body position can cause discomfort and fatigue if it is maintained for long periods of time.  Standing, for example, is a natural body posture, and by itself poses no particular health hazards. However, working for long periods in a standing position can cause sore feet, general muscular fatigue, and low back pain. In addition, improper layout of work areas, and certain tasks can make workers use unnatural standing positions.

Two aspects of body position can contribute to injuries. The first relates to body position. When parts of the body are near the extremes of their range of movements, extreme stretching and compression of tendons and nerves occur. The longer a fixed or awkward body position is used, the more likely we are to develop WMSDs. For example, working with the torso bent forward , backward or twisted can place too much stress on the low back. Other examples of stressful body positions include reaching above shoulder level ,rotating the arms , bending the wrist forward, backward, or side to side .

The second aspect that contributes to WMSDs is holding the neck and the shoulders in a fixed position. To perform any controlled movement with the arm, muscles in the shoulder and the neck contract and stay contracted for as long as the task requires.

The contracted muscles squeeze the blood vessels, which restricts the flow of blood all the way down to the working muscles of the hand.

However, this is where the blood is needed the most because of the intense muscular effort. Two things happen as a result. The neck/shoulder muscles become overtired even though there is little or no movement. At the same time, the reduced blood supply to the rest of the arm accelerates fatigue in the muscles that are moving, making them more prone to injury.

 

Anastasios M. Margaritis
Occupational Health& Safety Specialist.
Bsc Physiotherapy & Sports Science.
Orthopaedic Manual Therapist.
Back Mechanic Specialist.

 


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