What are work-related musculoskeletal disorders (WMSDs)?
Work-related musculoskeletal disorders are a group of painful disorders of muscles, tendons, and nerves. Carpal tunnel syndrome, tendonitis, thoracic outlet syndrome, and tension neck syndrome are examples.
This page will discuss those injuries resulting from overuse & 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 WMSD affect the hands, wrists, elbows, neck & shoulders. Work using the legs can lead to WMSD of the legs, hips, ankles & feet. Some back problems also result from repetitive activities
What are the risk factors for WMSDs?
WMSDs are caused from arm & hand movements such as bending, straightening, gripping, holding, twisting, clenching & 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. WMSDs 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 WMSD. WMSDs commonly occur as a result of a combination and interaction among them.
Heat, cold and vibration also contribute to the development of WMSD.
WMSDs include three types of injuries:
- Muscle injury
- Tendon injury
- Nerve injury
What are the symptoms of WMSDs?
Pain is the most common symptom associated with WMSDs. In some cases there may be joint stiffness, muscle tightness, redness and swelling of the affected area. Some may also notice sensations of "pins and needles," numbness, skin color changes, & decreased sweating of the hands.
WMSDs 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. The first pain is a signal that the muscles and tendons should rest and recover. Otherwise, an injury can become longstanding,& sometimes, irreversible.
The table below outlines occupational risk factors and symptoms of the most common disorders of the upper body associated with WMSDs.
.
| Identified disorders, occupational risk factors and symptoms |
|---|
| Disorders | Occupational risk factors | Symptoms |
|---|
| Tendonitis/tenosynovitis | Repetitive wrist motions
Repetitive shoulder motions
Sustained hyper extension of arms
Prolonged load on shoulders | Pain, weakness, swelling, burning sensation or dull ache over affected area |
| Epicondylitis (elbow tendonitis) | Repeated or forceful rotation of the forearm and bending of the wrist at the same time | Same symptoms as tendonitis |
| Carpal tunnel syndrome | Repetitive wrist motions | Pain, numbness, tingling, burning sensations, wasting of muscles at base of thumb, dry palm |
| DeQuervain's disease | Repetitive hand twisting and forceful gripping | Pain at the base of thumb |
| Thoracic outlet syndrome | Prolonged shoulder flexion
Extending arms above shoulder height
Carrying loads on the shoulder | Pain, numbness, swelling of the hands |
| Tension neck syndrome | Prolonged restricted posture | Pain |
