Work Related Musculoskeletal Disorders
What Are Work Related Musculoskeletal Disorders (WMSDs)?
When a muscle, tendon, nerve or joint is stressed and traumatized on a repeated basis for days, months or years,
those body tissues eventually become damaged. This leads to a work related musculoskeletal disorder. Work related
musculoskeletal disorders (WMSDs) are sometimes called repetitive strain injuries (RSIs), cumulative trauma disorders
and overuse injuries. When a WMSD develops a worker experiences:
- swelling, as tissues become irritated
- pain
- stiffness and loss of range of motion of surrounding joints
- inability to work and function at home
Figure 1: Body parts where some WMSDs occur.
Table 1: Examples of common WMSDS
| Disease/Condition | Tissue Affected | Symptoms | Possible Causes
|
|---|
Carpal tunnel syndrome occurs on the palm side of the wrist
| Median nerveBlood vesselsTendons
| Numbness/tingling affecting the thumb, index, middle, and half of the ring fingers, especially at night
Weak grip
| Repetitive flexion of wrist
| Myofascial pain in the neck and upper back
| MusclesTendonSometimes nerves
| Heavy feeling, aching painStiffness in upper back and neckPoor sleep
| Working overhead arms in extended position
| Shoulder bursitis
| Bursa (lining of shoulder joint)
| Shoulder painStiffnessProblems putting on sweater
| Repeated shoulder movements
| Rotator cuff tendonitis
| Rotator cuff tendon located in front of shoulder
| Shoulder painStiffnessProblem reaching behind on upper back
| Repeated shoulder movement especially with twisting overhead throwing
| Tennis elbow (lateral epicondylitis)
| Elbow tendon on thumb side of arm
| Elbow painProblem wringing towel and carrying groceries
| Repeated twisting arm movement
| Thumb tendonitis or DeGuervain's tendonitis
| Tendon of thumb (from the nail to the wrist)
| Pain in thumbProblem with pinching and gripping
| Repeated pressing, pulling with thumb
| Trigger fingers or tenosynovitis of fingers
| Tendons, synovium (lining of tendons)
| Fingers "lock" and release by pushing on them
| Repeated use of hand tools or gripping motions
| Wrist/forearm tendonitis
| Tendons, muscle
| Pain, swelling Weak grip
| Repetitive movements of wrists and forearms
|
Besides the most common upper extremity disorders, WMSDs may also affect the low back, knees, ankles and feet.
How Do You Treat WMSDS
Ergonomics should be a priority in the work place, so WMSDs are prevented instead of treated. If you think you
have signs and symptoms of a repetitive strain injury, see your doctor. Make sure your doctor has a description
of your job and understands how your job affects your body.
Treatment may involve a combination of approaches, such as
- Job modifications
- services of health professionals, such as physiotherapists or mas
- sage therapists
- exercise program
- use of medication for pain relief
- application of heat or cold
Your treatment program should be planned by you and your doctor.
What is Ergonomics?
Ergonomics is defined as fitting the task, tools, materials and equipment in the workplace to the worker. The goal
of ergonomics is to reduce the risk of workers developing repetitive strain injuries.
Workers are at risk of injury if they use repetitive, sustained, forceful, or awkward exertions. Other risk factors
are temperature, vibration, gloves, and contact pressure. If two or more risk factors are present, there is a greater
risk of injury. For example, performing a forceful lift once places a worker at less risk of injury than performing a
forceful lift several times per hour. Tables on the following pages identify several ergonomic risk factors and suggest
ways to reduce the risk of injury.
The risk of work related musculoskeletal disorders can be reduced by applying ergonomics principles. Workstation
design, equipment and tools, work environment, and work organization are work components that affect ergonomic risk
factors. An ergonomic design can include such factors as adjustable seating, angled hand tools, or a work pace that can
change to suit the worker.
Figure 2: To fit the job to the worker, you must consider work station design, equipment and tools, work
organization, and work environment.
Using Ergonomics In The Workplace
Does your workplace have any risk factors for repetitive strain injury? Use the following tables to help you identify
some risk factors that may be present in your workplace. Each table also identifies some general recommendations that
may suit you and your workstation. Investigate other ways to reduce ergonomic risk factors at your job.
Table 2: Workstation Design
| Ergonomic Risk Factors | Possible Recommendations
|
|---|
Is your chair uncomfortable?
| If you are required to sit, your chair should be adjustable for height and angle and support your back.
Change positions frequently.
| Do you have to twist or bend?
| Move equipment, parts, and papers closer to you.
Store frequently used equipment and parts slightly above waist height
| Is lifting done above shoulder height?
| Work should be performed below shoulder height. Lower the work piece or use a platform to reduce
working above shoulder height (figure 3).
| Are your elbows raised while you work?
| Work heights should let you work with your elbows close to your body; for example, light assembly work or
typing should be performed at elbow height.
| Is your worktable adjustable?
| If different people share a workstation, some height adjustment is necessary to suit workers of
different heights.
| Do sharp edges put pressure on the skin?
| Round or pad edges of guards, containers or worktables.
| Do workers have pain or discomfort while doing their work?
| Express your concerns to the Joint Health and Safety Committee.
|
Figure 3: Working with the arms above shoulder height increases the risk of developing shoulder injuries. Awkward
postures can be reduced by raising the worker on a platform and/or lowering the work piece.
You can't do it right,
set at the wrong height.
Table 3: Tools
| Ergonomic Concerns | Possible Recommendations
|
|---|
Are the tools heavy?
| Investigate redesigned tools that are lighter. Tool weights can be reduced with overhead tool balancers
or supports.
| Do tools/equipment vibrate?
| Investigate redesigned tools with less vibration. Refer to the OHCOW handout entitled "Hand-Arm Vibration
Syndrome".
| Can anti-vibration gloves reduce vibration exposure?
| Choose anti-vibration gloves that have passed technical testing.
| Are awkward postures required when using tools/equipment?
| Tools can be purchased with bent handles designed to reduce awkward postures.
| Can the force required to use the tool/equipment be reduced?
| Select the right tool size for your hand. A textured tool is easier to grip than a smooth tool.
| Does the tool put pressure on the palm of the hand?
| Tools should have handles that do not end in the palm of the hand.
|
Figure 4: By supporting the weight of the tool and reducing overhead work, the risk of shoulder injury
is reduced.
A workplace at the wrong height
Will make a body sore and tight.
Table 4: Work Organisation
| Ergonomic Concerns | Possible Recommendations
|
|---|
Do you do the same tasks over and over?
| Consider job rotation between jobs involving different movements and muscle groups. Consider
adding a variety of tasks requiring different movements to a repetitive job (job enlargement).
| Is the work pace too fast?
| Reduce the pace of work.
Take breaks that are long enough and frequent enough to allow recovery of overstressed parts.
| Is the training period adequate to educate workers about safe performance of the task?
| Workers should be trained about musculoskeletal injury risk factors.
| Is there a work hardening program?
| Persons returning from absence, work-related injury, or illness require an adjustment period.
| Are workers included in job assessments and design or redesigns?
| Form an Ergonomic Committee made up of worker and employer representatives as a starting point
for reducing musculoskeletal injuries.
|
Table 5: Work Environment
| Ergonomic Concerns | Possible Recommendations
|
|---|
Does poor lighting lead to awkward working postures?
| Light levels that are too dim or too bright can lead to awkward postures. If your light levels
are too bright or too dim, tell your Joint Health and Safety Committee.
| Is it too cold?
| Dress in several layers of clothing. Add and remove clothing as required.
| Is it too Hot?
| Extra rest breaks may be required during times of extreme heat. Water should be readily available.
| Is your work or workplace stressful?
| Workplace stressors like lack of control, feeling overworked, or low levels of job satisfaction
can increase the risk of developing musculoskeletal injuries. Clearly defined roles and
responsibilities and good communication are starting points for reducing stress at work.
| How is the air quality?
| Air quality and ergonomic problems can both lead to health effects like headaches, fatigue, and
muscle soreness.
| Is the workplace noisy?
| Investigate noise reduction methods.
|
Putting Ergonomic Recommendations in Place
If you have answered "yes" to the questions in Tables 2 to 5, there may be ergonomic problems in your
job design. Nobody knows your job and its problems better than you, the worker who performs the job daily.
If you have concerns about your workstation or ideas for improving the workstation design, tools, work
organisation, or work environment, tell your supervisor and Joint Health and Safety Committee representatives.
Ergonomists, occupational hygienists, nurses, and doctors at the Occupational Health Clinics for Ontario
Workers are available to help your Joint Health and Safety Committee solve ergonomic problems.
Useful Readings
1. Canadian Standards Association (CSA) (1989). Office Ergonomics - A National Standard of Canada.
CSA: Rexdale.
2. Eastman Kodak Company (1983). Ergonomic Design for People at Work. (Volume 1). Van Nostrand Reinhold:
New York.
3. Eastman Kodak Company (1986). Ergonomic Design for People at Work. (Volume 2). Van Nostrand Reinhold:
New York.
4. Konz., S. (1995). Work Design. Fourth Edition. Publishing Horizons, Inc.: Scottsdale.
5. London Occupational Safety and Health Information Services (LOSH) (1994). When Aches Become In-juries.
(519) 433-4156
6. Ministry of Labour (1992). Occupational Health and Safety Act. Ministry of Labour: Toronto.
7. Occupational Health Clinics for Ontario Workers (OHCOW) (1997). Office Ergonomics Workbook. OHCOW: Toronto.
(Your nearest OHCOW)
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