Musculoskletal Disorders Musculoskletal Disorders

(MSDs) (MSDs) Reference: http://www.cdc.gov/niosh/ergtxt1.htmlReference: http://www.cdc.gov/niosh/ergtxt1.html Accident - An unplanned event which has

the potential to disrupt normal safe operations; results in:

a fatality, injury, occupational illness, uncontrolled discharge to the environment, or any other Occupational Health and Safety non-compliance.

• Injury A particular form of damage or harm done to or suffered by a person or thing; e.g. sprains, strains, wounds, back pain, bleeding…

• Accidental injury

A bodily injury caused solely by external, traumatic, and unforeseen means.

Hazard:

a hazard exists where an object (or substance) or situation has a built-in ability to cause injury, harm, or ill health; e.g. uneven pavement, unguarded machine, icy road, fire, dangerous animals, toxic waste.

Risk: The chance that harm will actually occur. The presence of potential target (e.g. person) and his distance from the hazard will determine the extent of the risk. It ranges from severe to negligible.

Hazard & RiskFor instance, a fire or explosion may cause

damage to nearby buildings and their contents, or to vehicles and equipment, but will not harm people if there are no people present at the time.

Risk factor: a substance or situation or characteristic that may increase the chance of developing a disease; e.g. gender, age, occupation are risk factors for MSDs disorders

• Epidemiology of injuries

• Epidemiological triangle

Host

Agent Environment

• Agent: The several forms of injury • Physical : Mechanical, thermal, solar,

radiation.– Chemical

• Environment: • - physical.• - Sociocultural

• Injuries are like infectious diseases cannot occur without the action of an agent and likewise transmitted by a vehicle or vector.

• The distribution and magnitude of injury is determined by the interaction of the triad.

Work-related MSDsWork-related MSDs

MSDs are injuries or disorders of the muscles, nerves, tendons, joints, cartilage, and spinal discs.

MSDs include sprains, strains, tears;back pain,; soreness, pain, hurt, other than back;carpal tunnel syndrome (CTS); andmusculoskeletal system and

connective tissue diseases and disorders

Causes of MSDsMSDs occur when the event or exposure leading to the case is due to:

1. Body reaction (bending, climbing, crawling, reaching, twisting),

2. Overexertion/forceful work (pushing, pulling, holding, lifting, carrying)

3. Repetitive motion (cyclical flexion-extension, abduction-adduction, pronation-supination…)

4. Vibration5. Awkward posture.

Epidemiological evidence of work-related MSDs

• Low Back disorders

• - Heavy physical work +• - Lifting/forceful movement +++• - Bending/twisting +++• - Whole body vibration +++

• Elbow MSDs (Epicondylitis)

• Repetitive work +• Forceful work

+• Awkward posture +• Forceful & repetitive work +

+• Forceful work & posture +

+

• Repetition defined : cyclical flexion and extension of elbow or pronation-supination of wrist joint.

• Forceful work: Strenuous work involving forearm extensors or flexors.

Hand/wrist MSDs (Carpel Tunnel Syndrome CTS)

• - Repetitive work +• - Forceful work +• - Awkward posture +• - Vibration +• - Combination of two or more

Of the above +++

• N.B.: + indicates no evidence + indicates existing of

evidence++ indicates existing of

strong evidence+++ indicates existing of very strong evidence

(almost causal relationship)

• Social & demographic Distribution of MSDs

• Variable %• Age

<25 11.825-34 25.935-44 31.245-54 21.8>55 9.3

• Sex %• Males 62.5• Females 37.5• Severity (measured by lost days from

work)Days %1-2 23.53-5 19.96-10 13.511-20 12.321-30 6.930+ 23.9

Epidemiology ofLow Back Pain

Prevalence:70–85% of all people have back pain at some time in life. The annual prevalence of back pain ranges from 15% to 45%, with point prevalences averaging 30%.In the USA, back pain is:

the most common cause of activity limitation in people youngerthan 45 years, the second most frequent reason for visits to the physician, the fifth-ranking cause of admission to hospital, and the third most common cause of surgical procedures

UK estimates place low-back pain as: the largest single cause of absence from work, and it is responsible for about 12·5% of all sick days

Source: THE LANCET vol 354, August 1999, 581

Chronic Back Pain Definition:

defined as back pain that lasts for longer than 7–12 weeks.

Others define it as pain that lasts beyond the expected period of healing.

Prevalence: • the most prevalent impairment in people aged up to 65 years. • More common in women (70·3 per 1000 population) than in men (57·3• per 1000 population), and • more common among white people (68·7 per 1000 people) than black

people (38·7per 1000 people).

Recovery from back pain• Most patients with back pain recover quickly and without residual

functional loss. • There are similarities in recovery rates between studies and countries. • Overall, 60–70% recover by 6 weeks, 80–90% by 12 week

factors affecting recovery:

1. Diagnosis (with/out sciatica)

2. On-duty/off-duty injuries

3. Psychological disturbances

Recurrence

The recurrence rate of low-back pain is so high. Lifetime recurrences of up to 85% were reported. In Sweden, the 1-year recurrence of sick-listing for low-backpain was 44%. Data from Canada show recurrence rates of 20% in 1 year and 36% over 3

years.

Factors affecting rates of recurrence Men had a higher risk of recurrence than women, and people aged 25–44 years had the highest rate of recurrence. Occupation also affected the rate of recurrence, the highest rate

occurred in nurses anddrivers and the lowest among white-collar workers.

Office visits to physicians

There were about 15 million office visits to physicians in the USA for mechanical low-back pain annually, accounting for about 2·8% of all office visits.

The annual rate of consultations with these patients in the UK has been estimated at 5·5–7·5% of the adult population.

Swedish estimates for the number of outpatient visits for back pain are 790,000 people or 8·9 per 100 person-years.

Rates of hospital admission and surgery

Rates of surgery for back pain have increased rapidly over the past

15 years, whereas rates of non-surgical hospital admission

have decreased.

There are substantial variations between countries in

rates of back surgery.

Cherkin and colleagues found that in the USA, the rate is at least 40% higher than in any other country, and more than five times higher than in Scotland and England.

Differences are more likely explanations are cultural differences, differences in practice patterns, and the availability of health-care providers.

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