Download HFE 307 Lecture 7

Cumulative Trauma Disorders (CTDs)
Cumulative Trauma Disorders – disorders of the softer tissue
due primarily to repeated use. Typically in the upper extremities
and can range from joint inflammation to muscle soreness
People generally acceptable to these type of problems are:
garment sewing people
computer operators
manual packaging
barbers
carpentry
Human hand composed of tendons, ligaments, nerves, etc.
flexor tendons pass through a tight tunnel called the carpal tunnel
Dept. of Biomedical, Industrial, & Human Factors Engineering
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CTDs
Causes and Prevention Techniques
Unnatural joint posture – any time a joint assumes an unnatural position CTD risk
is increased. See Figure 3.19.
Forceful application – application of force to hinge joints (e.g., wrist) increases
injury potential. Pivot joints (elbow) are at a lesser risk. Some evidence suggests
that exceeding one-third of workers static muscle strength maybe a causative factor.
Repetition of activity – highly repetitive tasks (less than 30 seconds) pose more risk
to the employee
Individual factors – preexisting conditions aggravate conditions such as neuropathy,
arthritis, small hand/wrist.
Other – localized pressure and exposure to vibration and cold over time may cause
CTDs.
Prevention techniques include administrative and engineering controls (automation,
job and workplace design, tool redesign, and work/rest cycles)
Therapeutic approaches include rest, immobility, vitamins, anti-inflammatory drugs
and even surgery.
Dept. of Biomedical, Industrial, & Human Factors Engineering
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CTDs
Forms of CTDs
Bursitis - inflammation of a bursa –padlike sacks found around the
joints
Tendonitis – inflammation of the tendons
Telephone operator’s elbow – due to resting elbow on hard surface
leading to numbness
Carpal-tunnel syndrome - inflamed tendons, tendon sheaths,
swelling, etc.
Dept. of Biomedical, Industrial, & Human Factors Engineering
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Carpal Tunnel Syndrome
Affected area
Dept. of Biomedical, Industrial, & Human Factors Engineering
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