Dept. of Biomedical, Industrial, & Human Factors Engineering 1

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 sorenessPeople generally acceptable to these type of problems are:

garment sewing peoplecomputer operatorsmanual packagingbarberscarpentry

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 2

CTDsCauses 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 employeeIndividual 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 3

CTDsForms of CTDs

Bursitis - inflammation of a bursa –padlike sacks found around the jointsTendonitis – inflammation of the tendonsTelephone operator’s elbow – due to resting elbow on hard surface leading to numbnessCarpal-tunnel syndrome - inflamed tendons, tendon sheaths, swelling, etc.

Dept. of Biomedical, Industrial, & Human Factors Engineering 4

Carpal Tunnel SyndromeAffected area