The spine and shoulder are inseparable in terms of coordinated functions in work-related tasks. Maintaining prolonged and abnormal posture of the neck and shoulders is a major cause of CTD. The term cumulative trauma disorder represents repeated microtrauma to specific musculoskeletal tissues over a period of time at a faster rate than the body can heal on its own. If the damage continues to go through the repair process, it will eventually lead to pain, decreased work performance, and loss of function. Jobs that require prolonged elevation of the arms can cause supraspinatus tendinosis due to compression of the humeral head against the coracoacromial arch as the humeral head migrates cranially due to rotator cuff fatigue and sustained stress on the muscle which can inhibit venous circulation. Bicipital tendinosis can result from similar working positions due to repeated friction between the synovial sheath of the tendon (long head) and the lesser tuberosity of the humerus. The physical labor demands that lead to CTD are repetitive movements and maintaining a sustained posture (for example, jobs that require sitting while typing, carpenters, electricians, mechanics, and musicians). Forward head posture is a major risk factor for CTD. Moving the weight of your head forward makes your neck and upper back muscles work harder. This stressful posture can disrupt nerve control and arm circulation. Poor posture is just as much a problem in CTD as repetitive motion is. Jobs that require repetitive movements are often performed in prolonged standing or sitting positions. The posture assumed by the neck and shoulder determines how well the arm, wrist and hand will tolerate the demands of the job. The neck and shoulder are dynamic structures that are movable by design. However, the neck and shoulder are often required to do static work, as the hands perform a specialized task. Maintaining a prolonged working posture of the neck, in association with repetitive movements of a raised shoulder, can restrict circulation to the working tissues of the arm and hand. This situation can be a major obstacle for people trying to return to work after a musculoskeletal injury. Patients with chronic neck and shoulder pain following whiplash in a car accident, for example, have shown a reduced ability to achieve normal increased blood flow to the upper trapezius muscle during progressive workloads. Myofascial disorders of the trapezius, SCM, or infraspinatus muscles can cause reported autonomic phenomena, including vasoconstriction. Jobs that require sustained posture over a long period of time can restrict circulation to active tissues, resulting in premature fatigue and a slower rate of repair of microtraumas in the musculoskeletal system.

Occupational neck and shoulder disorders are usually the result of prolonged flexion or abduction of the shoulders, repetitive arm work, high-speed work, poor head posture,and a maintained static muscle load. A high level of static muscle activity is one reason for the high incidence of neck and shoulder disorders in persons working with cash registers or computer keyboards. Working in a posture with the shoulder flexed or abducted will increase the EMG activity levels in the upper trapezius, cervical, and thoracic erector spinae muscles. One solution is to have the cashier stand rather than sit, which puts less stress on the trapezius, infraspinatus, and thoracic erector spinae muscles. When someone is seated at a desk or table, the forward head posture may be secondary to one or more of the following: a seat height that is too high, a table or visual display terminal height that is too low, or a seat that is too far away from the table.  For computer keyboard operators, ergonomically designed chairs with foot and arm rests are available. The top portion of the visual display terminal should be at eye level. Ergonomic solutions to CTD include the following: correction of both sitting and standing posture ; adjustments to seat, table, and visual display terminal heights, to allow for supportive posture; brief but frequent rest periods throughout the workday; light exercise during breaks to keep the blood flowing freely to all tissues; creation of a balance between repetitive motions of ADLs or sports that simulate job duties and appropriate periods of rest; and training of the worker’s body to become fit—like an athlete—through exercise, nutrition, and rest, to withstand the daily stress on the job.

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