Work-related Musculoskeletal Disorders of the Neck, Back, and Upper Extremity in Washington State, 1990-1998

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Washington State Department of Labor and Industries , Safety and Health Assessment Research for Prevention (SHARP) Program

Summary Statement

An in-depth research study of work-related musculoskeletal disorders in Washington state from 1990-1998 based on worker’s compensation claims.
May 2000

This study uses workers’ compensation claims data from Washington State to examine the frequency, incidence, cost, and industry distribution of new neck, back and upper extremity (hand/wrist, elbow, and shoulder) disorders, and respectively sciatica, carpal tunnel syndrome (CTS), epicondylitis and rotator cuff syndrome (RCS) as examples of more specific diagnoses within these body region categories.


Incidence rate: number of new cases per 10,000 full-time equivalent (FTE) workers per year.

Relative risk: Incidence rate of specific industry divided by incidence rate for all industries. Relative risk of more than 1 indicates risk in that industry is more than for all industries combined.

WIC: Washington Industrial Classification equals the 4-digit “Risk Class” in the State Fund.

Sciatic pain is manifested as radiating back pain that goes below the knee. This very sensitive (95%) indicator of lumbar disc herniation i has been associated with manually handling heavy loads.

Carpal tunnel syndrome (CTS) is the compression of the median nerve at the wrist, due to ischemia or inflammation. CTS is characterized by numbness, tingling, or pain in the median nerve distribution of the hand (first 3 1/2 fingers), frequently with nocturnal worsening of symptoms. Work-related CTS has been associated with high repetition, force, awkward wrist postures and segmental vibration ii iii .

Epicondylitis is an inflammation of the tendon at the elbow (lateral epicondylitis or tennis elbow is most common). Epicondylitis is characterized by pain during resisted maneuvers that load the tendons and by tenderness on tendon palpation. Repetitive forceful postures such as twisting or pronation of the forearm combined with extension of the wrist while gripping have been associated with epicondylitis.

Rotator cuff syndrome involves inflammation, degeneration and tear of the tendons about the shoulder (with the supraspinatus tendon most frequently involved). Pain with certain motions is common, particularly against resistance. Tearing usually results in weakness. Work-related shoulder disorders have generally been attributed to high static or repetitive loads on the shoulder girdle, particularly in combination with abduction, rotation or flexion iv .

Each of these specific conditions has also been associated with an acute traumatic onset (e.g., falls).

The objectives in this study were to estimate the overall and yearly trends in claim incidence rates, costs and days lost from work over the period 1990-1998, for general and specific work-related musculoskeletal disorders. Additionally, we wanted to identify high-risk industries for these disorders so both research and prevention efforts can be more focused.