What occupational factors are linked to the development of shoulder osteoarthritis?

Occupational Factors Linked to Shoulder Osteoarthritis

The strongest evidence indicates that occupational mechanical exposures—particularly heavy lifting, overhead work, forceful activities, and combined mechanical demands—increase the risk of developing shoulder osteoarthritis, especially in the acromioclavicular joint. 1

Primary Risk Factors with Established Evidence

Heavy Lifting and Force

• Lifting weights ≥10 pounds with high frequency demonstrates the clearest association with shoulder OA development. 2
• Work requiring lifting or moving >10 pounds often or always shows significantly higher odds of shoulder symptoms and disability. 2
• For heavy lifting specifically, odds ratios range from 1.3 to 10.3 in the highest exposure groups, with exposure-response relationships documented for acromioclavicular OA. 1
• The evidence is particularly strong when lifting is combined with other mechanical stresses rather than occurring in isolation. 3

Overhead Work and Upper Arm Elevation

• Overhead working represents a well-documented risk factor for shoulder disorders, with odds ratios ranging from 0.5 to 2.2 for upper arm elevation in the highest exposure categories. 1
• Exposure-response relationships exist between upper arm elevation and acromioclavicular OA development. 1
• Working in awkward postures, particularly with arms elevated, increases shoulder disorder risk when combined with other physical demands. 3

Combined Mechanical Exposures

• Combined mechanical exposures show the strongest associations, with odds ratios of 2.2 to 2.9 for shoulder OA. 1
• Physically demanding occupations requiring combinations of overhead work, heavy lifting, forceful work, and awkward postures demonstrate the highest risk. 3
• The service industry shows particularly elevated odds for both shoulder symptoms and upper extremity disability compared to managerial/professional occupations. 2

Vibration Exposure

• Whole-body and hand-arm vibration exposure shows odds ratios ranging from 1.7 to 3.1 in the highest exposure groups for acromioclavicular OA. 1
• Exposure-response relationships are documented between vibration and AC joint osteoarthritis. 1

Repetitive Tasks

• Repetitive manual tasks involving tool use and fine motor manipulation over extended periods contribute to shoulder OA risk, with an odds ratio of 2.4 in exposed groups. 1
• Exposure-response relationships exist between repetitive work and acromioclavicular OA. 1

Heavy Work While Standing

• Work requiring heavy physical demands while standing shows associations with shoulder symptoms, with stronger effects observed among men and White workers. 2

Joint-Specific Considerations

A critical distinction exists between acromioclavicular (AC) joint and glenohumeral joint osteoarthritis:

• All occupational mechanical exposures demonstrate exposure-response relationships specifically for AC joint OA. 1
• The evidence base is substantially weaker for glenohumeral OA, suggesting occupational factors may preferentially affect the AC joint. 1
• Prevalence estimates in exposed occupational groups range from 2.9% to 61.8% depending on the specific job and joint assessed. 1

Duration and Dose-Response Relationships

• Long-term exposure (typically ≥20 years) to mechanical stresses represents the highest risk category across multiple occupational activities. 4
• Cumulative loads exceeding 37,000 kg × hours over a career establish dose-response relationships for OA development. 4
• Mechanical and occupational stress likely plays a role in the articular localization of disease rather than simply increasing overall OA incidence. 5

Psychosocial Factors

• Psychosocial workplace risk factors are associated with shoulder disorders, though the evidence is less robust than for physical exposures. 3

Important Clinical Caveats

The evidence quality for shoulder OA specifically is limited compared to knee and hip OA:

• Most studies examining occupational mechanical exposures and shoulder OA have high or moderate risk of bias, with only 2 of 7 studies in the most recent systematic review rated as low risk. 1
• The level of evidence ranges from low to very low for all specific occupational exposures and shoulder OA. 1
• Standardized classification systems for shoulder disorders based on patho-anatomical origins have proved poorly reproducible, hampering epidemiological research. 3

The broader systematic review of occupational OA (covering multiple joints) did not identify shoulder-specific strong evidence, focusing instead on knee and hip OA. 6 This reflects the relative paucity of high-quality research specifically examining shoulder OA and occupation compared to lower extremity joints.

Compressive, torsional, pulling, and angular movements common in certain occupations may result in soft tissue injuries that increase OA development. 5

Prevention Implications

• There is currently little evidence that primary prevention or workplace treatment strategies are highly effective for shoulder disorders. 3
• The main preventive task involves limiting exposure at the workplace, particularly reducing combinations of overhead work, heavy lifting, forceful activities, and awkward postures. 5
• More research is required around cost-effectiveness of different prevention strategies. 3