Integrating ‘psychosocial’ factors into a theoretical model for work-related musculoskeletal disorders

The psychosocial aspects of jobs, in addition to their biomechanical aspects, have demonstrated significant relationships with work-related musculoskeletal symptoms and disorders (WRMSDs). Current models that seek to explain these associations build on the stress paradigm and propose that job strain impacts WRMSDs through increases in muscle tension; alterations in endocrine, immune, neurological and vascular systems that condition tissue injury and repair; and higher cognitive processes that alter symptom awareness and evaluation. These models vary in the emphasis placed on worker characteristics as opposed to work stressors. The paper provides a critical review of these models and draws on concepts advanced in the field of occupational safety to propose a modification of these approaches. The model advanced here integrates psychosocial and biomechanical risk factors as characteristics of work environment and emphasizes the role of management systems and the work environment as key sources of strain. Strain, as indicated by the physiological, behavioural and other responses of the worker, in turn influences WRMSDs and related outcomes as well as worker performance and productivity. The integrated model also takes into account the importance of viewing the work environment as a dynamic phenomenon with interaction among risk factors and between workers and managers.