The development of an index for the proximal upper extremity

Analysis techniques specific to the proximal upper extremity have historically been overlooked in the field of ergonomics. This research effort provides a methodology that will allow the ergonomics practitioner to analyze a job and predict whether or not that job exposes workers to increased risk of proximal upper extremity disorders. Literature from the fields of physiology, biomechanics, and epidemiology was assimilated in order to understand the theories of pathogenesis of disorders in the rotator cuff and to identify the risk factors associated with proximal upper extremity disorders. A retrospective epidemiological study was conducted to identify job task variables that may contribute to the occurrence of proximal upper extremity disorders. Two proximal upper extremity constructs were proposed: a fatigue-based model and a compressive load-based model. The constructs incorporated lessons learned from the literature and results from the epidemiological study. Validation of the models was performed using data from the epidemiological study. It was determined that the fatigue-based model was a good predictor of proximal upper extremity disorders.