A prospective study for upper-extremity cumulative trauma disorders of workers in aircraft manufacturing

Occupational diseases affect 15 to 20% of all Americans. Cumulative trauma disorders (CTDs) account for 56% of all occupational injuries. The recognition and control of occupational injuries has become a major concern of employees, employers, medicine, and the federal government because of health risk and related costs. Upper-extremity CTDs are identified by the National Institute for Occupational Safety and Health as one of the ten most significant occupational health problems in the United States. It is estimated by the year 2000 that 50 cents on the dollar will be spent on CTDs. Although enlightened aircraft employers have developed primary prevention strategies, primary prevention can never be expected to eliminate 100% of the cases. To evaluate several preventive activities, a CTD risk-assessment program was developed and implemented in cooperation with a major aircraft manufacturer employing over 8000 workers. This program was focused on objectively identifying the relationship of work and other activities to an individual worker experiencing CTDs. Early identification has been linked, when applicable, to intervention algorithms for medical care, job task modification, workplace accommodation, and training. A prospective study group of 212 workers who used rivet guns was placed into a four-way experimental design for ergonomic posture training, exercise training, and rivet-gun type (primary factors). A statistical model was developed for the level of CTD risk and evaluated using the SAS software program (SAS Institute, Inc, Carry, NC). Statistical analysis of the primary factors without regard to associated variables (covariates) demonstrated that only posture training had a beneficial risk reduction for the individual. The impact (beneficial or detrimental) for exercise training and for vibration-dampening rivet guns was probably obscured because of the large variability of the responses regarding the associated variables (covariates). When the covariates were analyzed in conjunction with the four experimental groups, a positive benefit from ergonomic posture training and exercise training was demonstrated for the following groups: the dominant han, time spend in an awkward position, number of standard rivets bucked, number of parts routed, number of parts ground, number of vibration-dampening rivets bucked, and newly hired individuals. A negative effect (increase in individual risk level) for current employees using a vibration-dampening rivet gun was demonstrated. This prospective study helps to identify the possible benefit of education and training for controlling CTDs and demonstrates the usefulness of being able to evaluate materials, methods, machines, and environments as they relate to the individual's risk level for the development of upper-extremity CTDs.