Work-related musculoskeletal disorders (MSD) commonly described as cumulative trauma disorders (CTD) are a major cause of worker impairment and disability.  In the American workplace "sprains and strains" are typically the largest category of claims in workers' compensation, representing over half of claims and dollar costs.  In 1996, the U.S. Bureau of Labor and Statistics released its most current data for 1996 in its annual survey of lost-worktime for all injuries and illnesses.  It reported a total of nearly 1.9 million injuries and illnesses in private industry workplaces required recuperation away from work beyond the day of the incident.  In 1997, the cost of workplace health and safety was estimated at over $418 billion in direct costs, and (using the lower range of estimates) indirect costs were $837 billion.  Although the pathogenesis of these disorders is not fully understood the need for reduction and prevention by employees, employers, insurance systems, health care systems, and government is clear.
Given the multifactorial etiology for MSD and its association with individual and workplace risk factors, their reduction and prevention will require a multidisciplinary effort.  The science of ergonomics, biomechanics, epidemiology, and medicine are being used to better understand the interdependence of MSD.  Ergonomics (Greek ergon = work and Greek nomos = law) is the study of the problems of people in adjusting to their environment; especially the science that seeks to adapt work or working conditions to suit the worker (the study of work).  Biomechanics (Greek bios = indicates life or living organism and mechanic = of or pertaining to machines or tools or acting like a machine) is the study of how the living organism performs activities (the study of how work is performed).  Biomechanics uses laws of physics and engineering to describe motion of various body segments and the forces that act upon these body parts during normal daily activities.  By this definition, biomechanics is a multidisciplinary science.  Epidemiology (Latin epidemia = of people and ology = the study of) is the medical science that focuses on the distribution and determinants of disease frequency in human populations and the application of the study to the control of the disease.  Medicine (Latin medicus = doctor or mederi = to heal) the science of diagnosing, treating, or preventing disease and other damage to the body or mind.
The implementation of a successful ergonomics program can benefit the employer and employee by:  (1) reducing the number and severity of work-related injuries and illnesses, (2) reducing employee turnover, (3) increasing productivity, (4) increasing product quality, and (5) increasing employee morale.  The study of biomechanics and ergonomics is further defined by terms such as human factors, anthropometry measurements, individual risk factors (age, gender, inherited genetic characteristic), workplace risk factors (methods, materials, machines, environment, and physical stressors), psychological factors, economic concerns, and return to work issues.

Biomechanics and Ergonomics of the Upper Extremity.  In Mayer TG, Gatchel RJ, Polatin PB, (eds). Occupational Musculoskeletal Disorders Function, Outcomes, and Evidence. Philadelphia, PA, Lippincott, Williams & Wilkins 111-141, 1999.  Melhorn JM, Hales TR, Kennedy EM.  Reference ID: 3172