We have a substantial and consistent body of knowledge that demonstrates the strong association of MSDs with many exposures found in workplaces and have high attributable fractions for many of these. Exposure measures have improved over the years from initially just considering job titles, to self-reports of physical and psychosocial risk factors, to structured observations, and more recently to technical measures of muscle activity or modeled joint loads. Identified risk factors now include physical or mechanical factors (force, posture, repetition, duration), work organizational factors (worker perceptions of demand, control, and co-worker and supervisor support; the so-called psychosocial factors) as well as individual factors. These relationships have been demonstrated in multiple types of work, with a wide variety of exposure assessment approaches, and a wide variety of study designs, including high-quality prospective cohort studies; the NIOSH MSD Consortium Studies are an example of a concerted attack on this question.

While it is possible to identify risk factors without having knowledge of the underlying patho-physiology using epidemiological approaches, acquiring a strong relationship between the statistical and physiological information would give us more confidence that the relationships are causal, and will increase the likelihood that intervening on the risk factors will have an effect on MSD development and burden.

How good are our MSD risk factors? We ask this question because it is possible to have an excellent intervention that is based on risk factors derived from a preceding etiologic study, yet the effects on MSDs were disappointing. It may be the risk factors themselves were misleading, or that the identified risk factors were too far removed from the target tissue pathophysiology, or that the intervention itself was the weak link. 

For more information, read the editorial Why have we not solved the MSD problem?, by Dr. Richard Wells.