The term ‘contact stress’ has been used extensively in documents and discussions on computer use suggesting it presents an injury risk for computer users.
Contact stress is defined in the OSHA Computer workstations eTools document (2003) as:
Internal stress that occurs when a tendon, nerve, or blood vessel is stretched or bent around a bone or tendon. External contact stress occurs when part of your body rubs against a component of the workstation, such as the chair seat pan or edge of the desk. Nerves may be irritated or blood vessels constricted as a result
However, the significance of contact stress for computer users remains open to debate. To help understand the evidence on this issue Wellnomics conducted a comprehensive review of the published research literature on ergonomics and occupational health for the search terms ‘contact stress’ and ‘local mechanical stress’. In total this search identified 984 articles, but only six were identified as being relevant to office workers. These papers were reviewed in more detail to determine their findings (contact us if you would like to see the analysis of these papers in more detail).
The published research shows that contact stress is a fairly well identified risk factor in medium to heavy, repetitive, manual job tasks but there was little convincing evidence to suggest it is a significant risk factor for computer users.
It is plausible that discomfort could occur from contact on sharp edges such as the desk edge, but the current literature does not support this as being associated with the development of musculoskeletal symptoms, disorders or any medical health ailment.
Whilst it is obviously prudent to control any possible sources of contact on sharp edges with good workstation design (rounded desk edge) and good working postures (resting forearms, not wrists) the avoidance of contact stress is, in of itself, unlikely to have a strong impact on preventing or controlling incidence of computer related pain conditions and absenteeism. In practice contact stress doesn’t appear to be a significant health concern for office workers.
There may, of course, still be specific and unusual cases where contact stress could be an issue, such as in the situation of a worker who has poor circulation or poor sensation, or someone with para or quadraplegia, where discomfort from sharp contact may not be readily felt. However, for the rest of workers the obvious discomfort which will come from any sharp or uncomfortable contact will be more than enough to prompt them to adjust their position in relation to the surface and thereby prevent any long term ‘contact stress’ injury as described by the definition above.