Reports in the scientific literature and lay press have suggested that computer users are at increased risk of upper extremity musculoskeletal disorders (MSDs). Early studies often found elevated rates of MSD outcomes among keyboard users when compared to non-users. Attention soon focused on specific aspects of keyboard work that might be responsible for the observed rate increase. In this review, the epidemiological evidence examining associations between MSD outcomes and computer user posture and keyboard use intensity (hours of computer use per day or per week) are examined.

Results of epidemiological studies of posture and MSD outcomes have not been entirely consistent. Reasons for the inconsistency in results include cross-sectional study design (with possible failure to assure that measured exposure preceded health effect), imprecision of posture measures used, and difficulties involved in analyzing multiple related variables. Despite the inconsistencies, it appears from the literature that posture is an independent risk factor of modest magnitude for MSDs among computer users. It appears that lowering the height of the keyboard to or below the height of the elbow and resting the arms on the desk surface or chair armrests is associated with reduced risk of neck and shoulder MSDs.

Results of epidemiological studies examining computer use (hours keying per day or per week) are more consistent than those examining posture, although some inconsistency is observed. Reasons for the inconsistency include possible selective survival bias resulting from cross-sectional study design, differences in exposure categorization, and possible interaction with other exposure variables. Overall, the literature shows that daily or weekly hours of computer use is more consistently associated with hand and arm MSDs than with neck and shoulder MSDs.

Aim: The aim of this study was to determine whether upper extremity musculoskeletal disorders are more prevalent in intense computer users and the relation between cumulative hours of computer use and symptoms. Materials and Methods: The study group included 100 bank workers, who worked more than 6 h per day for at least 2 years on a video display unit and were recruited through convenience sampling. Sixty-five age and sex matched healthy subjects who worked not more than 2 h on computer keyboards for office work constituted the control group. Results: There were no significant differences between groups when the age and sex of the participants were considered. The results suggest a high prevalence of musculoskeletal disorders of the upper extremities among intensive computer users. The differences were statistically significant except in neck range of motion and left cubital tunnel syndrome. As the time spent on video display unit increased, there is a tendency in occurrence of symptoms, but only in carpal tunnel syndrome the relation is significant. Conclusions: The findings showed that cumulative computer use time increased the risk of musculoskeletal disorders in the upper extremities. As the duration of job increased, the risk for carpal tunnel syndrome significantly increased. Further studies with the inclusion of a larger number of cases and potential risk factors would help clarify the role of variables in the aetiology of work-related neck and upper limb disorders.