Workplace use of an adjustable keyboard: adjustment preferences and effect on wrist posture.

This study presents an evaluation of an adjustable keyboard based on subjective preference and wrist joint motion during typing. Thirty-five computer users used the adjustable split design keyboard for 7-14 days during their usual work and were instructed to adjust the keyboard to the opening angle they preferred. At the end of this period, three-dimensional motion analysis was performed to compare the distribution of wrist joint angles while subjects typed on a conventional keyboard and the adjustable keyboard adjusted to the subject's preferred angle. The mean preferred opening angle was 14 degrees +/- 10. The mean ulnar deviation of the subjects who selected the opening angles between 21 and 28 degrees (n = 12) decreased from 18 degrees +/- 5 on the flat to 14 degrees +/- 5 on the adjustable (p < 0.05), while those who selected 0 to 10 degrees (n = 6) and 11 to 20 degrees (n = 17) split angles showed no significant differences in ulnar deviation. Mean wrist extension on the adjustable keyboard was 17 degrees +/- 5 and was significantly less than the 24 degrees +/- 5 observed on the conventional keyboard and most likely due to the presence of palm support. On average, subjects reported that the adjustable keyboard was more comfortable (0.5 +/- 0.5) (worse = -1, same = 0, better, = 1) in comparison with the conventional keyboard.

Effect of four computer keyboards in computer users with upper extremity musculoskeletal disorders.

Eighty computer users with musculoskeletal disorders participated in a 6-month, randomized, placebo-controlled trial evaluating the effects of four computer keyboards on clinical findings, pain severity, functional hand status, and comfort. The alternative geometry keyboards tested were: the Apple Adjustable Keyboard [kb1], Comfort Keyboard System [kb2], Microsoft Natural Keyboard [kb3], and placebo. Compared to placebo, kb3 and to a lesser extent kb1 groups demonstrated an improving trend in pain severity and hand function following 6 months of keyboard use. However, there was no corresponding consistent improvement in clinical findings in the alternative geometry keyboard groups compared to the placebo group. Overall, there was a significant correlation between improvement of pain severity and greater satisfaction with the keyboards. These results provide evidence that keyboard users may experience a reduction in hand pain after several months of use of some alternative geometry keyboards.

Risk factors for musculoskeletal disorders among computer users.

This investigation of current epidemiologic and ergonomic research demonstrates consistent relationships between certain computer-related factors and musculoskeletal disorders.

Effect of keyboard keyswitch design on hand pain.

This randomized clinical trial evaluated the effects of keyboard keyswitch design on computer users with hand paresthesias. Twenty computer users were matched and randomly assigned to keyboard A (n = 10) or B (n = 10). The keyboards were of conventional layout and differed in keyswitch design. Various outcome measures were assessed during the 12 weeks of use. Subjects assigned keyboard A experienced a decrease in hand pain between weeks 6 and 12 when compared with keyboard B subjects (P = 0.05) and demonstrated an improvement in the Phalen test time (right hand, P = 0.006; left hand, P = 0.06). Keyboard assignment had no significant effect on change in hand function or median nerve latency. We conclude that use of keyboard A for 12 weeks led to a reduction in hand pain and an improved physical examination finding when compared with keyboard B. There was no corresponding improvement in hand function or median nerve latency.