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Keyboard discomfort

Arm and neck pain
Keyboard design
Keyboard results
Comment


Bandolier spends a fair amount of time with its faithful computer. Wonderful things computers, especially if you have a super whizzo Macintosh and a big screen. But interacting with it is not quite yet the science fiction vision of a polite conversation with a courteous slave with a brain the size of a planet. We interact through a keyboard, using eyes and hands.


The eyes can sometimes get a bit tired, especially looking from paper to screen and back again. That can be helped by a suitable pair of bi-focals. But it's the typing that can be the problem, and the hands, wrists, forearms and neck all protest from time to time. We can minimise that by getting our positions right, and sitting up straight, and a few exercises. But the keyboard, that is not something we often think about.


For some of us the aches can get worse, and develop into real problems, like tendonitis. Is there any evidence out there about the size of the problem (given how many of us use keyboards at work and at home), and whether keyboard design can help if we get into trouble? There's not much, but what there is might be of help.


Arm and neck pain


Most studies have concentrated on people who use keyboards a lot. An example [1] looked at workers in administrative jobs in Finland who used keyboards (VDUs) for more than four hours a week. It followed 232 who reported little or no neck pain at baseline for a year.


Using the criterion of local or radiating neck pain for at least eight days over the next year, it found that 52 of 180 respondents (34%) fulfilled this criterion. Female sex was about the only major predictor, together with a poor work environment.


A UK survey [2] of 21,000 randomly selected men and women of working age (16-64) asked questions about use of keyboards for more than four hours per working day, as well as questions on the one week and one year prevalence of pain in neck and upper arms. Responses from 58% had 4,889 responders in non-manual occupations, of whom 1,798 used keyboards for more than four hours a day and 2,901 did not.


One in three non-manual workers reported upper extremity or neck pain during the previous week. Increased wrist and hand pain was associated with frequent keyboard use, as well as neck pain in women and shoulder pain in men (Table 1).


Table 1: Reports of pain in arms, shoulders and neck in men and women in non-manual occupations in the UK. Statistically significant differences between keyboard users and non-users are shaded



Pain in previous week, with adjusted prevalence ratio
Women
Men
Users
Non-users
Prevalence ratio
(95% CI)
Users
Non-users
Prevalence ratio
(95% CI)
Neck pain
22.9
18.3
1.3 (1.1 to 1.5)
14.8
13.8
1.1 (0.9 to 1.4)
Shoulder pain
21.2
17.5
1.2 (1.0 to 1.5)
16.4
12.3
1.4 (1.1 to 1.7)
Elbow pain
4.6
4.9
1.0 (0.7 to 1.5)
6.0
5.8
1.2 (0.8 to 1.7)
Wrist or hand pain
15.1
11.0
1.4 (1.1 to 1.7)
10.6
7.9
1.4 (1.0 to 1.8)
Tingling or numbness in upper arm lasting more than 3 minutes
18.1
16.4
1.1 (0.9 to 1.3)
13.3
12.9
1.1 (0.8 to 1.3)

Keyboard design


The effects of four different keyboard layouts was tested in a randomised, observer blinded study of workers with established tendonitis or carpel tunnel syndrome at the Lawrence Livermore National Laboratories in California [3]. The subjects were all employees, and were eligible to participate if they were full time employees using a computer keyboard for more than four hours a day or 20 hours a month, and whose injuries were recorded in the employer's illness database. All had the diagnosis for less than two years and none had previous hand or wrist surgery or experience of variable geometry keyboards.


Keyboards under test were the workers standard QWERTY keyboard (placebo), and three variable geometry keyboards: an Apple Adjustable keyboard (kb1), a Comfort Keyboard System (kb2), and a Microsoft Natural keyboard (kb3). At the time of randomisation, those randomised to their own keyboard had the keyboard taken away and cleaned, and returned with markings and an assurance that it had been altered.


Various tests on hands, wrists and arms were conducted at baseline and up to 24 weeks of keyboard use, by observers who were blind to the type of keyboard used. The workers themselves made other records about pain and functionality at intervals throughout the study.


Keyboard results


Eighty workers were randomised, twenty to each keyboard. Their average age was about 42 years, and about 60% were women. Worker characteristics were well balanced at baseline. No worker gave up using the placebo keyboard, one each gave up on keyboards 1 and 3, but nine stopped working with keyboard 2, five because of mechanical failure. Keyboard 2 was the most complicated.


For all three variable keyboards, more subjects had significant reductions in pain by 50% or more by six months than with the placebo keyboard (Table 2). Keyboard 3 had more responses, and the mean pain scores for this group was significantly lower at 18 and 24 weeks (Figure 1).


Table 2: Responses over six months to placebo and three variable geometry keyboards in workers with established tendonitis or carpal tunnel syndrome


Change in pain severity
Placebo
Keyboard 1
Keyboard 2
Keyboard 3
Worse
5
3
3
2
Same
10
8
6
7
At least 25% improvement
2
2
3
0
At least 50% improvement
3
7
8
11

Figure 1: Pain scores over six months





While pain scores increased with placebo after six weeks, they tended to fall with other keyboards, but particularly keyboard 3. Keyboard 3 was also the only keyboard where by six months there were significant improvements in functional status scores, particularly for writing, driving, tying shoe laces, performing jobs, using a keyboard and house work. Those workers who thought the variable geometry keyboard was better than their standard keyboard all had a significant reduction in pain.


Comment


Most of us would accept that spending hours over a hot keyboard can be tiring, and leave us aching. The tendonitis and pain in hands, wrists and forearms that some of us get can be quite severe. It is essential to make sure that position and placing are just right to avoid problems. Bandolier finds physiotherapists quite helpful, and some companies have specialists to check out positioning.


There is likely to be a residual burden of people who still have problems, though quite how much is uncertain. The UK study was interesting because it was a population-based examination. It indicated that 15% of British workers use keyboards more than four hours in a working day (and that was in 1998).


While upper extremity pain is common, there is more in people using keyboards a lot. Some of those will have significant pain because of tendonitis or carpal tunnel syndrome. For instance the baseline pain in the randomised trial would be sufficient for entry into acute pain studies. The evidence we have is that persistence with a variable geometry keyboard will make life a lot easier for about half of them.


References:

  1. T Korhonen et al. Work related and individual predictors for incident neck pain among office employees working with video display units. Occupational and Environmental Medicine 2003 60: 475-482.
  2. KT Palmer et al. Use of keyboards and symptoms in the neck and arm: evidence from a national survey. Occupational Medicine 2001 51: 392-395.
  3. P Tittiranonda et al. Effects of four computer keyboards in computer users with upper extremity musculoskeletal disorders. American Journal of Industrial Medicine 1999 35: 647-661.

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