How To Buy Home/Small-Office Desks
Adapt Low-Cost Desks To Protect Wrists And Neck From Pinched Nerves
Oct 31, 2008
Many people who buy furniture for small or home offices opt for lowest cost. They assume it is sufficient to place a computer screen and keyboard or a notebook or laptop computer on the writing surface of a desk. This arrangement places the screen at a height that can strain the neck and it places the keyboard where it can cause painful problems with the wrist, forearm and shoulders.
With notebook or laptop computers, the small screen can exacerbate the neck problems, and the touch pad or button pointing devices can further strain arms.
As with home and small-office seating, ergonomic principles can be applied to low-cost desks without breaking a budget.
Avoiding pinched nerves in the neck
The correct height for the screen places the top third of the display at the height of the eyes of the person using it while that person's head is upright. It is about an arm's length from the eyes.
In seminars on ergonomics, Dr. Mark Vettraino of Task Group International, a specialist who treats spinal conditions, shows an X-ray of a person's neck before and after three years of notebook computer use. The 'before' X-ray shows the spine of the neck (cervical) with a perfect healthy curve. In the 'after' X-ray the curve has gone because this person sat for too long looking down at a screen with the weight of the head supported by the neck on an angle.
When the spine loses its natural curve disks can bulge to abrade and pinch the nerves, causing pain that sets up a reaction of muscle spasms.
Avoiding degenerative disk disease
When a person holds his or her head in one position for too long, as in prolonged use of a notebook computer, the disks harden, leading to degenerative disk disease, in which bone painfully compresses nerves.
The neck in Dr. Vettraino's X-rays is his own, demonstrating how easy it is for even someone who knows about the spine to make the mistake.
Low-cost computer holders
The way to fix this is not expensive. Holders are available that can position CRT or flat-screen displays at the correct height.
There are also stands that hold a notebook computer at the correct height, as shown below. This puts the keyboard much too high, so it pays to invest in a plug-in or wireless auxiliary keyboard and pointing device.
Avoiding pinched nerves in wrist
The healthiest keyboard position for wrists, arms and shoulders is below the writing surface at a slight negative angle (back edge lower than the front). The angle between the forearm and upper arm should be slightly more than 90 degrees, the wrists should be straight and the upper arms should hang vertically close to the body, advises Professor Alan Hedge, director of Cornell University's Human Factors and Ergonomics Research Group.
If the computer user has to flex the wrists to operate the keyboard, this causes problems with the nerves in the carpal tunnel and strains muscles of the forearm. If the user has to reach so the upper arms are not vertical and close to the body, this can place stress on the shoulder muscles.
Low cost keyboard holders
Low cost keyboard trays on drawer slides can be mounted on the underside of the desk writing surface. Some home-office desks are now available containing drawer-type keyboard trays, as illustrated.
When a person is using a simple flat keyboard tray, any legs or feet on the rear of the keyboard should be in or down so the keyboard lies flat. It is possible to approximate the negative angle tilt by placing a pad under the front edge of the keyboard. Better is an economical drawer-type keyboard tray that can be set at a negative angle, as shown below.
Healthier mousing
It is important also to avoid reaching for a mouse placed on the writing surface. The best position for a mouse tray is at the same height as the keyboard and to right or left of the letter keys (i.e., over the number keys of a conventional keyboard). Some drawer-type keyboard trays are fitted with a mouse holder, as in the computer desks illustrated.
An alternative is a trackball that fits beside the keyboard on the tray and can be operated by the fingertips.
Several other accessories are available to aid healthy and productive computer use.
Fully ergonomic furniture can be outside a limited home-office or small-office budget. However, low-cost alternatives are available that help to reduce the neck and muscle pain and injury that result from improper placing of screen and keyboard.
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