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Monday, October 8, 2001
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A professional hazard...
Raman Mohan

IF you use computers at work and notice a tingling feeling in your fingers, hours after you are back home from work, you could be the next victim of Carpal Tunnel Syndrome — the malady of the information age. Computer users the world over, especially in India, are becoming more and more prone to this wrist-related painful condition. The culprits in their case are the keyboard and the mouse. The incorrect use of these peripherals for long hours causes what is known as the Carpal Tunnel Syndrome (CTS) in the medical world. It is a painful hand disorder caused by stressful and repetitive motions of the hand.

Although the site of the injury is the wrist, pain is usually felt in the hand. Excessive movement of the wrists or holding the wrists in static positions for long periods of time can irritate the nerves, tendons, and arteries inside a narrow formation of ligament and bone at the wrist known as the carpal tunnel.

Besides computer users, this painful condition affects workers in many fields. It is a common problem among draftsmen, secretaries, musicians, assembly-line workers, automotive repair workers, and many others. With the increasing use of computers in offices and homes worldwide, wrongly positioned wrists have become the prime cause of the CTS. The condition can be treated with steroids, anti- inflammatory drugs, physical therapy or surgery to loosen the transverse carpal ligament.

Recovery of wrist and hand function is often, but not always, complete. Prevention, therefore, is the best way out. CTS can be detected early easily, however, and much of the pain and all of the disability avoided.

 

What causes CTS

Carpal Tunnel Syndrome is most often the result of a combination of factors. Genetic predisposition is one of these.


Figure A: Gently press the hand against a firm, flat surface, stretching the fingers and the wrist. Hold for five seconds.

Figure B: Clench your fist tightly, then release.

Figure C: Fan out your fingers when you unclench your fist.

Many of us are more prone to it than others. The natural lubrication of the flexor tendons varies from person to person. The less the lubrication, the more you are prone to CTS. Computer users’ health and lifestyle has a close bearing on CTS. People suffering from diabetes, gout, and rheumatoid arthritis are more likely to suffer from this condition than others. Doctors also say that women can be especially susceptible to this malady due to hormonal changes related to pregnancy, menopause, and the use of birth control pills. Among men, alcoholics are prime targets for CTS.

At the work place, the most common cause of CTS is repetitive and stressful motion. When you use your hand and fingers to work on the computer, the flexor tendons rub against the walls of the carpal tunnel. This is unlikely to cause irritation if the hand gets a recovery time. The amount of recovery time varies according to circumstances, the genetic and health factors, the flexing intensity and the extent of wrist bending. Generally, you need almost no recovery time between keystrokes.

However, if you type constantly, the recovery time requirement builds up. The friction within the carpal tunnel increases greatly when you use a keyboard or a mouse as the hands are bent upward at the wrists. It takes longer to recover from these motions. Work stress including deadline pressure, anger and anxiety can make matters even worse.

The first signs of CTS include a tingling feeling in the fingers. This happens hours after work has stopped. This delay in manifestation of symptoms makes us think that the problem is unrelated to computer related work. We realise the truth too late.

Over a period, tingling is followed by stiffness and numbness in the fingers and hand, and then to severe wrist and hand pain. Colleagues can help one another identify the onset of CTS by looking out for any unconscious shaking of hands, rubbing of the wrists, or other similar but unusual postures or hand positions at the keyboard. As soon as you notice any of these you should consult a doctor who can give you tests to determine if you suffer from CTS.

Preventing CTS

Ergonomics (configuration of your work place or station) has everything to do with CTS. While bad ergonomics is the prime cause of CTS, good ergonomics the best prevention tool. Proper seating comes first in ergonomics. The height of your seat and the position of its backrest should be adjustable. Armrests on the chair are also helpful.

Your wrists should rest comfortably on the table. Many keyboards are thicker and these require you to bend your hands upward to access the keys. In that case, a suitably raised wrist rest will help. A keyboard that makes you bend your wrists is the biggest cause of the CTS, especially in India where ergonomics is relatively unknown outside the IT industry offices.

A thumb rule is that if the angle between your forearm and the upper arm in vertical position is less than 90 degrees, you need to adjust the height of your chair. In case the angle is greater than that, you need to lower the seat.

Exercises

The American Physical Therapy Association has devised a set of exercises to prevent CTS among computer users. These exercises are not stressful and should not normally cause any pain. However, if you notice pain or discomfort, you might already be suffering from CTS. In that case you need a doctor, not these exercises which are basically designed to be preventive.

Before beginning a typing job and during breaks throughout the day, take time to do the following stretching exercises:

Gently press the hand against a firm, flat surface, stretching the fingers and the wrist, as shown in Figure A. Hold for five seconds.

To strengthen the muscles along the wrist, clench your fist tightly as shown in Figure B, then release, fanning out your fingers as shown in Figure C.

...that can now be tackled

Typists can now reduce their risk of carpal tunnel syndrome and other repetitive motion injuries with the new Vertical-Split Keyboard. Any touch typist can use it without re-training. Available online at www.safetype.com, the keyboard was developed by Ergonomic-Interface Keyboard Systems, Inc. and tested by research scientists at Cornell University’s Human Factors and Ergonomics Laboratory.

"With the vertical keyboard, you’re virtually never in a high-risk position," says Dr. Alan Hedge, who led the Cornell study.

The keyboard is essentially two halves of the conventional flat keyboard, which are placed upright on a base. The typist’s hands are kept in the most neutral position possible, with palms facing each other and thumbs up. With keys facing outward, the wrists are placed in a neutral, untwisted position. This posture greatly reduces the strain that contributes to Repetitive Stress Injury as well as ordinary discomfort.

"Keyboard makers have typically been reluctant to make substantial changes in the design of keyboards," explains Dan Spencer of Ergonomic-Interface Keyboard Systems, Inc. "Our new Vertical Split-Keyboard signals a dramatic change in thinking about ways to significantly reduce the risk of Repetitive Motion Injury."

Spencer points out that the keyboard is not offered as a cure for any condition. Nevertheless, typists who are already experiencing some discomfort usually find that the completely neutral posture eases their pain.

Developed by Scottsdale, AZ-based Ergonomic-Interface Keyboard Systems, Inc., the Vertical-Split Keyboard is now being manufactured and is expected to be available in November 2001. — TNS

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