Carpal Tunnel Syndrome May Be The `In` Injury, But It Bears Attention.

October 04, 1989|By Betsy Lehman, Boston Globe.

People have been twisting wires, playing pianos, knitting sweaters, cutting meat, typing and scraping paint for a long time. They`ve had sore wrists at least as long.

But it`s only in the last five to 10 years that repetitive motion injuries, especially of the wrist, have become news, with big money riding on workers` compensation claims and medical treatments.

The best known among repetitive motion problems is carpal tunnel syndrome, which causes pain, tingling, numbness and, in severe cases, even permanent weakness of the fingers and thumb. The problem is actually in the wrist, in a narrow bony channel called the carpal tunnel, through which nine tendons and the median nerve must squeeze en route from the arm to the hand. If the tendons become inflamed and swollen, or if excess fluid crowds the confined space, the nerve, supplying feeling to the first three fingers and part of the thumb, can be compressed.

Stopping whatever activity caused the inflammation, splinting the wrist, taking anti-inflammatory drugs or having shots of steroids into the carpal tunnel can ease the compression. Sometimes, surgery is needed to relieve the pressure.

Under more stress

No one knows if there`s a lot more carpal tunnel syndrome, tendinitis and other ``overuse`` injury around, or whether we`re just much more aware of it. Some specialists theorize that faster assembly lines and computers that permit workers to type continuously for long periods are putting more and more stress on the body.

Others say that-fortunately-people are less tolerant of painful working conditions than they used to be. Still others say that individual

susceptibility, psychological stress or job dissatisfaction share the blame for overuse injuries.

It is clear that individual factors do influence who gets wrist pain;

women are more likely to report carpal tunnel syndrome than men, and it`s especially frequent in women who use birth control pills or are pregnant, probably because increased fluid volume crowds the carpal tunnel.

People with arthritis, diabetes, certain neck or back disorders, underactive thyroid gland production and other conditions may have wrist pain that may be unrelated to the tasks they perform.

Whatever the current ``epidemic`` actually represents, the new spotlight on repetitive motion has prompted research illuminating a host of factors you or your employer might consider to help you avoid getting hurt.

The biggest factors in overuse injuries are high-force and high-repetition tasks, says Stover H. Snook of the Liberty Mutual Research Center in Hopkinton, Mass., who teaches at the Harvard School of Public Health.

Researchers at the University of Michigan have found that either high-force or high-repetition tasks increase the risk of injury, but the combination of the two carries 30 times the risk of injury as other tasks.

A third major factor is body position. Unusual postures-long periods of hunching over, reaching overhead or bending the wrist-contribute to injury, says Dr. Lewis D. Pepper, assistant director of the Occupational and Environmental Health Center at Cambridge Hospital and a consultant to the state.

Relax already

The best positions are relaxed, natural ones. For hands, that means straight ahead, as if shaking hands, not angled sharply in any direction, particularly if you`re doing work that involves force, repetition or grasping or pinching with your fingers. Frequent grasping and pinching alone can provoke injury.

Vibration, cold and poor tool design also contribute to injury, Snook says.

Tool, desk and chair design matter if they`re used day after day for many hours, or if you already have pain. If you use tools or your desk only occasionally, their design is less important.

Snook, Pepper and other specialists offered these suggestions:

- If you use a computer, keep the keyboard low, even if you have to put it on your lap. Your wrist is most likely to be relaxed if your arm is angled down slightly.

The display screen should be higher than the keyboard, with the top of the screen at eye level. Looking down slightly (as when you study the middle of the screen) is the most natural position, Snook says.

- Whatever your task, whether you`re working at a computer, a workbench or an assembly line, use a chair of proper height. Footrests may help shorter people.

- Take frequent breaks. Listen to your body`s signals and rest if you`re getting sore or tired.

- When you`re new at a task, start slowly. Don`t expect peak performance immediately; give yourself time to adapt and build strength.

- Avoid bending your wrist, especially if you`re doing work that requires force or repetition. ``Bend the tool, not the wrist,`` specialists say. Bent- handled pliers, scissors and knives, for example, let you hold your wrist in a neutral position.