Health Society of South Africa

PROTECTING YOUR HANDS AND WRISTS FROM CTDs
Industrial ergonomics

What's the Harm?

Your hands grip and release and your wrists twist and bend millions of times a year. Precise finger movements allow you to assemble small parts, sort materials and press buttons and keys. But over time, repeated wear and tear may damage tissues. Your fingers may tingle or you may feel pain or numbness in your hand, arm or shoulder. Such symptoms are often linked to a group of illnesses called cumulative trauma disorders or CTDs.

Risks to Remember
CTDs may take months or years to develop, so it's easy to miss early signs of trouble. But by recognising a few of the big CTD risk factors - harmful positions, excessive force and frequent repetition - you can take steps to prevent injury and control any present symptoms.

Harmful Positions
Bending your hand backward or toward the palm. Pinching your fingers against the thumb. Any such extreme position puts pressure on muscles, tendons and nerves. Even "good positions" can be harmful if they're held for too long.

Excessive Force
Force is pressure or strain on the body. You create force when you grip a tool or rotate your wrist. Contact force occurs when you press a hard surface, such as a tool handle or a lever, against your palm. Combine force with a harmful position and your risk increases.

Frequent Repetition
If you make the same move the same way for long periods of time, your muscles get tense and tired. Without rest, they can't recover for normal function. So if you repeat the same movements for another long stretch, your already-tired muscles are at greater risk of injury.

Set Yourself Up Right

Proper positioning reduces pressure on muscles and tendons. You're safest and your motions are strongest when your hands and wrists are near neutral position. A few simple adjustments can often make a big difference. Try the tips below. They may help keep you closer to neutral.

Use Your Whole Hand
Use as much of your hand as possible when grasping. This limits pressure caused by pinching.
Hold an object near its center of gravity, so the weight is balanced.

Work Within Reach
You should be able to reach your work without bending your wrist.
Stand above the object or sit so your hand, wrist and forearm can move straight out from your body. Keep your elbows in close to your waist.
Adjusting the work surface to slant toward you may bring your work into easier reach.

Gloves Might Help
Wearing gloves can reduce vibration and protect hands from cold.
Choose gloves that fit properly and are flexible, so gripping isn't made more difficult.
Tape or finger cots can increase friction, so you can reduce force. They also help protect your fingertips from cuts and pressure.

Neutral Position
When your wrist is in a straight (neutral) position, the muscles and tendons in your hand can move freely. In addition, blood circulates easily, feeding tissues and helping to repair any minor damage.

Use the Best Tools
Handles or levers should extend the full length of your hand to avoid pressing into your palm.
Choose in-line or pistol-grip tools, depending on the position of the work surface.
Single-handled tools, levers and bars should have a grip diameter that fits comfortably in your hand, usually between 30 and 50 mm. The grip span for pliers or cutters should range between 65 and 90 mm, depending on your hand. Comfortable grip sizes reduce force during use.
Textured or cushioned handles provide an easier grip.
Push-to-start power tools have less kickback than trigger-start tools.
Keep tools sharp and in good repair. They'll require less force to use.

Avoid These Positions
If possible, avoid putting any extra pressure on your hands and wrists. Bending or twisting them too far in any direction is risky.

Avoid twisting your wrist too far to either side.
Avoid bending your wrist too far up or down.
Avoid pinching your fingers together.
Avoid pressing into your palm or using your hand as a hammer.

More You Can Do

Become aware of your hands. Notice how you use or abuse them. Then improve your habits both at home and at work. Do your best to alternate tasks and stay fit.

Alternate Tasks
Give your hands and wrists a rest. If possible, vary tasks to use different muscles throughout the day. And when you get home, give yourself time to recover. Make sure your hands and wrists are relaxed and pain-free before you pull weeds, sand boards, knit or play piano or guitar. In fact, try to avoid any task that requires forceful or precise movements. Use the hours right after work to read, take a walk or visit with family and friends instead.

Stay Fit
When you're fit, a healthy blood supply feeds your body. This helps tired or damaged tissues recover faster. Stay fit by getting at least 30 minutes of physical activity throughout each day. Eating less fat and more fruits and vegetables help, too. Get fit by losing any extra kilograms. If you smoke, you know you should quit. Why not do it now? Your blood circulation is likely to improve, helping soft tissues to stay healthier and heal faster.

Communicate

If your hands or wrists are at risk or if you're already having pain, pay attention. Think through your tasks. Which risks can be controlled? Maybe a co-worker has a suggestion. Don't feel foolish about asking for help. Talk with your supervisor about finding new ways to do your job. Prevention is the only way to really protect your hands and wrists from cumulative trauma.

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