Hand and Arm Basics


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Eyestrain Basics

Hand and Arm Basics

Ergonomic products:  pros/cons

Being Effective

Conventional vs. current wisdom

Ergonomic Chairs

Alternative Keyboards

A Checklist

Good ergo weblinks

Good Periodicals

Solving VDT Reflections (Mark Rea)

Hand and arm basics

There are many kinds of CTD (Cumulative Trauma Disorder) medical conditions that have ergonomic causes among office workers, including carpal tunnel syndrome and various kinds of tendon inflammation.

Some other disorders, such as myofascial pain syndrome, fibromyalgia, thoracic outlet syndrome, and reflexive sympathetic dystrophy are believed to be the results of cumulative trauma in some cases.

1. Because of the complexity and subtle differences between disorders, physicians don't always diagnose CTD's correctly or easily. The most knowledgeable medical specialists for CTD's are generally considered to be physiatrists, or physical medicine specialists.

2. CTDs can happen when there is very little repetitious work. Besides repetition, other possible causes include:

  • Holding one position. Muscles that hold a body part in position for long periods are more prone to fatigue than muscles that move a body part around.
  • Non-neutral postures. In this context, "posture" is the position of an individual joint, not overall body posture. Any posture significantly different from "neutral" is considered to be at risk for musculoskeletal distress. "Neutral" is considered to be the position about halfway through the available range of motion for the joint.
  • Localized pressure. Direct pressure on nerves or tendons can cause damage in the long run. The wrist is one location of concern. The elbow (the funny-bone or crazy-bone nerve) is another.
  • Use of force. Even small exertions can cause stress if small muscles are involved. Sudden, fast motions involving a jerk or snap.
  • Cold temperatures.
  • Vibration, as with hand-held power tools or whole-body vibration as caused by driving heavy equipment.

3. Keeping these causes in mind, some of the rules of thumb for preventing CTD's are:

  • Break up repetitious work.
  • Relax. Don't use your muscles to hold your hands or shoulders in a particular position. Keep your limbs and shoulders limp as much as possible, even during short pauses.
  • Use moderate postures for individual joints. Stay away from positions near the extremes of your joints' range of motion --- the most neutral joint position is about halfway.
  • Minimize contact with hard or sharp surfaces. This is especially important at the wrists and elbows.
  • Don't use too much force. Notice any exertions you have to make and see if they can be eliminated. "Exertions" don't have to involve breaking into a sweat. They can be subtle, such as pulling a hard-to-reach drawer or lifting a heavy file.
  • Move with an even motion. Avoid snapping the wrist or jerking against outside forces.
  • Keep your hands and fingers warm. Consider gloves or even fingerless gloves.
  • Break up exposures to vibration.

4. "Fitting the physical workspace to the worker" is often touted as the best way to prevent CTD. This is an incomplete view. Although physical workstation design, physical tool design, and adjustability are important, there are many other work-related factors. Three less tangible but extremely important factors are job design, stress control, and individual workstyle.

Examples of job design are infrequent or inflexible breaks, low activity variety, and fast pace. Examples of stressors are deadlines, monitoring, and bad management. Examples of harmful workstyles (in the context of computer work, for instance) are how hard the individuals hits keys, how the individual holds his/her wrists, and where the individual places the mouse.

5. Most CTD's are preventable and curable if caught early. The key is to notice trouble when it starts --- and do something about it. Early signs may include persistent pain, tingling, numbness, burning, or aching. The signs may be constant or may occur mostly after certain activities. The drastic cures --- such as surgery --- are not reliable and should be a last resort. Nevertheless, a health professional should be consulted when you are concerned about possible early signs.

6. Some people get CTD's because their bodies are vulnerable to them. For example, carpal tunnel syndrome seems to be related to diabetes, overweight, thyroid conditions, hormone conditions such as those caused by hysterectomy or removal of both ovaries, rheumatoid arthritis, previous injuries, and other conditions. Smoking may also increase the risk. Anyone with any of these conditions --- particularly obesity --- should be especially careful about prevention.

7. CTD's can happen because of non-work activities. Hobbies, sports, driving, and even sleeping positions can contribute to them. Any attempts at treatment or prevention should include a look at off-the-job factors.

8. One of the most important preventive measures is 'variety.' In other words, change posture and activities often. If possible, take breaks before getting tired. Extremely short breaks can be very helpful of frequent enough. A "break" doesn't have to be a rest break --- it can simply involve doing something else for awhile.

9. Don't follow CTD prevention rules without looking for consequences. Every fix has a drawback. Every ergonomic rule or gizmo has a downside which can possibly make matters worse rather than better. The best way to evaluate ergonomic fixes is by considering all the ergonomic risk factors described above in #2. Example: a wrist rest may force a straighter wrist (vertically) but may put too much pressure on the underside of the wrist or make the individual bend the wrist sideways to reach side keys.

10. Total CTD prevention involves ergonomics (changing the environment), ergonomics education (changing work styles or habits), medical management (optimizing treatments and return-to-work procedures), and management (monitoring statistics to find the most hazardous jobs and working proactively). CTD's usually cannot be adequately dealt with without all four approaches happening together. Many obstacles to good ergonomics are not scientific, medical, or engineering reasons ... they are political in nature.

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