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Hand and Arm Basics

There are many kinds of medical conditions that have ergonomic causes among office workers, including muscle disorders, tendon disorders, and nerve disorders. These are often collectively referred to as MSDs, or Musculo-skeletal Disorders which describes the affected tissue rather than the inferred cause of the disorder. See our MSD Descriptions further below on this page for more details about these conditions.

After reading through the list below you may want to learn and use our Recommended Keyboard Shortcuts (pdf). These will help reduce static positioning on the mouse and encourage relaxed hands while working- very popular with many computer users!

10 Things You Should Know about Hand & Arm Injuries
1. Because of the complexity and subtle differences between disorders, physicians don’t always diagnose MSDs correctly or easily. The most knowledgeable medical specialists for MSDs are generally considered to be Physiatrists, or physical medicine specialists.

2. MSDs can happen when there is very little repetitious work. Possible causes of MSDs include:

  • Repetition. Doing the same motion over and over in the same manner, particularly when there is little in the way of rests or break periods.
  • 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 MSDs are:

  • Break up repetitious work.
  • Relax. Don’t use your muscles to hold your fingers, 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- especially when ‘hitting’ the keys or squeezing the mouse.
  • 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 MSDs. 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- Examples of poor job design are infrequent or inflexible breaks, low activity variety, and fast pace.
  • Stress control – Examples of stressors are deadlines, monitoring, and bad management.
  • Individual workstyle – 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, excessive mousing (e.g. grasping the mouse while paused to read or mousing rather than using page Up/Down button) and where the individual places the mouse.

5. Most MSDs 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 MSDs 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. MSDs 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 MSD prevention rules without looking for consequences. Every fix has a possible 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 MSD 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). MSDs 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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Musculo-Skeletal Disorders (MSDs)

Descriptions of MSDs: Computer-related injuries can be broadly termed Musculo-Skeletal Disorders or MSD’s – which include a range of medical conditions affecting muscles, tendons, joints, or nerves. MSD’s have also been called RSI or Repetitive Strain Disorders, CTD or Cumulative Trauma Disorders, however many experts prefer the MSD term since it doesn’t imply or suggest the cause of the injury. Some examples of MSD’s include muscle sprain & strain, tendonitis and carpal tunnel syndrome.

Possible Causes: Most employees can use computers with little risk of discomfort or injury. However, improper work habits, poor ergonomics, or the presence of risk factors can increase the risk. Ergonomic and Personal Risk Factors are conditions or behaviors that can increase your chances of developing an MSD or other work related injury.
Examples of Ergonomic Risk Factors include:

  • Awkward postures such as typing with bent wrists
  • Static postures (not enough movement)
  • High repetition or
  • Too much force when keying or mousing

Examples of Personal Risk Factors include:

  • Medical conditions such as diabetes or Thyroid disorders
  • Poor physical capacity
  • Non-work activities such as computer gaming
  • Smoking
  • Stress

The symptoms of MSD’s may include pain, muscle fatigue, soreness, spasm, or numbness. If you have symptoms of MSD’s which don’t improve after making ergonomic changes please seek appropriate medical advice.

Muscle disorders
Muscle Spasm: A spasm is a sudden, involuntary contraction of a muscle or a group of muscles. It is sometimes accompanied by a sudden burst of pain, but is usually harmless and ceases after a few minutes.
Muscle Strain: A strain is an injury to a muscle in which the muscle fibers tear as a result of overstretching. Strains are also known as pulled muscles. The equivalent injury to a ligament is a sprain.
Myalgia: means “muscle pain” and is often caused by overuse, over-stretching of a muscle, or by stress. Cervical Myalgia, neck tension syndrome and cervical strain are common examples related to computer work. These can occur if the work involves chronic tension, awkward postures or repeated bending of the neck.
Myofascial Pain Syndrome is described as a painful, chronic muscle condition associated with Muscle Trigger Points that can make symptoms worse when aggravated.

Tendon Disorders
Tendonitis is an inflammation of the tendons or sheaths surrounding the tendons, and causes movement to be painful. Tendonitis can occur from keying or mousing with the wrists bent, or in the shoulders from frequent reaching.
Tenosynovitis: A painful swelling and thickening of the sheath surrounding some tendons.
Stenosing Tenosynovitis: Irritation and roughening of the tendon surface. This condition may lead to stiffness, snapping, and jerking motions when moving a finger for example.

  • De Quervain’s disease is an example of Stenosing Tenosynovitis that occurs at the base of the thumb and in the wrist.
  • Trigger Finger is an example of Stenosing Tenosynovitis that occurs in the fingers.

Epicondylitis is a tendon disorder that occurs at the elbow where the muscles controlling wrist and finger movements attach to the arm bones.

  • Lateral Epicondylitis (Tennis Elbow) occurs on the lateral or outer side of the elbow and is from bending the wrist to the outside, bending the wrist up/ back or from straightening the fingers out.
  • Medial Epicondylitis (Golfers Elbow) occurs on the medial or inner side of the elbow and is from gripping the fingers or bending the wrist down.

Ganglion Cyst is a disorder of the tendon sheath. It occurs when the sheath swells up with too much lubricating fluid causing a bump under the skin.
Rotator Cuff tendonitis occurs in the shoulder and often results from working with the arms held out away from the body or when repeatedly reaching up too high.

Ligament Disorders
Ligament Sprain: Ligaments are tough fibers that connect bone to bone. A sprain or tearing of the ligamentous fibers can occur if a ligament is over stretched.

Nerve disorders
Carpal Tunnel Syndrome is an irritation of the Median Nerve as it passes through the narrow Carpal Tunnel in the wrist. Symptoms include pain, numbness, and tingling of the first three fingers and the thumb. This nerve irritation can occur from swelling of the wrist tendons or from fluid retention and other conditions.
Cubital Tunnel Syndrome is a pinching or compression of the Ulnar Nerve at the elbow. This nerve is often referred to as the “funny bone”. This condition can occur from working with flexed or bent elbows.
Guyon canal stenosis is an Ulnar Nerve compression at the wrist. This can occur from working with the wrist bent to the sides when keying or mousing.
Thoracic Outlet Syndrome involves compression and irritation of nerves and blood vessels as they exit the thorax near the upper chest and shoulder area. The symptoms can be similar to carpal tunnel syndrome and the entire arm can feel like it is going to sleep.
Other disorders related to extensive computer use
Computer Vision Syndrome symptoms vary and may include; dry eyes, or red, itchy, watery eyes; fatigue & heaviness of the eyelids; and difficulty focusing the eyes. CVS does not cause eye damage, but can cause headaches, neck aches, and muscle spasms. Computers can be hard to read because the small dots that produce screen images are blurry around the edge, and are constantly being re-written. This forces the eye to continually refocus to keep images sharp. Excessively high monitor placement, wearing contact lenses, and monitor “flicker” can make symptoms worse.
Fatigue and stress may be secondary to an MSD or other medical condition. It may be caused by poor job design, work organization, over-working, lack of job control on the part of the user, under utilization of skills, high speed repetitive working, or social isolation, or other psycho-social issues at the job. Many symptoms described by DSE users reflect stress arising from their task. All of these factors have been linked with stress in DSE work, although clearly they are not unique to it.

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