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 Healthy Steps for Prevention of Carpal Tunnel Syndrome
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Carpal Tunnel Syndrome (CTS) is a repetitive motion disorder. Repetitive motion
and cumulative trauma disorders are disorders of the musculoskeletal and nervous
systems. These disorders may be caused or aggravated by repetitive motions, forceful
exertions, vibration, mechanical compression (using tools with hard and sharp
edges on their handles), sustained or awkward postures, or exposure to noise over
extended periods of time.
These disorders can affect nearly all tissues – the nerves, tendons,
tendon sheaths, and muscles – with the upper extremities being the most
frequently affected. These painful and sometimes crippling injuries develop
gradually over periods of weeks, months, and years, and result from repeated
actions such as twisting and bending the hands, arms, and wrists. A common risk
factor for developing these disorders is the use of force combined with repetitive
motion over time.
The most common occupational diseases associated with repetitive motion are
tendon disorders such as tendonitis, tenosynovitis, De Quervain's disease, trigger
finger, Raynaud's syndrome, and carpal tunnel syndrome.
Tendon disorders are very common and often occur at or near the joints where
the tendons rub against ligaments and bones. The most frequently noted symptoms
of tendon disorders are 1) a dull aching sensation over the tendon, 2) discomfort
with specific movements, and 3) tenderness to touch. Recovery is usually slow,
and the condition may easily become chronic if the cause is not eliminated.
Carpal tunnel syndrome (CTS) is the compression and entrapment of the median
nerve where it passes through the wrist into the hand – in the carpal
tunnel. The median nerve is the main nerve that extends down the arm to the
hand and provides the sense of touch in the thumb, index finger, middle finger,
and half of the fourth (or ring) finger. When irritated, tendons housed inside
the narrow carpal tunnel swell and press against the nearby median nerve. The
pressure causes tingling, numbness, or severe pain in the wrist and hand; this
pain is often felt at night. Also, the internal pressure results in a lack of
strength in the hand and an inability to make a fist, hold objects, or perform
other manual tasks. If the pressure continues, it can damage the nerve, causing
permanent loss of sensation and even partial paralysis.
CTS develops in the hands and wrists from repetitive and/or forceful manual
tasks performed over a period of time. For example, the meatpacking industry
is considered one of the most hazardous industries in the United States because
workers can make as many as 10,000 repetitive motions per day in assembly line
processes (such as deboning meats) with no variation in motion Consequently,
stress and strain are placed on the wrists and hands, which can result in CTS.
CTS affects workers in many fields. It is common among draftsmen, meatcutters,
secretaries, musicians, assembly-line workers, computer users, automotive repair
workers, and many others. CTS can be treated with steroids, anti-inflammatories,
physical therapy, or with surgery to loosen the transverse carpal ligament.
Recovery of wrist and hand function is often, but not always, complete.
CAUSES
Like many skeletomuscular disorders, CTS has a variety of causes. It is often
the result of a combination of factors, such as
- Genetic predisposition. Certain people are more likely than others
to get CTS. The amount of natural lubrication of the flexor tendons varies from
person to person. The less lubrication, the more likely a person is to develop
CTS. One study has related the cross-sectional shape of the wrist and the associated
geometry of the carpal tunnel to CTS. Certain tunnel geometries are more susceptible
to tendon irritation.
- Health and lifestyle. People with diabetes, gout, and rheumatoid arthritis
are more prone than others to develop CTS, as are those experiencing the hormonal
changes related to pregnancy, menopause, and the use of birth control pills.
Job stress has also been linked to an increased likelihood of CTS. CTS seems
to be more frequent among alcoholics.
- Repetitive motion. The most common cause of CTS that's been attributed
to the workplace is repetitive motion. When you flex your hand or fingers, the
flexor tendons rub against the walls of the carpal tunnel. If you allow your
hand time to recover, this rubbing is not likely to lead to irritation. The
amount of recovery time you need varies from fractions of a second to minutes,
depending on many factors: 1) the genetic and health factors mentioned above,
2) the intensity of the flexing, 3) the weight of any objects in your hand,
and 4) the extent to which you bend your wrist during flexing.
- Trauma. A blow to the wrist or forearm can make the tendons swell;
this may cause or encourage the onset of CTS.
PREVENTION
Computer keyboard users can take several steps to lower their chances of developing
CTS. Some of these center around the configuration of the workplace, or "ergonomics."
Others have to do with human factors.
- Ergonomics. Proper seating is crucial to good ergonomics. The height
of your seat and the position of your backrest should be adjustable. The chair
should be on wheels so you can move it easily. Arm rests on the chair, though
optional, are often helpful.
- Table height. To adjust the chair properly, look first at the height
of the table or desk surface on which your keyboard rests. On average, a height
of 27-29 inches above the floor is recommended. Taller people will prefer slightly
higher tables than do shorter people. If you can adjust your table, set your
waist angle (see bulleted list below) at 90 degrees, then adjust your table
so that your elbow makes a 90 degree angle when your hands are on the keyboard.
- Wrist angle. If your keyboard is positioned properly, your wrists should
be able to rest comfortably on the table in front of the keyboard. Some keyboards
are so "thick" that they require you to bend your hands uncomfortably
upward to reach the keys. If so, it will help to place a raised wrist rest on
the table in front of the keyboard. A keyboard that requires you to bend your
wrists is a common cause of CTS among computer users.
- Elbow angle. With your hands resting comfortably at the keyboard and
your upper arms vertical, measure the angle between your forearm and your upper
arm (the elbow angle). If it is less than 90 degrees, raise the seat of your
chair. If the angle is greater than 90 degrees, lower the seat. Try to hold
your elbows close to your sides to help minimize "ulnar displacement"
– the sideways bending of the wrist (as when reaching for the "Z"
key).
- Waist angle. With your elbow angle at 90 degrees, measure the angle
between your upper legs and your spine (the waist angle). This too should be
about 90 degrees. If it is less than 90 degrees, your chair may be too low (and
your knees too high). You may need to alter the position of the backrest or
adjust your own posture (nothing provides better support than sitting up straight).
(Note: If making your waist angle 90 degrees changes your elbow angle, you may
need to readjust the height of your chair or table.)
- Feet. With your elbows and waist at 90 degree angles, your feet should
rest comfortably flat on the floor. If they don't, adjust your chair and table
height and repeat the steps above. If your table isn't adjustable and your feet
don't comfortably reach the floor, a raised footrest can help. Otherwise, you
may need a different table.
WORK ROUTINE
You need very little recovery time between keystrokes to cool and lubricate
the flexor tendons. If you type constantly, however, the need for recovery builds.
Further, working with your hands bent upward at the wrists or frequently bending
your wrists sideways heightens the friction within the carpal tunnel. It takes
longer to recover from these motions. Working under stress (deadline pressure,
anger, or other anxiety) can make matters even worse.
Many studies recommend a 10-15 minute break each hour to give yourself the
recovery time you need. This needn't be a break from productive activities,
just a break from your keyboard.
Exercises can help, too. Try the following:
a) Make tight fists, hold for one second, then stretch your fingers out wide
and hold for five seconds. Repeat several times.
b) With arms outstretched in front of you, raise and lower your hands several
times. Rotate your hands ten times (make circles in the air with the fingertips).
Variety is the key. CTS occurs most frequently in workers whose motions are
not only repetitious but are kept up for hours at a time. If you use a keyboard,
structure your workdays to include a mix of activities each hour. For example,
instead of typing all morning and filing all afternoon, mix typing and filing
throughout the day.
EARLY DETECTION
The most painful cases of CTS are those that have gone undetected or untreated
over a long time. CTS can be caught easily in its early stages, however, and
much of the pain and all of the disability can be avoided.
Early symptoms include a tingling in the fingers, often beginning several hours
after work activity has stopped. Because of this delay in the appearance of
symptoms, many CTS sufferers don't make the connection between their work activities
and the pain they feel until it's too late. Over time, the tingling can lead
to stiffness and numbness in the fingers and hand and then to severe wrist and
hand pain.
For many individuals, the early symptoms of CTS go unnoticed. Employers and
co-workers can help one another identify the onset of CTS by watching for and
pointing out any unconscious shaking of the hands, rubbing of the wrists, or
unusual postures or hand positions at the keyboard.
At the first sign of CTS, you should be examined by a doctor who specializes
in hand and wrist disorders. The doctor can perform a number of simple tests
to detect CTS and can prescribe specific steps for avoiding the problem.
The following 10 questions can help you decide on what will be a good ergonomic
design for your situation:
- How will the computer be used?
- Who will be using the computer? If the computer will only be used by
one person then the arrangement can be optimized for that person's size and
shape; features such as an adjustable-height chair may be unnecessary. If the
computer will be used by several people, you need to create an arrangement that
most closely satisfies the needs of the extremes (that is, the smallest and
tallest, thinnest and broadest persons) as well as those in between these extremes.
- How long will people be using the computer? If it's only a few minutes
a day, then ergonomic issues may not be a high priority. If it's more than 1
hour per day, it is advisable that you create an ergonomic arrangement. If it's
more than 4 hours, then you should immediately implement an ergonomic arrangement.
- What kind of computer will be used?
- Desktops. Most ergonomic guidelines for computer workstation arrangements
assume that you will be using a desktop system where the computer screen is
separate from the keyboard.
- Laptop computers are growing in popularity and are great for short
periods of computer work. Guidelines for laptop use are more difficult because
laptop design inherently is problematic – when the screen is at a comfortable
height and distance the keyboard isn't and vice versa. For sustained use, you
should consider purchasing:
- an external monitor and an external keyboard (preferably a keyboard with
a negative-tilt tray)
or
- a docking station; then arrange your workspace to create a good workstation
layout.
- What furniture will you use? Make sure that the computer (monitor, CPU system
unit, keyboard, mouse) are placed on a stable working surface (nothing that
wobbles) with adequate room for proper arrangement. If this work surface is
going to be used for writing on paper as well as computer, you need a flat surface
that is between 28-30 inches above the floor (suitable for most adults). You
should consider attaching a keyboard/mouse tray system to your work surface.
Choose a system that is height adjustable, that allows you to tilt the keyboard
down away from you slightly for better wrist posture, and that allows you to
use the mouse with your upper arms relaxed and as close to the body as possible
and with your wrist in a comfortable and neutral position.
- What chair will be used? Choose a comfortable chair for the user to sit
in. If only one person is using it, the chair can even be at a fixed height,
providing that it is comfortable to sit on and has a good backrest that provides
lumbar support. If more than one person will be using the computer, consider
buying a chair with several ergonomic features. Studies show that the best seated
posture is a reclined posture of 100-110 degrees – NOT the upright 90
degree posture that is often portrayed. In the recommended posture, the chair
starts to work for the body, and there are significant decreases in postural
muscle activity and in intervertebral disc pressure in the lumbar spine. Erect
sitting is NOT relaxed, sustainable sitting – reclined sitting is.
- What kind of work will the computer be used for? Try to anticipate what
type of software will be used most often.
- Word processing - arranging the best keyboard/mouse position is high
priority.
- Surfing the net, graphic design - arranging the best mouse position
is high priority.
- Data entry - arranging the best numeric keypad/keyboard is a high priority.
- Games - arranging the best keyboard/mouse/game pad is a high priority.
- What can you see? Both your documents and the computer monitor should be
positioned for easy viewing.
In positioning documents:
- Make sure that any paper documents that you are reading are placed
as close to the computer monitor as possible and that these are at a similar
angle - use a document holder where possible.
- Use a document holder that can be comfortably seen. There are three
different ways to arrange a document holder:
- Use an in-line document holder that a) sits between the keyboard/keyboard
tray and screen and b) is aligned with your body midline. All you have to do
is look down to see the documents and raise your eyes to see the screen.
- Use a screen-mounted document holder; position this on the same side of
your screen as your dominant eye
- Use a freestanding document holder. Position this next to the side of the
screen and slightly angle it so that it follows a curve from the side of the
screen.
In positioning your monitor:
- Make sure the monitor is in front of you and facing you, not angled
to the left or right. This helps to eliminate excessive neck twisting. Also,
use the screen scroll bars to ensure that whatever is being viewed most is in
the center of the monitor, rather than at the top or bottom of the screen.
- Center the monitor so that your body and/or neck isn't twisted when
looking at the screen. However, if you are working with a large monitor and
spend most of your time working with software like MS Word (which defaults to
creating left-aligned new pages) and you don't want to have to drag these to
more central locations, try aligning yourself to a point about 1/3 of the distance
across the monitor from the left side.
- Put the monitor at a comfortable height that doesn't make you tilt
your head up to see it or bend your down to see it. When you are seated comfortably,
your eyes should be in line with a point on the screen about 2-3" below
the top of the monitor casing (not the screen). Sit back in your chair at an
angle of around 100-110 degrees (i.e. slight recline) and hold your right arm
out horizontally. Your middle finger should almost touch the center of the screen.
From that starting position you can then make minor changes to screen height
and angle to suit. Research shows the center of the monitor should be about
17-18 degrees below horizontal for optimal viewing, and this is where it will
be if you follow the simple arm extension/finger pointing tip. You actually
see more visual field below the horizon than above this (look down a corridor
and you'll see more of the floor than the ceiling), so at this position you
should comfortably be able to see more of the screen. If the monitor is too
low, you will crane your neck forward; if it's too high, you'll tilt your head
backwards and end up with neck/shoulder pain.
- Bifocals and progressive lens - Even if you wear bifocals or progressive
lenses, if you sit back in your chair in a reclined posture (with your back
at around 110 degrees), and if you slightly tilt the monitor backwards and place
it at a comfortable height, you should be able to see the screen without tilting
your head back or craning your neck forward. Postural problems with bifocals
can occur if you sit erect or even hunched forward. The problem with low monitors
is that they cause neck flexion and suffer more from glare. Recent studies have
shown that the best position for a computer monitor is for the center of the
screen to be at around 17.5 degrees below eye level. Try to align your eyes
with the top of the viewing area of the screen; this should put the center about
right geometrically.
- Viewing distance - The monitor should be at a comfortable horizontal
distance for viewing, which usually is around an arm’s length. Sit back
in your chair and raise your arm and your fingers should touch the screen. At
this distance, you should be able to see the viewing area of the monitor without
making head movements. If text looks too small, then either use a larger font
or magnify the screen image in the software rather than sitting closer to the
monitor.
- Screen quality - Use a good quality computer screen. Make sure that
the text characters on your screen look sharp, and that they are a comfortable
size. (You can change the screen resolution to find a comfortable and clear
character size). If you can see the screen flickering out of the corner of your
eye, you should try increasing the refresh rate of your monitor. (On a PC, you
can change monitor resolution and refresh rates using the monitor control panel
in your settings folder. On a Mac, you can use the monitor control panel). You
may also consider using a good quality glass anti-glare filter or an LCD display
(like a laptop screen).
- Eye checkup - There are natural changes in vision that occur in most
people during their early 40s. It's a good idea to periodically have your eyes
checked by a qualified professional.
- Screen adjustments - If any screen adjustments feel uncomfortable,
change them until the arrangement feels more comfortable or seek further professional
help.
- Posture - Good posture is the basis of good workstation ergonomics and is
the best way to avoid a computer-related injury. To ensure good posture:
- Make sure that you can reach the keyboard keys with your wrists as flat as
possible (not bent up or down) and straight (not bent left or right).
- Make sure that your elbow angle (the angle between the inner surface of the
upper arm and the forearm) is at 90 degrees or greater to avoid nerve compression
at the elbow.
- Make sure that your upper arm and elbow are as close to the body and as relaxed
as possible for mouse use – avoid overreaching. Also make sure that your
wrist is as straight as possible when the mouse is being used.
- Make sure your chair has good back support. Also check that your feet can
be placed flat on the floor or on a footrest.
- Make sure your head and neck are as straight as possible.
- Make sure your posture feels relaxed.
- Keep it close
- Make sure that those things you use most frequently are placed closest
to you so that they can be conveniently and comfortably reached.
- Make sure that you are centered on the alphanumeric keyboard. Most
modern keyboards are asymmetrical in design (the alphanumeric keyboard is to
the left and a numeric keypad to the right). If the outer edges of the keyboard
are used as landmarks for centering the keyboard and monitor, your hands will
be deviated because the alphanumeric keys will be to the left of your midline.
Move the keyboard so that the center of the alphanumeric keys (the B key) is
centered on your mid-line.
- Make sure that the phone is also close to you if you frequently use
it.
- A good workstation ergonomic arrangement will allow any computer user to
work in a neutral, relaxed, ideal typing posture that will minimize the risk
of developing injury. Ideally, your keyboard should be placed on a height-adjustable
negative-tilt tray. The mouse should be on a flat surface that's 1-2 inches
above the keyboard and moveable over the numeric keypad. If you want a surface
at the level of the keyboard’s base, then make sure that this surface
can also be angled downwards slightly to help to keep your hands and wrists
in a neutral position while you are using your mouse. Also, keep your elbows
as close to the body as possible while you work.
- Where will the computer be used? Think about the following environmental
conditions where the computer will be used:
- Lighting - Make sure that the lighting isn't too bright. You shouldn't
see any bright light glare on the computer screen. If you do, move the screen,
lower the light level, or use a good quality, glass anti-glare screen. Also,
make sure that the computer monitor screen isn't backed to a bright window or
facing a bright window so that the screen looks washed out (use a shade or drapes
to control window brightness).
- Ventilation - Make sure that you use your computer somewhere that has
adequate fresh-air ventilation and that has adequate heating or cooling so that
you feel comfortable when you're working.
- Noise - Noise can cause stress; stress tenses your muscles, which can
increase injury risks. Try to choose a quiet place for your workstation, and
use low volume music (preferably light classical) to mask the hum of any fans
or other sound sources.
- Take a break! All ergonomists agree that it's a good idea to take frequent,
brief rest breaks.
Practice the following:
- Eye breaks - Looking at a computer screen for more than 15 minutes changes
how the eyes work, causes you to blink less often, and exposes more of the eye
surface to the air. Every 15 minutes, you should briefly look away from the
screen for a minute or two to a more distant scene, preferably something more
than 20 feet away. This lets the muscles inside the eye relax. Also, blink your
eyes rapidly for a few seconds. This refreshes the tear film and clears dust
from the eye surface.
- Micro-breaks - most typing is done in bursts rather than continuously. Between
these bursts of activity you should rest your hands in a relaxed, flat, straight
posture. During a micro-break (less than 2 minutes) you can briefly stretch,
stand up, move around, or do a different work task (e.g., make a phone call).
A micro-break isn't necessarily a break from work, but it's a break from the
use of a particular set of muscles that's doing most of the work (e.g., the
finger flexors if you're doing a lot of typing).
- Rest breaks - every 30 to 60 minutes you should take a brief rest break.
During this break, stand up, move around, and do something else. Go and get
a drink of water or coffee. This allows you to rest and exercise different muscles,
and you'll feel less tired.
- Exercise breaks - there are many stretching and gentle exercises that you
can do to help relieve muscle fatigue. You should do these exercises every 1-2
hours.
- What about ergonomic gizmos? - These days just about everything is labeled
as being "ergonomically designed." Some of these so-called ergonomic
products can actually make things worse.
If you're thinking about buying an "ergonomic product" ask yourself
the following 4 questions:
1. Does the product design and the manufacturer's claims make sense?
2. What research evidence can the manufacturer provide to support its claims?
(Be suspicious of products that haven't been studied by researchers.)
3. Does it feel comfortable to use the product for a long period? Some ergonomic
products may feel strange or slightly uncomfortable at first because they often
produce a change in your posture that's beneficial in the long-term. Think of
these products as being like new shoes that initially may feel strange but then
feel comfortable after being used for a while. If a product continues to feel
uncomfortable after a reasonable trail period (say at least a week) time then
stop using it.
4. What do ergonomics experts say about the product? (If they don't recommend
it, don't use it.)
There are many computer-related "ergonomic" products, the most
common ones being:
"Ergonomic" keyboards - Most of these are keyboards where the alphanumeric
keys are split at an angle. For a non-touch typist, this design can be a disaster!
The split design only addresses issues of hand ulnar deviation, and research
studies show that vertical hand posture (wrist extension) is more important.
There is no consistent research evidence that most of the split-keyboard designs
currently available really produce any substantial postural benefits. For most
people, a regular keyboard design works just fine if it's put in the proper
neutral position.
"Ergonomic" mice - Many of these mice designs or alternative input
device designs can work well to improve your hand/wrist posture. However, it's
important to check that you can use these with your upper arm relaxed and as
close to your body as possible. Remember that overreaching to an "ergonomic
mouse" defeats any benefits of this design.
Wrist rests - These were very popular a few years ago, but research studies
haven't demonstrated any substantial benefits for wrist rests. In fact, a wrist
rest can actually increase pressure inside the carpal tunnel by compressing
the undersurface of the wrist. (Take a look at your wrist and you'll probably
see blood vessels that shouldn't be compressed!) If you choose to use a wrist
rest, using one with a broad, flat, firm surface design works best. Rest the
heel of your palm on the surface, NOT your wrist. Try not to rest while you're
actually typing, but rest in between bursts of typing movements. Avoid soft
and squishy wrist rests because these will contour to your wrist, restrict the
freedom of movement of your hands, and encourage more lateral deviation during
typing. The surface of a typical wrist rest that's been used often erodes away,
which means that the user has been sliding his or her wrists over the surface,
compressing the blood vessels often visible at the wrist. Remember, your hands
should be able to glide above the surface of a wrist rest during typing. Don't
lock them in place on the rest while you type.
Support braces/gloves - There is no consistent research evidence that wearing
wrist supports during computer use actually helps reduce the risk of injury.
If you do like wearing a wrist support, make sure that it keeps your hand flat
and straight, not bent upwards. There is some evidence that wearing wrist supports
at night in bed can help relieve symptoms for those with carpal tunnel syndrome.
Height adjustable, split work surfaces - With respect to wrist posture, the
issues are the same for height-adjustable, split work surfaces and sit-stand
work surfaces:
• If the surface is too low, the hand will be in greater extension.
• If the surface is too high, the elbow will be in sustained flexion.
• If it's a flat surface, then it's just the same argument as is used
above for a negative-slope keyboard tray arrangement.
You can't set a flat work surface at an appropriate height for all five main
tasks of office work – keyboarding, using a mouse, writing, viewing documents
and viewing the screen. These each require different heights for an optimal
arrangement. A negative-slope keyboard tray system serves as the height and
angle adjustment mechanism for the keyboard. Also, the mouse platform serves
as the height and angle adjustment for the mouse when attached to a work surface
that is set for writing height. Monitor height is best adjusted by a separate
monitor pedestal rather than by trying to move a whole work surface.
Five Tips for Using a Laptop Computer
- Un-ergonomic laptops - The design of laptops violates a basic ergonomic
requirement for a computer: namely that the keyboard and screen should be separated.
In the early days of personal computing, desktop devices integrated the screen
and keyboard into a single unit, and this resulted in widespread complaints
of musculoskeletal discomfort. By the late 1970s a number of ergonomics design
guidelines were written and all called for the separation of screen and keyboard.
The reason is simple: with a fixed design, if the keyboard is in an optimal
position for the user, the screen isn't; if the screen is optimal, the keyboard
isn't. Consequently, laptops are excluded from current ergonomic design requirements
because none of the designs satisfy this basic need. This means that you need
to pay special attention to how you use your laptop because it can cause you
problems.
- Laptop user type - how do you use your laptop? Are you an occasional user
who works on your laptop for short periods of time, or are you a full-time user
with the laptop as your main computer? Occasional users will have less risk
of problems than full-time users. All users should pay some attention to how
they use their laptop, but full-time users may have more problems.
- Laptop posture - As indicated above, laptops violate basic ergonomic design
requirements, so using a laptop is a tradeoff between poor neck/head posture
and poor hand/wrist posture.
- Occasional users - Because the neck/head position is determined by the
actions of large muscles, you are better off sacrificing neck posture rather
than wrist posture. For occasional use:
- - Find a chair that is comfortable and that you can sit back in
- - Position your laptop in your lap for the most neutral wrist posture that
you can achieve
- - Angle the laptop screen so that you can see this with the least amount of
neck deviation
- Full-time users - if you use your laptop at work as your main computer
you should:
- - Position it on your desk/work surface in front of you so that you can see
the screen without bending your neck. This may require that you elevate the
laptop off the desk surface using a stable support surface, such as a computer
monitor pedestal.
- - Use a separate keyboard and mouse. You should be able to connect a keyboard
and mouse directly to the back of the laptop or to a docking station.
- - Use the keyboard on a negative-tilt keyboard tray to ensure a neutral wrist
posture.
- - Use the mouse on an adjustable position mouse platform.
- - Follow the posture guidelines for working at a computer workstation.
- Laptop dimensions - Many laptops offer large screens (15" plus) and
can work as desktop replacements (giving the viewing area of a 17" monitor).
However, think about where you will most use your laptop to help you choose
the best size. The larger the screen, the more difficult it will be to use this
in mobile locations (e.g. airplane, car, train). There are a number of smaller
notebook and ultra portable laptops on the market. Consider issues of screen
size and screen resolution. A small screen (such as 12.1 inches) will be useful
in mobile settings, but if the resolution is high (like XGA – 1024 x 768)
make sure that you can read the screen characters and can easily use the input
device to point to areas on the screen. The smaller the laptop, the smaller
the keyboard, so make sure that you can comfortably type on a keyboard that
may be only 75% the size of a regular keyboard.
- Laptop weight - If you are a mobile professional who will be frequently
transporting your laptop, think about the weight of the system. The word “system”
here means the weight of the laptop plus the required accessories (power supply,
spare battery, external disk drive, zip drive, CD RW, etc.). Many lightweight
portables can become as heavy as regular laptops when you add the weight of
all of the components together. If your laptop plus components weighs 10 lbs.
or more, then you should certainly consider using a carry-on bag that has rollers
on it.
Tendonitis
Tendonitis is a form of tendon inflammation that occurs when a muscle or tendon
is repeatedly tensed from overuse of unaccustomed usage of the wrist and shoulder.
With further exertion, some of the fibers that make up the tendon can actually
fray or tear apart. The tendon becomes thickened, bumpy, and irregular in certain
areas of the body (like the shoulder), and the injured area may calcify. Without
rest and sufficient time for the tissues to heal, the tendon may be permanently
weakened. Tendonitis is common among power press operators, welders, painters,
and assembly line workers (like automobile, appliance, electronic production).
Tenosynovitis
Tenosynovitis is an inflammation or injury to the synovial sheath surrounding
the tendon. These sheaths secrete synovial fluid, which acts as a lubricant
to reduce friction during movement. Repetitive motion using the hands and wrists
may provoke an excessive secretion of synovial fluid, with the sheath becoming
swollen and painful. Repetitions exceeding 1,500 to 2,000 per hour produce symptoms
associated with tendon sheath irritation in the hands. Tenosynovitis affects
workers in jobs such as core making, poultry processing, and meatpacking.
Trigger Finger
Trigger finger, another tendon disorder, is attributed to the creation of a
groove in the flexing tendon of the finger. If the tendon becomes locked in
the sheath, attempts to move the finger will cause snapping and jerking movements.
The palm side of the fingers is the usual site for trigger finger. This disorder
is often associated with using tools that have handles with hard or sharp edges.
Meatpackers, poultry workers, electronic assemblers, and carpenters are at risk
of developing trigger finger.
Raynaud's Syndrome
Raynaud's syndrome, or white finger, occurs when the blood vessels of the hand
are damaged as a result of repeated exposure to vibration for long periods of
time. The skin and muscles are unable to get the necessary oxygen from the blood
and eventually die. Common symptoms include intermittent numbness and tingling
in the fingers; skin that turns pale, ashen, and cold; and eventual loss of
sensation and control in the fingers and hands. This condition is also intensified
when the hands are exposed to extremely cold temperatures. This illness is associated
with the use of vibrating tools over time like pneumatic hammers, electric chain
saws, and gasoline powered tools. After long-term exposure – perhaps 10
to 15 years working 6 to 7 hours a day with vibrating tools – the blood
vessels in the fingers may become permanently damaged. There is no medical remedy
for white finger. If the fingers are fairly healthy, the condition may improve
if exposure to vibration stops or is reduced.
Other types of vibration may affect the entire body, producing overall fatigue
and potential permanent damage. Vibration in conjunction with prolonged sitting
may also result in degenerative changes in the spine. For example, drivers of
tractors, trucks, buses, construction machines, and other heavy equipment may
suffer from low back pain, and permanent abdominal, spinal, and bone damage.
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