Part B: Computer-Related Injuries, Illnesses and Discomfort
The muscles, tendons, ligaments, joints, bones, cartilage and discs in the spine make up the musculoskeletal system. An injury or illness to these parts is called a musculoskeletal disorder (MSD). Some MSDs, such as carpal tunnel syndrome, can affect nerves as well.
To understand these injuries, it is necessary to understand the structure and function of various parts of the body.
Muscles are tissues made up of very small fibers. Muscles contract and relax to make movement.
Tendons connect muscles to bones. Tendons are also made up of fibers, but these fibers do not stretch or shrink. The tendons transfer the force from the muscle to move the bone. Some tendons, like those in the wrist and hand, are covered with a sheath that contains a lubricating fluid. These tendons pass back and forth through the sheath as the muscles tighten or relax.
Ligaments connect bones to form a joint. Joints are covered by ligaments that form a joint capsule, which holds the ends of the bones together and allows movement. The joint also contains lubricating fluid. Some ligaments, such as those in the shoulder, elbow and knee are shielded from friction by a bursa, a small sac filled with fluid.
Nerves carry messages throughout the body — sending and receiving information to and from the brain. Nerves allow us to see and hear, and also feel pain.
This chapter covers the most common injuries that computer operators experience because of poor ergonomics at work. The symptoms and major risk factors are described for each disorder. Generally, the more time a worker is exposed to these risk factors, the greater the chance of developing one of these injuries.
CARPAL TUNNEL SYNDROME
Carpal tunnel syndrome (also known as median neuritis) is a painful condition of the hands and wrists. It is caused by pressure on the median nerve, which runs from the shoulder, down the arm, to the hand. In advanced cases, carpal tunnel syndrome can make the simplest chore or activity impossible, such as holding a frying pan, folding laundry or lifting an infant.
Symptoms: In addition to pain, the symptoms of carpal tunnel syndrome include numbness and tingling in the hands. These symptoms are usually felt in the first three fingers and the base of the thumb. Often the pain and other symptoms are worse at night or during sleep.
Figure 4 shows the parts of the hand and wrist that are involved. Tendons of the fingers, blood vessels, and the median nerve all pass through what is called the carpal tunnel. The carpal tunnel is formed by the carpal ligament in the wrist. Swelling and steady irritation of the tendons that pass through the carpal tunnel create pressure on the median nerve.
Risk factors: The major causes of carpal tunnel syndrome are:
- working with bent wrists
- a high rate of repetition using the hands
- a lack of rest for the hands and wrists and
- forceful hand motions.
All of these risk factors are not necessary to get carpal tunnel syndrome. For example, computer operators get carpal tunnel syndrome even though modern computers only require a very light force to press the keys. The awkward posture, intense keying and lack of rest periods are more than enough to cause problems.
Carpal tunnel syndrome is a very serious injury. It can occur in one wrist, or both (bilateral carpal tunnel). Carpal tunnel syndrome affects workers in many industries such as meatpacking, grocery checkout and assembly work. AFSCME members, especially among those who work with computers, are also victims of carpal tunnel syndrome.
Early and proper treatment is important for this condition. Treatment should start out conservatively with rest and physical therapy. Surgery should not be the first choice. The person’s job may have to be redesigned to remove or reduce risk factors at work. Otherwise, the symptoms are likely to get worse and require surgery to relieve the pain.
Tendinitis is a very common ailment. Pain and inflammation in the arms or elsewhere result from overuse and awkward posture. Tendons can eventually fray and tear. Remember, tendons are like chords that connect muscles and bones. Tendons twist and bend, but do not stretch or shrink.
This is also known as “tennis elbow.” Pain begins in the elbow and then spreads to the forearm. The main conditions that cause this problem are repetition, rotating the forearm or force.
Unlike the tendons in the elbows, some are covered with a sheath. The tendons of the fingers, for example, are covered with a synovial sheath. The sheath is filled with a fluid that lubricates the tendon as it slides back and forth through the sheath. This fluid is called synovial fluid.
When workers perform highly repetitive motions, too much fluid is produced in the sheath. The extra fluid builds up and the sheath becomes swollen and causes pain. Awkward posture, such as doing intensive keyboard work with the wrists bent backward, is also an important risk factor.
Stenosing means constriction. The passageway through the sheath becomes smaller. This occurs when tendons become rough or irritated and the tendon sheaths are inflamed. The swollen sheaths then press on the tendons.
This is a specific example of a stenosing tenosynovitis. In DeQuervain’s disease, the tendons at the side of the wrist and the base of the thumb are affected, causing pain and inflammation. These tendons are connected to the muscles on the back of the forearm. When these muscles tighten, the thumb is pulled back away from the hand.
DeQuervain’s disease develops with too much friction of the tendons in the thumb and the sheath. The sheath gets thicker because of the friction, which in turn constricts the tendons. The risk factors for this disorder include tight gripping and a clothes-wringing motion.
Ganglionic cysts are also known as “Bible bumps.” This ailment involves a tendon sheath on the back side of the wrist. In this instance, the fluid inside the sheath builds up so much that it actually forms a bump under the skin (Figure 5). Once again, repetitious work with bent wrists is the main risk factor.
BACK, NECK AND SHOULDER PROBLEMS
Computer operators commonly feel pain in the lower back. This is often the result of sitting for long periods in a chair that does not provide support to the lower back (lumbar) region (Figure 6). If the chair is not helping to maintain the back in an upright position, the back muscles must do more work, causing fatigue. Inappropriate chairs also contribute to slouching and other postures that put pressure on the spine.
Tilting the head backward causes a pain in the neck and shoulders. This commonly happens when the monitor is too high. When seated at the computer, the top of the monitor should be at or below eye level.
Improper placement of work materials is also a common cause of neck problems. Repeatedly bending the head downward to look at a paper flat on a desk and then tilting the neck backwards to see the computer screen can cause pain and stiffness in the neck. A document holder at the same height, distance, and angle as the computer screen eliminates the need for this motion. Shoulder strain and soreness can also occur if the computer operator must reach too far to use the mouse. The mouse should be next to the keyboard, and appropriately placed for either right- or left-handed users.
EYE AND VISION PROBLEMS
Eye and vision problems are the most common health complaints of computer operators. This comes as no surprise to anyone who has worked for long periods of time in front of a computer. The usual symptoms include:
- eye fatigue or eye strain (asthenopia)
- blurred vision
- burning, itching or tearing eyes
- temporary change in ability to see colors and
Many operators have reported that they feel their vision has worsened after working with computers. Some started wearing corrective lenses and others have required frequent prescription changes since beginning work on the equipment. Most investigators have not found any connection between computer use and long-term damage to the eyes.
The most common risk factors for headaches, eye and vision problems are:
- unclear, flickering or characters that are too small
- reflections and glare on the screen
- light that is too bright
- being too close or too far from the screen
- too much time looking at the screen and
- stressful working conditions.
Computer operators should have yearly vision examinations. Make sure your eye care professional knows that you work with a computer. The fact that you work with a computer may affect the type of prescription lenses that you need.
Just about every working person knows the feeling of being under pressure to meet the demands of the job. In workplaces across the country, employers and workers are striving for greater efficiency. In offices, management has looked to computer technology as a way to get more work done in less time and with fewer people.
Stress is not only a feeling; it causes changes in body functions (physiology) such as the release of a variety of hormones, increased breathing, quickened pulse and the production of more stomach acid. Workers suffering from repeated, prolonged or continuous job stress may experience:
- frequent headaches
- loss of appetite
- short temper
- backache and stomach problems
- high blood pressure and/or
- heart disease.
Stress can also increase the risk of being injured on the job, weaken the body’s resistance to disease, lead to substance abuse, and contribute to marital and other social problems.
Conditions that cause stress (stressors) can be divided into two general categories, the work environment and the organization of work.
Environmental factors that lead to stress include:
- uncomfortable temperatures, humidity and poor air quality
- improper lighting
- noise and
- equipment and furniture that are not the right shape or size.
When the physical working conditions are uncomfortable or inappropriate, the computer operator must do something to adapt to the unsuitable conditions. The effort to cope with the environment is added to the already existing demands of the job, thereby increasing the level of stress.
The organization of work involves the manner in which work is done. Numerous organizational factors can make computer work more stressful, such as:
- repetitive tasks
- a lack of participation in decision-making and control over how to do your job
- lack of breaks or work not requiring a keyboard
- excessive overtime
- unreasonable pace of work and
- computer monitoring.
In addition to the actual design of computer work, other job conditions can contribute to the stress of operators. These include low wages, absence of career advancement opportunities and inadequate child care.