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Pathology => Human Diseases => Repetitive Stress Injury (RSI)
Repetitive Stress Injury (RSI)
INTRODUCTION
Repetitive Stress Injury (RSI), work-related physical symptoms caused by excessive and repetitive use of the upper extremities. Repetitive stress injuries occur especially when tasks are performed under difficult conditions, using awkward postures and poorly designed equipment. Common tasks that cause RSI include typing for hours on a computer keyboard, cutting meat, or working on a production line. Other terms used to describe RSI include cumulative trauma disorder,repetitive motion disorder, and occupational overuse syndrome. Recently, the term upper extremity musculoskeletal disorder has been adopted.
According to the United States Bureau of Labor Statistics, 150,500 cases of RSI were reported in 1997. Eighty percent of these were in businesses such as manufacturing, assembly, and service jobs. The remainder of cases were reported in clerical, sales, professional managerial, secretarial, and data-entry jobs. Because of the nature of their work, musicians and dancers also have a high incidence of RSI, which has led to the creation of a new medical specialty, performing arts medicine.
Symptoms of RSI are varied, but they are roughly divided into three categories. Early signs include muscle aches and fatigue in the arms, wrists, or neck occurring during work, which may begin slowly over weeks or months, but which usually disappear with rest. After several months, aching and fatigue persist for longer periods and beyond the work day, diminishing the ability to perform everyday tasks. Advanced symptoms include aching and fatigue while at rest, problems sleeping due to pain, and partial or total disability. As symptoms become more severe, other complications may develop, such as depression resulting from chronic pain.
RSI INJURY
Injury from RSI primarily affects soft tissues, which include muscles, tendons, ligaments, nerves, and connective tissue. These injuries tend to increase in severity over time. Once the chain of injury has begun, RSI tends to progress unless the worker changes the factors that created the stress in the first place.
MUSCLE INJURY
Muscles of the forearm do most of the work of moving the fingers and wrists. These small muscle groups are not designed for extended periods of contraction, so they are vulnerable to injury during repetitive work. Injury is even more likely to occur if the stronger muscles of the back, shoulder, and upper arm are impaired because of poor posture or poorly fitted office equipment, forcing the forearm and hand muscles to do more work. With overuse, forearm muscles contract too often, decreasing the blood and oxygen supply to the muscle. Lactic acid and toher metabolic products build up in the muscle, causing fatigue and pain. The muscle contracts further in response to the pain.
° Tendon Injury
The decreased blood supply to the muscles in the arms causes the tendons to tighten, which in turn limits wrist and finger range of motion. When tendons are continually tightened because of muscle injury and contraction, they can be injured by friction as they rub against ligaments or bone, causing the inflammation and pain known as tendinitis. As tendons change their angle (as when bending or straightening the wrist), they are kept in place by a variety of sheaths and pulleys similar to the guide rings on a fishing rod. Friction in these areas can cause inflammation and swelling of the sheath and tendon known as tenosynovitis. When this occurs at the base of the thumb, it is called deQervain's disease.
° Nerve Injury
Nerves can be squeezed or compressed when surrounding tissues swell. A diminished blood supply can also damage nerve tissue. Friction, or rubbing against inflamed muscle or tendons, injures nerves. Nerves in the spine can be compressed by ruptured discs causing a condition called spondylosis. This tends to occur more frequently in the neck and lower back. Nerve root pain caused by bone compression as the nerves exit the spinal column is called radiculopathy. As the nerves enter the arms, forearms, and wrists, they encounter a number of tight spots or tunnels where compression or traction (pulling) can occur, including the cubital tunnel (ulnar nerve), radial tunnel (radial nerve), and carpal tunnel (median nerve). Carpal tunnel syndrome, a commonly diagnosed form of RSI, develops when the nerves of the wrist become compressed by inflamed tendons. Symptoms include tingling and numbness in the wrist and hand.
PREVENTION AND TREATMENT
Preventing RSI relies primarily on changes in work style, pacing, conditioning, and training. Sustained keyboard and production line work can lead to a round-shouldered posture with the neck thrust forward. This posture can damage nerves and weakens the shoulder and upper back muscles. Eventually the burden of work shifts to weaker muscles of the forearms and hands. For computer users this is often compounded by wrist rests that encourage excessive forearm and hand muscle use and awkward wrist positions that can result in muscle, tendon, and nerve damage. Poorly designed tools can also cause similar problems.
To minimize these potential strains and injuries, it is necessary to improve the ergonomics of the work environment. Ergonomics is the study and practice of arranging furniture and equipment to make work comfortable. For example, computer users benefit from basic ergonomic rules for proper positioning at the keyboard. An adjustable chair is essential, feet should be planted firmly on the ground, and the arms should be free to move without obstruction from arm rests. Production line equipment should accommodate the height of the workers so that they can maintain a healthy posture.
While the proper position of equipment is important, how the hands and upper body are used is also critical. Basic computer typing technique that teaches proper hand and arm placement is a critical preventive measure. Production line workers should be taught proper methods of lifting and bending. Pacing work by taking regular breaks, and physical conditioning are also important. Most workers who use their hands are essentially upper body athletes. Like any athlete, they must be in good physical condition to be able to perform their jobs safely.
Most forms of RSI involve soft tissue injuries that, with a few exceptions, can be treated conservatively. A medical exam followed by physical or occupational therapy, psychological counseling, and changes in the work situation are the critical components of treatment. A regular program of stretching, strengthening, postural training, and isometric and aerobic exercises done at home and at work is essential. Chronic pain may need the intervention of pain-management specialists who use a variety of techniques, including drug therapy, to lessen pain. Surgery is generally considered as a last resort for most RSI injuries.
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