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With Modernization Come Repetitive Movement Injuries

October 23, 2000|JONATHAN FIELDIN and VALERIE ULENE

While modern technology has reduced the physical demands of many workplaces, it has created a new set of more subtle physical demands--demands caused by repetitive movements.

The automation of manual processes, for example, has created assembly-line positions that require workers to perform the same manipulation over and over again; the advent of the computer has created data entry and clerical positions that require workers to type for hours on end. Although the demands may be subtle, they are not harmless. Work involving repetitive movements is causing an unfortunate number of injuries.

According to the Bureau of Labor Statistics, disorders associated with repetitive use account for about 60% of all occupational illnesses. Among the most common repetitive use injuries are carpal tunnel syndrome, tendinitis of the wrist, elbow and shoulder, and musculoskeletal problems affecting the neck and back.

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Of all of these conditions, carpal tunnel is the most common (or at least the most commonly reported). Carpal tunnel syndrome develops because a nerve that serves part of the hand gets squeezed as it passes through a narrow opening in the wrist called the carpal tunnel. The nerve is responsible for providing sensation to the index and middle finger and controlling muscles in the thumb. Pressure on the nerve can cause a set of classic symptoms that include numbness, tingling and pain in the index and middle fingers, and weakness of the thumb.

Tendons that travel through the carpal tunnel next to the nerve are one source of pressure. Although the canal is normally large enough to accommodate both the tendons and the nerve, any inflammation of the tendons can cause crowding of the nerve and may trigger symptoms.

Researchers have identified a number of nonoccupational factors that increase the likelihood of carpal tunnel syndrome. Medical conditions such as diabetes, hypothyroidism, congestive heart failure, kidney disease and arthritis can contribute to its development. Pregnancy, obesity and alcoholism can also increase the risk of this condition. Work factors, however, appear to be one of the most important factors. Studies have found a clear relationship between work requiring repetitive finger, hand or wrist movements (such as work on a computer keyboard) and carpal tunnel syndrome. Jobs that expose the hands and wrists to substantial vibration (work involving power tools, for example) also significantly increase the risk of this disorder.

Carpal tunnel syndrome can often be diagnosed based upon a thorough medical history and physical examination. If carpal tunnel syndrome is suspected, nerve conduction studies that measure the speed at which impulses are transmitted down the nerve may be performed to confirm the diagnosis (in carpal tunnel syndrome, nerve conduction is abnormally slow).

Initially, carpal tunnel syndrome is typically treated with splints that prevent the wrist from bending and twisting, and anti-inflammatory medications, such as ibuprofen, to decrease tissue inflammation in and around the canal. In some cases, steroids are injected directly into the canal in order to bring down inflammation and swelling. Surgery may be necessary in very severe cases or if symptoms are not relieved with more conservative measures. Surgery involves opening up the canal, thereby relieving pressure on the nerve.

Tendons throughout the hand, wrist, elbow and shoulder are susceptible to the damaging effects of repetitive movements. Like the tendons involved in carpal tunnel syndrome, they can become inflamed and painful when overused. Jobs requiring repetitive, forceful bending of the elbow, for example, can cause lateral epicondylitis, or "tennis elbow"; jobs involving repetitive movements of the fingers can result in "trigger finger." When recognized early, these conditions usually respond to a course of anti-inflammatory medications and rest. Steroid injections are sometimes necessary, however, to help reduce inflammation.

Unfortunately, it is impossible to know how an individual will respond to repetitious work and who will develop overuse injuries. Some people tolerate this type of work extremely well and can perform extremely repetitious tasks without injury. Others, however, have a much lower tolerance for it and are easily injured.

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